1.
Monosodium glutamate
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Monosodium glutamate is the sodium salt of glutamic acid, one of the most abundant naturally occurring non-essential amino acids. Monosodium glutamate is found naturally in tomatoes, cheese and other foods and it was first prepared in 1908 by Japanese biochemist Kikunae Ikeda, who was trying to isolate and duplicate the savory taste of kombu, an edible seaweed used as a base for many Japanese soups. MSG as a flavor enhancer balances, blends, and rounds the perception of other tastes, the U. S. Food and Drug Administration has given MSG its generally recognized as safe designation. The European Union classifies it as a food additive permitted in certain foods, MSG has the HS code 29224220 and the E number E621. Pure MSG is reported not to have a pleasant taste until it is combined with a savory aroma, the basic sensory function of MSG is attributed to its ability to enhance savory taste-active compounds when added in the proper concentration. The optimum concentration varies by food, in soup, the pleasure score rapidly falls with the addition of more than one gram of MSG per 100 mL. The sodium content of MSG, 12%, is about one-third of that in sodium chloride, although other salts of glutamate have been used in low-salt soups, they are less palatable than MSG. A popular belief is that MSG can cause headaches and other feelings of discomfort, MSG has been used for more than 100 years to season food, with a number of studies conducted on its safety. Consumption and manufacture of high-salt and high-glutamate foods, which contain sodium and glutamate, stretch back far longer, with evidence of cheese manufacture as early as 5,500 BC. International and national bodies governing food additives currently consider MSG safe for consumption as a flavor enhancer. Under normal conditions, humans can metabolize relatively large quantities of glutamate, the median lethal dose is between 15 and 18 g/kg body weight in rats and mice, respectively, five times greater than the LD50 of salt. The use of MSG as an additive and the natural level of glutamic acid in foods are not toxicological concerns in humans. According to the report, no support the role of glutamate in chronic disease. A controlled, double-blind, multiple-location clinical trial failed to demonstrate a relationship between the MSG symptom complex and actual MSG consumption, no statistical association has been demonstrated, and the few responses were inconsistent. No symptoms were observed when MSG was administered with food, adequately controlling for experimental bias includes a double-blind, placebo-controlled experimental design and administration by capsule, because of the unique aftertaste of glutamates. In a study by Tarasoff and Kelly,71 fasting participants were given 5 g of MSG, a study by Geha et al. tested the reaction of 130 subjects with a reported sensitivity to MSG. Multiple DBPC trials were performed, with subjects exhibiting at least two symptoms continuing, two people out of the 130 responded to all four challenges. Because of the low prevalence, the researchers concluded that a response to MSG was not reproducible, studies exploring MSGs role in obesity have yielded mixed results
2.
European Union
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The European Union is a political and economic union of 28 member states that are located primarily in Europe. It has an area of 4,475,757 km2, the EU has developed an internal single market through a standardised system of laws that apply in all member states. Within the Schengen Area, passport controls have been abolished, a monetary union was established in 1999 and came into full force in 2002, and is composed of 19 EU member states which use the euro currency. The EU operates through a system of supranational and intergovernmental decision-making. The EU traces its origins from the European Coal and Steel Community, the community and its successors have grown in size by the accession of new member states and in power by the addition of policy areas to its remit. While no member state has left the EU or its antecedent organisations, the Maastricht Treaty established the European Union in 1993 and introduced European citizenship. The latest major amendment to the basis of the EU. The EU as a whole is the largest economy in the world, additionally,27 out of 28 EU countries have a very high Human Development Index, according to the United Nations Development Programme. In 2012, the EU was awarded the Nobel Peace Prize, through the Common Foreign and Security Policy, the EU has developed a role in external relations and defence. The union maintains permanent diplomatic missions throughout the world and represents itself at the United Nations, the World Trade Organization, the G7, because of its global influence, the European Union has been described as an emerging superpower. After World War II, European integration was seen as an antidote to the nationalism which had devastated the continent. 1952 saw the creation of the European Coal and Steel Community, the supporters of the Community included Alcide De Gasperi, Jean Monnet, Robert Schuman, and Paul-Henri Spaak. These men and others are credited as the Founding fathers of the European Union. In 1957, Belgium, France, Italy, Luxembourg, the Netherlands and West Germany signed the Treaty of Rome and they also signed another pact creating the European Atomic Energy Community for co-operation in developing nuclear energy. Both treaties came into force in 1958, the EEC and Euratom were created separately from the ECSC, although they shared the same courts and the Common Assembly. The EEC was headed by Walter Hallstein and Euratom was headed by Louis Armand, Euratom was to integrate sectors in nuclear energy while the EEC would develop a customs union among members. During the 1960s, tensions began to show, with France seeking to limit supranational power, Jean Rey presided over the first merged Commission. In 1973, the Communities enlarged to include Denmark, Ireland, Norway had negotiated to join at the same time, but Norwegian voters rejected membership in a referendum
3.
European Free Trade Association
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The European Free Trade Association is a regional trade organisation and Free trade area consisting of four European states, Iceland, Liechtenstein, Norway, and Switzerland. The organisation operates in parallel with the European Union, and all the four member states participate in the EUs single market, the Stockholm Convention, to establish the EFTA, was signed on 4 January 1960 in the Swedish capital by seven countries. On 3 May 1960, the EFTA was established serving as a trade bloc for the European states who were unable or unwilling to join the then European Economic Community. Today, only two founding members remain, Norway and Switzerland, the other five of which were Austria, Denmark, Portugal, Sweden and the United Kingdom. While the EFTA is not a union and member states have full rights to enter into bilateral third-country trade arrangements. As a result, its states have jointly concluded Free trade agreements with a number of other countries. Switzerland has a set of agreements with the EU instead. On 12 January 1960, the Treaty on the European Free Trade Association was initiated in the Golden Hall of the Princes Palace of Stockholm and this established the progressive elimination of customs duties on industrial products, but did not affect agricultural products or maritime trade. This was rather less than the increase enjoyed by countries inside the EEC, after the accession of Denmark, Ireland, and the UK to the EEC in January 1973, the EFTA began to falter. For this reason, most countries eased or eliminated their trade tariffs in preparation to join the EEC, then, four members remained, Switzerland, Norway, Liechtenstein and Iceland. The interactive Free Trade Map gives an overview of the partners worldwide, the Portugal Fund was established in 1975 when Portugal was still a member of EFTA. It was to provide funding for the development of Portugal after the Carnation Revolution and this followed the period of economic sanctions by most of the international community, having left Portugal economically underdeveloped compared to the rest of the western Europe. When Portugal left EFTA in 1985 in order join the EEC, the Fund originally took the form of a low-interest loan from the EFTA member states to Portugal, to the value of $US100 million. Repayment was originally to commence in 1988, however EFTA then decided to postpone the start of repayments until 1998, the Portugal Fund has now been dissolved by the member states of EFTA. The founding members of the EFTA were Austria, Denmark, Norway, Portugal, Sweden, Switzerland, during the 1960s, these countries were often referred to as the Outer Seven, as opposed to the Inner Six of the then European Economic Community. Finland became a member in 1961 and a full member in 1986. The United Kingdom and Denmark joined the EEC in 1973, Portugal also left EFTA for the European Community in 1986. Liechtenstein joined the EFTA in 1991, Austria, Sweden, and Finland joined the EU in 1995 and thus ceased to be EFTA members
4.
Nutrition facts label
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The nutrition facts label is a label required on most packaged food in many countries. Most countries also release overall nutrition guides for general educational purposes, in some cases, the guides are based on different dietary targets for various nutrients than the labels on specific foods. Australia and New Zealand use an information panel of the following format, Other items are included as appropriate. In April 2013 the New Zealand government introduced rules around common claims made on food packaging, in Canada, a standardized Nutrition Facts label was introduced as part of regulations passed in 2003, and became mandatory for most prepackaged food products on December 12,2005. In accordance with food packaging laws in the country, all information, including the nutrition label, canadian regulation tightly controls the manner in which the nutrition fact table data are laid out. There is a variety of possible formats for use on a given food package. A selection hierarchy is used to select among the many formats and this results in standard formats being considered for use before horizontal and linear formats. The selection hierarchy also allows the NFT to occupy no more than 15% of the packages available display area. In practice, determining the ADS of a package, and selecting the appropriate NFT format, a new regulation is now in force. Nutritional labelling becomes mandatory for most pre-packaged foods as from December 2016, in the European Union, along the old rules, the information is most often labelled Nutrition Information. An example is shown on the right, the panel is optional, but if provided, the prescribed content and format must be followed. It will always give values for a set quantity —100 g or 100 ml of the product — and often also for a defined serving, first will come the energy values, in both kilocalories and kilojoules. Then will come a breakdown of constituent elements, usually most or all of protein, carbohydrate, starch, sugar, fat, fibre and sodium. The fat figure is likely to be broken down into saturated and unsaturated fat. With regards to health claims and nutrition claims, these are harmonised in the EU through Regulation 1924/2006, in November 2012, the European Commission published two new regulations, Regulation No. Certain nutrition claim groups as of Regulation No 1924/2006 had to be changed, moreover, the health claims associated to barley beta-gluten were amended. Within Regulation 1924, there are definitions of terms such as low fat, high fibre. All health claims have been harmonised in the European Union and they can be used if they have been approved by EFSA
5.
European Food Safety Authority
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The European Food Safety Authority is the agency of the European Union that provides independent scientific advice and communicates on existing and emerging risks associated with the food chain. EFSA was established in February 2002, is based in Parma, Italy, the work of EFSA covers all matters with a direct or indirect impact on food and feed safety, including animal health and welfare, plant protection and plant health and nutrition. EFSA also communicates to the public in an open and transparent way on all matters within its remit and they are appointed by the Management Board. The Advisory Forum advises the Executive Director, in particular in drafting a proposal for the EFSAs work programmes and it is composed of representatives of national bodies responsible for risk assessment in the Member States, with observers from Norway, Iceland, Switzerland and the European Commission. The Scientific Committee and its Scientific Panels provide scientific opinions and advice, each within their own sphere of competence, the number and names of the Scientific Panels are adapted in the light of technical and scientific development by the European Commission at EFSAs request. The independent scientific experts are appointed by the Management Board upon a proposal from the Executive Director for three-year terms, the scientific output of the European Food Safety Authority is published in the EFSA Journal, an open-access, online scientific journal. This concerns risk assessment in relation to food and feed and includes nutrition, animal health and welfare, plant health, EFSA has been criticised for their alleged overregulation, as well as allegations of frequent conflicts of interest. EFSA has also criticised by the NGO CHEM Trust for misrepresenting the results of their expert committees report on Bisphenol A in January 2015. EFSA claimed in the abstract, press release and briefing that Bisphenol A posed no risk to health, EFSA later modified the abstract to correct this error, though the press release remains unchanged. EFSA have argued that use of no concern in their press release and Bisphenol A briefing is to ensure these materials are accessible
6.
Food coloring
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Food coloring, or color additive, is any dye, pigment or substance that imparts color when it is added to food or drink. They come in many forms consisting of liquids, powders, gels, Food coloring is used both in commercial food production and in domestic cooking. Food colorants are used in a variety of non-food applications including cosmetics, pharmaceuticals, home craft projects. People associate certain colors with certain flavors, and the color of food can influence the flavor in anything from candy to wine. During the Middle Ages, the economy in the European countries was based on agriculture, under feudalism, aesthetic aspects were not considered, at least not by the vast majority of the generally very poor population. This situation changed with urbanization at the beginning of the Modern Age, one of the very first food laws, created in Augsburg, Germany, in 1531, concerned spices or colorants and required saffron counterfeiters to be burned. With the onset of the revolution, people became dependent on foods produced by others. These new urban dwellers demanded food at low cost, analytical chemistry was still primitive and regulations few. Copper arsenite was used to recolor used tea leaves for resale and it also caused two deaths when used to color a dessert in 1860. Again his tea if mixed or green, he would not escape without the administration of a little Prussian blue. Many color additives had never tested for toxicity or other adverse effects. Historical records show that injuries, even deaths, resulted from tainted colorants, in 1851, about 200 people were poisoned in England,17 of them fatally, directly as a result of eating adulterated lozenges. Originally, these were dubbed coal-tar colors because the materials were obtained from bituminous coal. Many synthesized dyes were easier and less costly to produce and were superior in coloring properties when compared to naturally derived alternatives, some synthetic food colorants are diazo dyes. Diazo dyes are prepared by coupling of a compound with a second aromatic hydrocarbons. The resulting compounds contain conjugated systems that absorb light in the visible parts of the spectrum. The attractiveness of the synthetic dyes is that their color, lipophilicity, the color of the dyes can be controlled by selecting the number of azo-groups and various substituents. Yellow shades are often achieved by using acetoacetanilide, Red colors are often azo compounds
7.
Codex Alimentarius
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The Codex Alimentarius is a collection of internationally recognized standards, codes of practice, guidelines, and other recommendations relating to foods, food production, and food safety. Its name is derived from the Codex Alimentarius Austriacus, the Commissions main goals are to protect the health of consumers and ensure fair practices in the international food trade. The Codex Alimentarius is recognized by the World Trade Organization as a reference point for the resolution of disputes concerning food safety. As of 2012, there were 186 members of the Codex Alimentarius Commission,186 member countries and one member organization, there were 215 Codex observers,49 intergovernmental organizations,150 non-governmental organizations, and 16 United Nations organizations. The Codex Alimentarius covers all foods, whether processed, semi-processed or raw and it also contains guidelines for the management of official i. e. governmental import and export inspection and certification systems for foods. The Codex Alimentarius is published in the six languages of the United Nations, Arabic, Chinese, English, French, Spanish. Not all texts are available in all languages, the proposal was agreed, but protests halted its implementation. The 28th Session of the Codex Alimentarius Commission was subsequently held July 4–9,2005. be encouraged to select a balanced diet from food before considering any vitamin and mineral supplement. In cases where the intake from the diet is insufficient or where consumers consider their diet requires supplementation, vitamin and this text has been the subject of considerable controversy among proponents of dietary supplements. Many countries regulate such substances as therapeutic goods or pharmaceuticals or by some other category, the United Nations Food and Agriculture Organization and World Health Organization will implement these criteria with labelling to stop consumers overdosing on vitamin and mineral food supplements. The Codex Alimentarius Commission has said that the Guidelines call for labelling that contains information on maximum consumption levels of vitamin, the WHO has also said that the Guidelines ensure that consumers receive beneficial health effects from vitamins and minerals. In 2004, similarities were noted between the EUs Food Supplements Directive and the Codex Alimentarius draft guidelines for vitamin and mineral supplements, published 13 July 2012 by the Food Inspection & Safety Service of the U. S. D. A
8.
Gulf Cooperation Council
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Its member states are Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates. The Charter of the Gulf Cooperation Council was signed on 25 May 1981, all current member states are monarchies, including three constitutional monarchies, two absolute monarchies, and one federal monarchy. There have been regarding the future membership of Jordan, Morocco. Objections have been raised against the proposal by other countries, in 2014, Bahrain prime minister Khalifa bin Salman Al Khalifa said that current events in the region highlighted the importance of the proposal. In order to reduce their dependence on oil in the future, the original union comprised the 1,032, 093-square-mile Persian Gulf states of Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates. The unified economic agreement between the countries of the Gulf Cooperation Council was signed on 11 November 1981 in Abu Dhabi and these countries are often referred to as the GCC states. Following the announcement that the bank for the monetary union would be located in Riyadh and not in the UAE. The name Khaleeji has been proposed as a name for this currency, if realised, the GCC monetary union would be the second largest supranational monetary union in the world, measured by GDP of the common-currency area. In an effort to build a tax base and economic foundation before the run out. Other regional funds also have hundreds of billions of dollars of assets under management. The region is also a hotspot for events, including the 2006 Asian Games in Doha. Doha also submitted an application for the 2016 Summer Olympic Games. Qatar was later chosen to host the 2022 FIFA World Cup, the logo of the GCC consists of two concentric circles. On the upper part of the circle, the Bismillah phrase is written in Arabic. The inner circle contains a hexagonal shape that represents the Councils six member countries. The inside of the hexagon is filled by a map encompassing the Arabian Peninsula, on which the areas of the countries are borderless. On the edge of the hexagon are colors representing the flags of the six member countries, a common market was launched on 1 January 2008 with plans to realise a fully integrated single market. It eased the movement of goods and services, however, implementation lagged behind after the 2009 financial crisis
9.
Israel
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Israel, officially the State of Israel, is a country in the Middle East, on the southeastern shore of the Mediterranean Sea and the northern shore of the Red Sea. The country contains geographically diverse features within its small area. Israels economy and technology center is Tel Aviv, while its seat of government and proclaimed capital is Jerusalem, in 1947, the United Nations adopted a Partition Plan for Mandatory Palestine recommending the creation of independent Arab and Jewish states and an internationalized Jerusalem. The plan was accepted by the Jewish Agency for Palestine, next year, the Jewish Agency declared the establishment of a Jewish state in Eretz Israel, to be known as the State of Israel. Israel has since fought several wars with neighboring Arab states, in the course of which it has occupied territories including the West Bank, Golan Heights and it extended its laws to the Golan Heights and East Jerusalem, but not the West Bank. Israels occupation of the Palestinian territories is the worlds longest military occupation in modern times, efforts to resolve the Israeli–Palestinian conflict have not resulted in peace. However, peace treaties between Israel and both Egypt and Jordan have successfully been signed, the population of Israel, as defined by the Israel Central Bureau of Statistics, was estimated in 2017 to be 8,671,100 people. It is the worlds only Jewish-majority state, with 74. 8% being designated as Jewish, the countrys second largest group of citizens are Arabs, at 20. 8%. The great majority of Israeli Arabs are Sunni Muslims, including significant numbers of semi-settled Negev Bedouins, other minorities include Arameans, Armenians, Assyrians, Black Hebrew Israelites, Circassians, Maronites and Samaritans. Israel also hosts a significant population of foreign workers and asylum seekers from Africa and Asia, including illegal migrants from Sudan, Eritrea. In its Basic Laws, Israel defines itself as a Jewish, Israel is a representative democracy with a parliamentary system, proportional representation and universal suffrage. The prime minister is head of government and the Knesset is the legislature, Israel is a developed country and an OECD member, with the 35th-largest economy in the world by nominal gross domestic product as of 2016. The country benefits from a skilled workforce and is among the most educated countries in the world with one of the highest percentage of its citizens holding a tertiary education degree. The country has the highest standard of living in the Middle East and the third highest in Asia, in the early weeks of independence, the government chose the term Israeli to denote a citizen of Israel, with the formal announcement made by Minister of Foreign Affairs Moshe Sharett. The names Land of Israel and Children of Israel have historically used to refer to the biblical Kingdom of Israel. The name Israel in these phrases refers to the patriarch Jacob who, jacobs twelve sons became the ancestors of the Israelites, also known as the Twelve Tribes of Israel or Children of Israel. The earliest known artifact to mention the word Israel as a collective is the Merneptah Stele of ancient Egypt. The area is known as the Holy Land, being holy for all Abrahamic religions including Judaism, Christianity, Islam
10.
Vitamin C
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Vitamin C, also known as ascorbic acid and L-ascorbic acid, is a vitamin found in food and used as a dietary supplement. As a supplement it is used to treat and prevent scurvy, evidence does not support use in the general population for the prevention of the common cold. It may be taken by mouth or by injection, large doses may cause gastrointestinal discomfort, headache, trouble sleeping, and flushing of the skin. Normal doses are safe during pregnancy, Vitamin C is an essential nutrient involved in the repair of tissue. Foods that contain vitamin C include citrus fruit, tomatoes, Vitamin C was discovered in 1912, isolated in 1928, and first made in 1933. It is on the World Health Organizations List of Essential Medicines, Vitamin C is available as a generic medication and over the counter. In 2015, the wholesale cost in the world was about 0.003 to 0.007 USD per tablet. In some countries, ascorbic acid may be added to such as breakfast cereal. A2012 Cochrane review found no effect of vitamin C supplementation on overall mortality, although rare in modern times, scurvy and its associated destabilization of collagen, connective tissue, and bone can be prevented by adequate vitamin C intake. A2014 review found that, Currently, the use of high-dose IV vitamin C cannot be recommended outside of a clinical trial, a 2013 Cochrane review found no evidence that vitamin C supplementation reduces the risk of lung cancer in healthy or high risk people. A2014 meta-analysis found that vitamin C intake might protect against lung cancer risk, a second meta-analysis found no effect on the risk of prostate cancer. Two meta-analyses evaluated the effect of vitamin C supplementation on the risk of colorectal cancer, one found a weak association between vitamin C consumption and reduced risk, and the other found no effect of supplementation. A2013 meta-analysis found no evidence that vitamin C supplementation reduces the risk of myocardial infarction, stroke, cardiovascular mortality, however, a second analysis found an inverse relationship between circulating vitamin C levels or dietary vitamin C and the risk of stroke. A meta-analysis of 44 clinical trials has shown a significant positive effect of vitamin C on endothelial function when taken at doses greater than 500 mg per day. The researchers noted that the effect of vitamin C supplementation appeared to be dependent on health status, a 2010 review found no role for vitamin C supplementation in the treatment of rheumatoid arthritis. Studies examining the effects of vitamin C intake on the risk of Alzheimers disease have reached conflicting conclusions, maintaining a healthy dietary intake is probably more important than supplementation for achieving any potential benefit. Vitamin C supplementation above the RDA has been used in trials to study a potential effect on preventing and slowing the progression of age-related cataract, however, no significant effects were found from the research. Vitamin Cs effect on the cold has been extensively researched
11.
Lycopene
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Although lycopene is chemically a carotene, it has no vitamin A activity. Foods that are not red may also contain lycopene, such as asparagus, like all carotenoids, lycopene is a polyunsaturated hydrocarbon, i. e. an unsubstituted alkene. Structurally, lycopene is a tetraterpene and assembled from eight isoprene units that are composed entirely of carbon, lycopenes eleven conjugated double bonds give its deep red color and its antioxidant activity. Owing to the color, lycopene is a useful food coloring and is approved for usage in the USA, Australia and New Zealand. Lycopene is not a nutrient for humans, but is commonly found in the diet mainly from dishes prepared from tomatoes. Lycopene is a symmetrical tetraterpene assembled from eight isoprene units and it is a member of the carotenoid family of compounds, and because it consists entirely of carbon and hydrogen, is also a carotene. Isolation procedures for lycopene were first reported in 1910, and the structure of the molecule was determined by 1931, in its natural, all-trans form, the molecule is long and straight, constrained by its system of eleven conjugated double bonds. Lycopene absorbs all but the longest wavelengths of light, so it appears red. Plants and photosynthetic bacteria naturally produce all-trans lycopene, but a total of 72 geometric isomers of the molecule are sterically possible, when exposed to light or heat, lycopene can undergo isomerization to any of a number of these cis-isomers, which have a bent rather than linear shape. Different isomers were shown to have different stabilities due to their molecular energy, in the human bloodstream, various cis-isomers constitute more than 60% of the total lycopene concentration, but the biological effects of individual isomers have not been investigated. Lycopene, the pigment in tomato-containing sauces, turns plastic cookware orange and is insoluble in water and it can be dissolved only in organic solvents and oils. Because of its non-polarity, lycopene in food preparations will stain any sufficiently porous material, to remove this staining, the plastics can be soaked in a solution containing a small amount of household bleach. Carotenoids like lycopene are important pigments found in photosynthetic pigment-protein complexes in plants, photosynthetic bacteria, fungi and they are responsible for the bright colors of fruits and vegetables, perform various functions in photosynthesis, and protect photosynthetic organisms from excessive light damage. Lycopene is a key intermediate in the biosynthesis of many important carotenoids, such as beta-carotene, the unconditioned biosynthesis of lycopene in eukaryotic plants and in prokaryotic cyanobacteria is similar, as are the enzymes involved. Synthesis begins with mevalonic acid, which is converted into dimethylallyl pyrophosphate and this is then condensed with three molecules of isopentenyl pyrophosphate, to give the twenty-carbon geranylgeranyl pyrophosphate. Two molecules of this product are then condensed in a configuration to give the forty-carbon phytoene. Through several desaturation steps, phytoene is converted into lycopene, the two terminal isoprene groups of lycopene can be cyclized to produce beta-carotene, which can then be transformed into a wide variety of xanthophylls. Fruits and vegetables that are high in lycopene include autumn olive, gac, tomatoes, watermelon, pink grapefruit, pink guava, papaya, seabuckthorn, wolfberry, the lycopene content of tomatoes depends on species and increases as the fruit ripens
12.
Carrot
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The carrot is a root vegetable, usually orange in colour, though purple, black, red, white, and yellow cultivars exist. Carrots are a form of the wild carrot, Daucus carota, native to Europe. The plant probably originated in Persia and originally cultivated for its leaves, the most commonly eaten part of the plant is the taproot, although the greens are sometimes eaten as well. The domestic carrot has been bred for its greatly enlarged, more palatable. The carrot is a plant in the umbellifer family Apiaceae. At first, it grows a rosette of leaves while building up the enlarged taproot, fast-growing cultivars mature within three months of sowing the seed, while slower-maturing cultivars are harvested four months later. The United Nations Food and Agriculture Organization reports that production of carrots and turnips for the calendar year 2013 was 37.2 million tonnes. Carrots are widely used in many cuisines, especially in the preparation of salads, in Old English, carrots were not clearly distinguished from parsnips, the two were collectively called moru or more. Various languages still use the word for carrot as they do for root. Molecular and genetic studies, along with history, support the idea that the cultivated/domesticated carrot has a single origin in Central Asia. The wild ancestors of the carrot are likely to have originated in Persia, which remains the centre of diversity for Daucus carota, when they were first cultivated, carrots were grown for their aromatic leaves and seeds rather than their roots. Carrot seeds have been found in Switzerland and Southern Germany dating back to 2000–3000 BC, some close relatives of the carrot are still grown for their leaves and seeds, for example, parsley, cilantro/coriander, fennel, dill and cumin. Three different types of carrots are depicted, and the states of them that the root can be cooked. The plant appears to have been introduced into Spain by the Moors in the 8th century, in the 10th century, in worldwide locations like West Asia, India and Europe, the roots were purple. The modern carrot originated in Afghanistan at about this time, the Jewish scholar Simeon Seth describes both red and yellow carrots in the 11th century. The 12th-century Arab-Andalusian agriculturist, Ibn al-Awwam, also mentions roots of these colours, cultivated carrots appeared in China in the 14th century, and in Japan in the 18th century. Orange-coloured carrots appeared in the Netherlands in the 17th century, which has been related to the fact that the Dutch flag at the time, the Princes Flag, included orange. These, the carrots, were intended by the English antiquary John Aubrey when he noted in his memoranda
13.
Preservative
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In general, preservation is implemented in two modes, chemical and physical. Chemical preservation entails adding chemical compounds to the product, physical preservation entails processes such as refrigeration or drying. Preservative food additives reduce the risk of infections, decrease microbial spoilage. Some physical techniques for preservation include dehydration, UV-C radiation, freeze-drying. Chemical preservation and physical preservation techniques are sometimes combined, antimicrobial preservatives prevent degradation by bacteria. This method is the most traditional and ancient type of preserving—ancient methods such as pickling and adding honey prevent microorganism growth by modifying the pH level, the most commonly used antimicrobial preservative is lactic acid. Common antimicrobial preservatives are presented in the table, nitrates and nitrites are also antimicrobial. The detailed mechanism of chemical compounds range from inhibiting growth of the bacteria to the inhibition of specific enzymes. The oxidation process spoils most food, especially those with a fat content. Fats quickly turn rancid when exposed to oxygen, antioxidants prevent or inhibit the oxidation process. The most common antioxidant additives are ascorbic acid and ascorbates, thus, antioxidants are commonly added to oils, cheese, and chips. Other antioxidants include the phenol derivatives BHA, BHT, TBHQ and these agents suppress the formation of hydroperoxides. Other preservatives include ethanol and methylchloroisothiazolinone, a variety of agents are added to sequester metal ions that otherwise catalyze the oxidation of fats. Common sequestering agents are disodium EDTA, citric acid, tartaric acid, citric and ascorbic acids target enzymes that degrade fruits and vegetables, e. g. phenolase which turns surfaces of cut apples and potatoes brown. Ascorbic acid and tocopherol, which are vitamins, are common preservatives, smoking entails exposing food to a variety of phenols, which are antioxidants. Natural preservatives include rosemary extract, hops, salt, sugar, vinegar, alcohol, diatomaceous earth, traditional preservatives, such as sodium benzoate have raised health concerns in the past. Benzoate was shown in a study to cause hypersensitivity in some asthma sufferers and this has caused reexamination of natural preservatives which occur in vegetables. Preservatives have been used since prehistoric times, smoked meat for example has phenols and other chemicals that retard spoilage
14.
Sorbate
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Sorbic acid, or 2, 4-hexadienoic acid, is a natural organic compound used as a food preservative. It has the chemical formula C6H8O2 and it is a colourless solid that is slightly soluble in water and sublimes readily. It was first isolated from the berries of the rowan tree. The traditional route to sorbic acid involves condensation of malonic acid and it can also be prepared from isomeric hexadienoic acids, which are available via a nickel-catalyzed reaction of allyl chloride, acetylene, and carbon monoxide. The route used commercially, however, is from crotonaldehyde and ketene, an estimated 30,000 tons are produced annually. Sorbic acid was isolated in 1859 by distillation of oil by A. W. von Hofmann. This affords the lactone of sorbic acid, which he converted to sorbic acid by hydrolysis and its antimicrobial activities were discovered in the late 1930s and 1940s, and it became commercially available in the late 1940s and 1950s. Beginning in the 1980s, sorbic acid and its salts were used as inhibitors of Clostridium botulinum in meat products to replace the use of nitrites, with a pKa of 4.76, it is about as acidic as acetic acid. In general the salts are preferred over the form because they are more soluble in water. The optimal pH for the activity is below pH6.5. Sorbates are generally used at concentrations of 0. 025% to 0. 10%, adding sorbate salts to food will, however, raise the pH of the food slightly so the pH may need to be adjusted to assure safety. It is found in other foods, such as cheeses. The pentadiene manifests as an odor of kerosene or petroleum. Other detoxification reactions include reduction to 4-hexenol and 4-hexenoic acid, Sorbic acid can also be used as an additive for cold rubber, and as an intermediate in the manufacture of some plasticizers and lubricants. The LD50 value of sorbic acid is estimated to be between 7.4 and 10 g/kg, which is quite high, the compound is relatively unstable and is rapidly degraded in soil, hence it is often considered environmentally friendly. Sorbitol Polysorbate Acids in wine Sorbic inchem. org
15.
Sulfite
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Sulfites or sulphites are compounds that contain the sulfite ion, SO2−3. The sulfite ion is the base of bisulfite. Although its acid is elusive, its salts are widely used, Sulfites are substances that naturally occur in some foods and the human body. They are also used as regulated food additives, the structure of the sulfite anion can be described with three equivalent resonance structures. There is also a lone pair on the sulfur, so the structure predicted by VSEPR theory is trigonal pyramidal. In the hybrid resonance structure, the S-O bonds are equivalently of bond order one, evidence from 17O NMR spectroscopic data suggests that protonation of the sulfite ion gives a mixture of isomers, Sulfites are used as a food preservative or enhancer. Sulfites are commonly introduced to arrest fermentation at a desired time, sulfur dioxide protects wine from not only oxidation, but also from bacteria. Without sulfites, grape juice would turn to vinegar. Organic wines are not necessarily sulfite-free, but generally have lower amounts, in general, white wines contain more sulfites than red wines and sweeter wines contain more sulfites than drier ones. In the United States, wines bottled after mid-1987 must have a label stating that they contain sulfites if they contain more than 10 parts per million, in the European Union an equivalent regulation came into force in November 2005. In 2012, a new regulation for organic wines came into force, Sulfites are often used as preservatives in dried fruits, preserved radish, and dried potato products. Most beers no longer contain sulfites, although some alcoholic ciders contain them, although shrimp are sometimes treated with sulfites on fishing vessels, the chemical may not appear on the label. In 1986, the Food and Drug Administration in the United States banned the addition of sulfites to all fresh fruit, E numbers for sulfites as food additives are, Sulfites are counted among the top nine food allergens, but a reaction to sulfite is not a true allergy. Some people have positive skin allergy tests to sulfites indicating true allergy and it may cause breathing difficulty within minutes after eating a food containing it. Asthmatics and possibly people with sensitivity are at an elevated risk for reaction to sulfites. Anaphylaxis and life-threatening reactions are rare, other potential symptoms include sneezing, swelling of the throat, hives, and migraine. In 1986, the U. S. Food and Drug Administration banned the use of sulfites as preservatives on foods intended to be eaten fresh and this has contributed to the increased use of erythorbic acid and its salts as preservatives. In the U. S. Sulfites used in food processing, the products most likely to contain sulfites do not require ingredients labels, so the presence of sulfites usually is undisclosed
16.
Phenol
–
Phenol, also known as carbolic acid, is an aromatic organic compound with the molecular formula C6H5OH. It is a crystalline solid that is volatile. The molecule consists of a phenyl group bonded to a hydroxyl group and it is mildly acidic and requires careful handling due to its propensity to cause chemical burns. Phenol was first extracted from tar, but today is produced on a large scale from petroleum. It is an important industrial commodity as a precursor to many materials and it is primarily used to synthesize plastics and related materials. Phenol and its derivatives are essential for production of polycarbonates, epoxies, Bakelite, nylon, detergents, herbicides such as phenoxy herbicides. Phenol is appreciably soluble in water, with about 84.2 g dissolving in 1000 mL, homogeneous mixtures of phenol and water at phenol to water mass ratios of ~2.6 and higher are possible. The sodium salt of phenol, sodium phenoxide, is far more water-soluble and it reacts completely with aqueous NaOH to lose H+, whereas most alcohols react only partially. One explanation for the increased acidity over alcohols is resonance stabilization of the anion by the aromatic ring. In this way, the charge on oxygen is delocalized on to the ortho. In another explanation, increased acidity is the result of orbital overlap between the lone pairs and the aromatic system. The pKa of the enol of acetone is 10.9, the acidities of phenol and acetone enol diverge in the gas phase owing to the effects of solvation. About 1⁄3 of the acidity of phenol is attributable to inductive effects. Phenolate esters are more stable toward hydrolysis than acid anhydrides and acyl halides but are sufficiently reactive under mild conditions to facilitate the formation of amide bonds, Phenol exhibits keto-enol tautomerism with its unstable keto tautomer cyclohexadienone, but only a tiny fraction of phenol exists as the keto form. The equilibrium constant for enolisation is approximately 10−13, meaning only one in every ten trillion molecules is in the keto form at any moment. The small amount of stabilisation gained by exchanging a C=C bond for a C=O bond is more than offset by the large destabilisation resulting from the loss of aromaticity, Phenol therefore exists essentially entirely in the enol form. Phenoxides are enolates stabilised by aromaticity, under normal circumstances, phenoxide is more reactive at the oxygen position, but the oxygen position is a hard nucleophile whereas the alpha-carbon positions tend to be soft. Phenol is highly reactive toward electrophilic aromatic substitution as the oxygen atoms pi electrons donate electron density into the ring, by this general approach, many groups can be appended to the ring, via halogenation, acylation, sulfonation, and other processes
17.
Formate
–
Formate is the anion derived from formic acid. Its formula is represented in various equivalent ways, CHOO− or HCOO− or HCO2− and it is the product of deprotonation of formic acid. It is the simplest carboxylate anion, a formate is a salt or ester of formic acid. Formate is produced in large amounts in the mitochondria of embryonic cells. Formate is reversibly oxidized by the enzyme formate dehydrogenase from Desulfovibrio gigas, many form spontaneously when alcohols dissolve in formic acid. Formate salts have the formula M, such salts are prone to decarboxylation
18.
Nitrate
–
Nitrate is a polyatomic ion with the molecular formula NO−3 and a molecular mass of 62.0049 g/mol. Nitrates also describe the functional group RONO2. These nitrate esters are a class of explosives. The anion is the base of nitric acid, consisting of one central nitrogen atom surrounded by three identically bonded oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a charge of −1. This arrangement is used as an example of resonance. Like the isoelectronic carbonate ion, the ion can be represented by resonance structures. A common example of a nitrate salt is potassium nitrate. A rich source of nitrate in the human body comes from diets rich in leafy green foods, such as spinach. NO3- is the active component within beetroot juice and other vegetables. Nitrite and water are converted in the body to nitric oxide, nitrate salts are found naturally on earth as large deposits, particularly of nitratine, a major source of sodium nitrate. Nitrates are found in man-made fertilizers, as a byproduct of lightning strikes in earths nitrogen-oxygen rich atmosphere, nitric acid is produced when nitrogen dioxide reacts with water vapor. Nitrates are mainly produced for use as fertilizers in agriculture because of their solubility and biodegradability. The main nitrate fertilizers are ammonium, sodium, potassium, several million kilograms are produced annually for this purpose. The second major application of nitrates is as oxidizing agents, most notably in explosives where the oxidation of carbon compounds liberates large volumes of gases. Sodium nitrate is used to air bubbles from molten glass. Mixtures of the salt are used to harden some metals. Explosives and table tennis balls are made from celluloid, although nitrites are the nitrogen compound chiefly used in meat curing, nitrates are used in certain specialty curing processes where a long release of nitrite from parent nitrate stores is needed
19.
Acetate
–
An acetate /ˈæsᵻteɪt/ is a salt formed by the combination of acetic acid with an alkaline, earthy, or metallic base. Acetate also describes the base or ion typically found in aqueous solution. The neutral molecules formed by the combination of the acetate ion, the simplest of these is hydrogen acetate with corresponding salts, esters, and the polyatomic anion CH3CO2−, or CH3COO−. Most of the approximately 5 billion kilograms of acid produced annually in industry is used in the production of acetates. In nature, acetate is the most common building block for biosynthesis, for example, the fatty acids are produced by connecting the two carbon atoms from acetate to a growing fatty acid. When part of a salt, the formula of the ion is written as CH3CO2−, C2H3O2−. Chemists abbreviate acetate as OAc− or, less commonly, AcO−, thus, HOAc is the abbreviation for acetic acid, NaOAc for sodium acetate, and EtOAc for ethyl acetate. The abbreviation Ac is also encountered in chemical formulas to indicate the acetate ion. This abbreviation is not to be confused with the symbol of actinium, for example, the formula for sodium acetate might be abbreviated as NaAc, rather than NaC2H3O2. Although its systematic name is ethanoate, the common acetate remains the preferred IUPAC name, the acetate anion, −, is one of the carboxylate family. It is the base of acetic acid. Above a pH of 5.5, acetic acid converts to acetate, CH3COOH ⇌ CH3COO− + H+ Many acetate salts are ionic, examples of acetate complexes include chromium acetate and basic zinc acetate. Commercially important acetate salts are aluminium acetate, used in dyeing, ammonium acetate, a precursor to acetamide, all three salts are colourless and highly soluble in water. Acetate esters have the general formula CH3CO2R, where R is an organyl group, the esters are the dominant forms of acetate in the marketplace. Unlike the acetate salts, acetate esters are often liquids, lipophilic and they are popular because they have inoffensive, often sweet odors, they are inexpensive, and they are usually of low toxicity. Almost half of acetic acid production is consumed in the production of acetate, precursor to polyvinyl alcohol. The second largest use of acid is consumed in the production of cellulose acetate. In fact, acetate is jargon for cellulose acetate, which is used in the production of fibres or diverse products, Cellulose acetate can be found in many household products
20.
Lactic acid
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Lactic acid is an organic compound with the formula CH3CHCO2H. In its solid state, it is white and water-soluble, in its liquid state, it is clear. It is produced naturally and synthetically. With a hydroxyl group adjacent to the group, lactic acid is classified as an alpha-hydroxy acid. In the form of its base called lactate, it plays a role in several biochemical processes. In solution, it can ionize a proton from the carboxyl group, compared to acetic acid, its pKa is 1 unit less, meaning lactic acid deprotonates ten times more easily than acetic acid does. This higher acidity is the consequence of the hydrogen bonding between the α-hydroxyl and the carboxylate group. Lactic acid is chiral, consisting of two optical isomers, one is known as L--lactic acid or -lactic acid and the other, its mirror image, is D--lactic acid or -lactic acid. A mixture of the two in equal amounts is called DL-lactic acid, or racemic lactic acid, DL-lactic acid is miscible with water and with ethanol above its melting point which is around 17 or 18 °C. D-lactic acid and L-lactic acid have a melting point. In animals, L-lactate is constantly produced from pyruvate via the enzyme lactate dehydrogenase in a process of fermentation during normal metabolism and exercise. The concentration of lactate is usually 1–2 mmol/L at rest. In industry, lactic acid fermentation is performed by lactic acid bacteria and these bacteria can also grow in the mouth, the acid they produce is responsible for the tooth decay known as caries. In medicine, lactate is one of the components of lactated Ringers solution. These intravenous fluids consist of sodium and potassium cations along with lactate and chloride anions in solution with distilled water and it is most commonly used for fluid resuscitation after blood loss due to trauma, surgery, or burns. Lactic acid was isolated for the first time by the Swedish chemist Carl Wilhelm Scheele in 1780 from sour milk, the name reflects the lact- combining form derived from the Latin word for milk. In 1808, Jöns Jacob Berzelius discovered that lactic acid also is produced in muscles during exertion and its structure was established by Johannes Wislicenus in 1873. In 1856, Louis Pasteur discovered Lactobacillus and its role in the making of lactic acid, lactic acid started to be produced commercially by the German pharmacy Boehringer Ingelheim in 1895
21.
Propionate
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The propionate or propanoate ion is C2H5COO−. A propionic or propanoic compound is a salt or ester of propionic acid. In these compounds, propionate is often written in shorthand, as CH3CH2CO2 or simply EtCO2, propionates should not be confused with propenoates, the ions/salts/esters of propenoic acid. Sodium propionate, NaC2H5CO2 Methyl propionate, Calcium propionate, Ca2 Potassium propionate, KC2H5CO2 Fluticasone propionate, C25H31F3O5S
22.
Antioxidant
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An antioxidant is a molecule that inhibits the oxidation of other molecules. Oxidation is a reaction that can produce free radicals, leading to chain reactions that may damage cells. Antioxidants such as thiols or ascorbic acid terminate these chain reactions, supplementation with selenium or vitamin E does not reduce the risk of cardiovascular disease. Oxidative stress can be considered as either a cause or consequence of some diseases, industrial antioxidants have diverse uses, such as food and cosmetics preservatives and inhibitors of rubber or gasoline deterioration. Although certain levels of antioxidant vitamins in the diet are required for good health, moreover, if they are actually beneficial, it is unknown which antioxidant are needed from the diet and in what amounts beyond typical dietary intake. Some authors dispute the hypothesis that antioxidant vitamins could prevent chronic diseases, polyphenols, which often have antioxidant properties in vitro, are not necessarily antioxidants in vivo due to extensive metabolism. In many polyphenols, the group acts as electron acceptor and is therefore responsible for the antioxidant activity. However, this catechol group undergoes extensive metabolism upon uptake in the body, for example by catechol-O-methyl transferase. Many polyphenols may have non-antioxidant roles in minute concentrations that affect cell-to-cell signaling, receptor sensitivity, tirilazad is an antioxidant steroid derivative that inhibits the lipid peroxidation that is believed to play a key role in neuronal death in stroke and head injury. It demonstrated activity in animal models of stroke, but human trials demonstrated no effect on mortality or other outcomes in subarachnoid haemorrhage, similarly, the designed antioxidant NXY-059 exhibited efficacy in animal models, but failed to improve stroke outcomes in a clinical trial. As of November 2014, other antioxidants are being studied as potential neuroprotectants, common pharmaceuticals with antioxidant properties may interfere with the efficacy of certain anticancer medication and radiation. During exercise, oxygen consumption can increase by a factor of more than 10, however, no benefits for physical performance to athletes are seen with vitamin E supplementation and 6 weeks of vitamin E supplementation had no effect on muscle damage in ultramarathon runners. Some research suggests that supplementation with amounts as high as 1000 mg of vitamin C inhibits recovery, other studies indicated that antioxidant supplementation may attenuate the cardiovascular benefits of exercise. Relatively strong reducing acids can have antinutrient effects by binding to dietary minerals such as iron and zinc in the gastrointestinal tract, notable examples are oxalic acid, tannins and phytic acid, which are high in plant-based diets. Calcium and iron deficiencies are not uncommon in diets in developing countries where meat is eaten and there is high consumption of phytic acid from beans. Nonpolar antioxidants such as major component of oil of cloves—have toxicity limits that can be exceeded with the misuse of undiluted essential oils. Toxicity associated with high doses of water-soluble antioxidants such as ascorbic acid are less of a concern, more seriously, very high doses of some antioxidants may have harmful long-term effects. The beta-carotene and Retinol Efficacy Trial study of cancer patients found that smokers given supplements containing beta-carotene
23.
Tocopherol
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Tocopherols are a class of organic chemical compounds, many of which have vitamin E activity. Tocotrienols, which are related compounds, also have vitamin E activity, Vitamin E exists in eight different forms, four tocopherols and four tocotrienols. All feature a ring, with a hydroxyl group that can donate a hydrogen atom to reduce free radicals. Both the tocopherols and tocotrienols occur in α, β, γ and δ forms, determined by the number, the unsaturation of the tails gives tocotrienols only a single stereoisomeric carbon, whereas tocopherols have 3 centers. Each form has a different biological activity, in general, the unnatural l-isomers of tocotrienols lack almost all vitamin activity, and half of the possible 8 isomers of the tocopherols also lack vitamin activity. Of the stereoisomers which retain activity, increasing methylation, especially full methylation to the alpha-form, in tocopherols, this is due to the preference of the tocopherol binding protein for the alpha-tocopherol form of the vitamin. As a food additive, tocopherol is labeled with these E numbers, E306, E307, E308 and these are all approved in the USA, EU and Australia and New Zealand for use as antioxidants. Alpha-tocopherol is the form of vitamin E that is absorbed and accumulated in humans. The measurement of vitamin E activity in units was based on fertility enhancement by the prevention of miscarriages in pregnant rats relative to alpha-tocopherol. There are three stereocenters in alpha-tocopherol, so this is a chiral molecule, the eight stereoisomers of alpha-tocopherol differ in the arrangement of groups around these stereocenters. In the image of RRR-alpha-tocopherol below, all three stereocenters are in the R form, however, if the middle of the three stereocenters were changed, this would become the structure of RSR-alpha-tocopherol. These stereoisomers can also be named in an alternative older nomenclature,1 IU of tocopherol is defined as ⅔ milligrams of RRR-alpha-tocopherol. 1 IU is also defined as 1 milligram of a mix of the eight stereoisomers. This mix of stereoisomers is often called dl-alpha-tocopheryl acetate, even though it is more precisely dl, dl, Tocotrienols, although less commonly known, also belong to the vitamin E family. Tocotrienols have four natural 2 d-isomers, tocotrienol has been subject to fewer clinical studies and seen less research as compared to tocopherol. However, there is growing interest in the effects of these compounds. During feeding experiments with rats Herbert McLean Evans concluded in 1922 that besides vitamins B and C, although every other nutrition was present, the rats were not fertile. This condition could be changed by additional feeding with wheat germ and it took several years until 1936 when the substance was isolated from wheat germ and the formula C29H50O2 was determined
24.
Gallic acid
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Gallic acid is a trihydroxybenzoic acid, a type of phenolic acid, found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. The chemical formula of gallic acid is C6H23COOH and it is found both free and as part of hydrolyzable tannins. The gallic acid groups are bonded to form dimers such as ellagic acid. Hydrolyzable tannins break down on hydrolysis to give gallic acid and glucose or ellagic acid and glucose, known as gallotannins and ellagitannins, gallic acid forms intermolecular esters such as digallic and trigallic acids, and cyclic ether-esters. Gallic acid can also be used as a material in the synthesis of the psychedelic alkaloid mescaline. The name is derived from oak galls, which were used to prepare tannic acid. Despite the name, gallic acid does not contain gallium, salts and esters of gallic acid are termed gallates. Pliny the Elder describes his experiments with it and writes that it was used to produce dyes, galls from oak trees were crushed and mixed with water, producing tannic acid. Gallic acid was one of the used by Angelo Mai, among other early investigators of palimpsests, to clear the top layer of text off. Mai was the first to employ it, but did so with a heavy hand, gallic acid was first studied by the Swedish chemist Carl Wilhelm Scheele in 1786. Gallic acid is a component of some pyrotechnic whistle mixtures, gallic acid is formed from 3-dehydroshikimate by the action of the enzyme shikimate dehydrogenase to produce 3, 5-didehydroshikimate. This latter compound tautomerizes to form the redox equivalent gallic acid, gallate dioxygenase is an enzyme found in Pseudomonas putida that catalyses the reaction gallate + O2 → -4-oxobut-1-ene-1,2, 4-tricarboxylate. Gallate decarboxylase is another enzyme in the degradation of gallic acid, gallate 1-beta-glucosyltransferase is an enzyme that uses UDP-glucose and gallate, whereas its two products are UDP and 1-galloyl-beta-D-glucose. It is a carbonic anhydrase inhibitor. In basic research, gallic acid extracted from seeds has been shown to inhibit the formation of amyloid fibrils, one of the potential causes of Alzheimers disease. One study indicated that gallic acid has this effect on amyloid protein formation by modifying the properties of alpha-synuclein, gallic acid is classified as a mutagen and a teratogen. Gallic acid is found in a number of plants, such as the parasitic plant Cynomorium coccineum, the aquatic plant Myriophyllum spicatum. Gallic acid is found in various oak species, Caesalpinia mimosoides
25.
Erythorbic acid
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Erythorbic acid is a stereoisomer of ascorbic acid. It is synthesized by a reaction between methyl 2-keto-D-gluconate and sodium methoxide and it can also be synthesized from sucrose or by strains of Penicillium that have been selected for this feature. It is denoted by E number E315, and is used as an antioxidant in processed foods. Clinical trials have been conducted to investigate aspects of the value of erythorbic acid. One such trial investigated the effects of acid on vitamin C metabolism in young women. A later study found that erythorbic acid is a potent enhancer of nonheme-iron absorption. Since the U. S. Food and Drug Administration banned the use of sulfites as a preservative in foods intended to be eaten fresh and it is also used as a preservative in cured meats and frozen vegetables. It was first synthesized in 1933 by the German chemists Kurt Maurer and Bruno Schiedt
26.
Citric acid
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Citric acid is a weak organic tricarboxylic acid having the chemical formula C6H8O7. It occurs naturally in citrus fruits, in biochemistry, it is an intermediate in the citric acid cycle, which occurs in the metabolism of all aerobic organisms. More than a million tons of acid are manufactured every year. It is used widely as an acidifier, as a flavoring and chelating agent, a citrate is a derivative of citric acid, that is, the salts, esters, and the polyatomic anion found in solution. An example of the former, a salt is trisodium citrate, when part of a salt, the formula of the citrate ion is written as C6H5O73− or C3H5O33−. Citric acid exists in greater than trace amounts in a variety of fruits and vegetables, lemons and limes have particularly high concentrations of the acid, it can constitute as much as 8% of the dry weight of these fruits. The concentrations of acid in citrus fruits range from 0.005 mol/L for oranges and grapefruits to 0.30 mol/L in lemons. Within species, these values vary depending on the cultivar and the circumstances in which the fruit was grown, wehmer discovered Penicillium mold could produce citric acid from sugar. However, microbial production of citric acid did not become important until World War I disrupted Italian citrus exports. In this production technique, which is still the major route to citric acid used today. The source of sugar is corn steep liquor, molasses, hydrolyzed corn starch or other inexpensive sugary solutions, in 1977, a patent was granted to Lever Brothers for the chemical synthesis of citric acid starting either from aconitic or isocitrate/alloisocitrate calcium salts under high pressure conditions. This produced citric acid in near quantitative conversion under what appeared to be a reverse non-enzymatic Krebs cycle reaction, in 2007, worldwide annual production stood at approximately 1,600,000 tons. More than 50% of this volume was produced in China, citric acid was first isolated in 1784 by the chemist Carl Wilhelm Scheele, who crystallized it from lemon juice. It can exist either in a form or as a monohydrate. The anhydrous form crystallizes from hot water, while the forms when citric acid is crystallized from cold water. The monohydrate can be converted to the form at about 78 °C. Citric acid also dissolves in ethanol at 15 °C. It decomposes with loss of carbon dioxide above about 175 °C, citric acid is normally considered to be a tribasic acid, with pKa values, extrapolated to zero ionic strength, of 5.21,4.28 and 2.92 at 25 °C
27.
Tartrate
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A tartrate is a salt or ester of the organic compound tartaric acid, a dicarboxylic acid. The formula of the dianion is O−OC-CH-CH-COO− or C4H4O62−. As food additives, tartrates are used as antioxidants, acidity regulators, the principal component of this deposit is potassium bitartrate, a potassium salt of tartatic acid. Small amounts of debris, dead yeast, and precipitated phenolic materials such as tannins make up the impurities contaminating the potassium acid tartrate. The wine industry is the source of commercial tartrates. Tartrates separate from new wines because they are soluble in alcohol than in non-alcoholic grape juice. The exact figures vary according to variety and region, but approximately half of the tartrate soluble in grape juice is insoluble in wine, the problem is that the tartrate may remain in a supersaturated state after bottling, only to crystallize at some unpredictable later time. Tartrates precipitated in red wine usually take on some red pigment and are dismissed as mere sediment. The modern wine industry has decided that tartrate stabilization is preferable to consumer education
28.
Malic acid
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Malic acid is an organic compound with the molecular formula C4H6O5. It is an acid that is made by all living organisms, contributes to the pleasantly sour taste of fruits. Malic acid has two forms, though only the L-isomer exists naturally. The salts and esters of malic acid are known as malates, the malate anion is an intermediate in the citric acid cycle. L-Malic acid is the naturally occurring form, whereas a mixture of L-, malate plays an important role in biochemistry. In the C4 carbon fixation process, malate is a source of CO2 in the Calvin cycle, in the citric acid cycle, -malate is an intermediate, formed by the addition of an -OH group on the si face of fumarate. It can also be formed from pyruvate via anaplerotic reactions, malate is also synthesized by the carboxylation of phosphoenolpyruvate in the guard cells of plant leaves. Malate, as an anion, often accompanies potassium cations during the uptake of solutes into the guard cells in order to maintain electrical balance in the cell. The accumulation of these solutes within the cell decreases the solute potential, allowing water to enter the cell. Malic acid was first isolated from apple juice by Carl Wilhelm Scheele in 1785, antoine Lavoisier in 1787 proposed the name acide malique, which is derived from the Latin word for apple, mālum—as is its genus name Malus. In German it is named Äpfelsäure after plural or singular of the fruit apple, Malic acid contributes to the sourness of green apples. It is present in grapes and in most wines with concentrations sometimes as high as 5 g/l and it confers a tart taste to wine, although the amount decreases with increasing fruit ripeness. The taste of malic acid is very clear and pure in rhubarb and it is also a component of some artificial vinegar flavors, such as salt and vinegar flavored potato chips. The process of malolactic fermentation converts malic acid to much milder lactic acid, Malic acid occurs naturally in all fruits and many vegetables, and is generated in fruit metabolism. Malic acid, when added to products, is denoted by E number E296. Malic acid is the source of extreme tartness in United States-produced confectionery and it is also used with or in place of the less sour citric acid in sour sweets. These sweets are sometimes labeled with a warning stating that excessive consumption can cause irritation of the mouth and it is approved for use as a food additive in the EU, US and Australia and New Zealand. Malic acid provides 10 kJ of energy per gram during digestion, racemic malic acid is produced industrially by the double hydration of maleic anhydride
29.
Succinate
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Succinic acid is a dicarboxylic acid with the chemical formula 22. The name derives from Latin succinum, meaning amber, succinate is generated in mitochondria via the tricarboxylic acid cycle, an ancient energy-yielding process shared by all organisms. As such, succinate links cellular metabolism to the regulation of cellular function, dysregulation of succinate synthesis and degradation can lead to pathological conditions, such as malignant transformation, inflammation and tissue injury. Succinic acid is a white, odorless solid with an acidic taste. In an aqueous solution, succinic acid readily ionizes to form its conjugate base, succinate. As a diprotic acid, succinic acid undergoes two successive reactions,22 → 2− + H+ 2− → 222− + H+ The pKa of these processes are 4.3 and 5.6. Both anions are colorless and can be isolated as the salts, e. g. Na2, in living organisms, primarily succinate, not succinic acid, is found. As a radical group it is called a succinyl group, like most simple mono- and dicarboxylic acids, it is not harmful but can be an irritant to skin and eyes. Succinic acid can be oxidized to fumaric acid or be converted to diesters and this diethyl ester is a substrate in the Stobbe condensation. Dehydration of succinic acid gives succinic anhydride, succinate can be used to derive 1, 4-butanediol, maleic anhydride, succinimide, 2-pyrrolidinone and tetrahydrofuran. Historically, succinic acid was obtained from amber by distillation and has thus been known as spirit of amber, today, succinic acid is generated for human use synthetically or converted from biomass via fermentation. Common industrial routes of synthesis include partial hydrogenation of maleic acid, oxidation of 1, 4-butanediol, succinate is also produced petrochemically from butane via maleic anhydride. Additionally, genetic engineering of bacteria, such as Escherichia coli or Saccharomyces cerevisiae, has allowed for the high-yielding. Global production is estimated at 16,000 to 30,000 tons a year, in 2004, succinate was placed on the US Department of Energys list of top 12 platform chemicals from biomass. Succinic acid is a precursor to polyesters and a component of some alkyd resins. A key derivative of succinic acid,1, 4-butanediol, has industrial applications. The global market size for BDO was estimated at USD4.72 billion in 2013, BDO is a precursor to the common organic solvent THF and a precursor to polybutylene terephthalate, an engineering-grade thermoplastic. The automotive and electronics industries heavily rely on PBT to produce connectors, insulators, wheel covers, gearshift knobs, Succinic acid also serves as the bases of certain biodegradable polymers, which are of interest in tissue engineering applications
30.
Fumaric acid
–
Fumaric acid or trans-butenedioic acid is the chemical compound with the formula HO2CCH=CHCO2H. This white crystalline compound is one of two isomeric unsaturated dicarboxylic acids, the other being maleic acid, in fumaric acid the carboxylic acid groups are trans and in maleic acid they are cis. Fumaric acid has a fruit-like taste, the salts and esters are known as fumarates. Fumarate can also refer to the C4H2O4−− ion, Fumaric acid was first prepared from succinic acid. A traditional synthesis involves oxidation of furfural using chlorate in the presence of a vanadium-based catalyst, currently, industrial synthesis of fumaric acid is mostly based on catalytic isomerisation of maleic acid in aqueous solutions at low pH. Maleic acid is accessible in large volumes as a product of maleic anhydride. The chemical properties of acid can be anticipated from its component functional groups. This weak acid forms a diester, it undergoes additions across the double bond, Fumaric acid does not combust in a bomb calorimeter under conditions where maleic acid deflagrates smoothly. Fumaric acid is found in fumitory, bolete mushrooms, lichen, fumarate is an intermediate in the citric acid cycle used by cells to produce energy in the form of adenosine triphosphate from food. It is formed by the oxidation of succinate by the enzyme succinate dehydrogenase, fumarate is then converted by the enzyme fumarase to malate. Human skin naturally produces fumaric acid when exposed to sunlight, fumarate is also a product of the urea cycle. Fumaric acid has been used as a food acidulant since 1946 and it is approved for use as a food additive in the EU, USA and Australia and New Zealand. As a food additive, it is used as an acidity regulator and it is generally used in beverages and baking powders for which requirements are placed on purity. As well as being a component of some artificial vinegar flavors, such as Salt and Vinegar flavored potato chips, in patients with relapsing-remitting multiple sclerosis, the ester dimethyl fumarate significantly reduced relapse and disability progression in a phase 3 trial. It activates the Nrf2 antioxidant response pathway, the primary defense against the cytotoxic effects of oxidative stress. Various Fumaric acid esters have specific immunomodulating properties which are responsible for effects in the treatment of psoriasis. In the Netherlands, Germany, Austria and the Benelux countries substances derived from fumaric acid have been used for half a century for this purpose, such studies should in the future help specify which psoriasis variants are suited to be treated with fumaric acid esters. Fumaric acid is present in the herb called Fumaria officinalis
31.
Emulsion
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An emulsion is a mixture of two or more liquids that are normally immiscible. Emulsions are part of a general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion should be used when both phases, dispersed and continuous, are liquids, in an emulsion, one liquid is dispersed in the other. Examples of emulsions include vinaigrettes, homogenized milk, mayonnaise, the word emulsion comes from the Latin word for to milk, as milk is an emulsion of fat and water, along with other components. Two liquids can form different types of emulsions, as an example, oil and water can form, first, an oil-in-water emulsion, wherein the oil is the dispersed phase, and water is the dispersion medium. Second, they can form an emulsion, wherein water is the dispersed phase. Multiple emulsions are also possible, including a water-in-oil-in-water emulsion and an oil-in-water-in-oil emulsion, emulsions, being liquids, do not exhibit a static internal structure. The droplets dispersed in the matrix are usually assumed to be statistically distributed. The term emulsion is used to refer to the photo-sensitive side of photographic film. Such a photographic emulsion consist of silver halide colloidal particles dispersed in a gelatin matrix, nuclear emulsions are similar to photographic emulsions, except that they are used in particle physics to detect high-energy elementary particles. Emulsions contain both a dispersed and a phase, with the boundary between the phases called the interface. Emulsions tend to have an appearance because the many phase interfaces scatter light as it passes through the emulsion. Emulsions appear white when all light is scattered equally, if the emulsion is dilute enough, higher-frequency and low-wavelength light will be scattered more, and the emulsion will appear bluer – this is called the Tyndall effect. If the emulsion is concentrated enough, the color will be distorted toward comparatively longer wavelengths and this phenomenon is easily observable when comparing skimmed milk, which contains little fat, to cream, which contains a much higher concentration of milk fat. One example would be a mixture of water and oil, two special classes of emulsions – microemulsions and nanoemulsions, with droplet sizes below 100 nm – appear translucent. This property is due to the fact that lightwaves are scattered by the only if their sizes exceed about one-quarter of the wavelength of the incident light. Due to their similarity in appearance, translucent nanoemulsions and microemulsions are frequently confused, the required surfactant concentration in a microemulsion is, however, several times higher than that in a translucent nanoemulsion, and significantly exceeds the concentration of the dispersed phase. Because of many undesirable side-effects caused by surfactants, their presence is disadvantageous or prohibitive in many applications, in addition, the stability of a microemulsion is often easily compromised by dilution, by heating, or by changing pH levels
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Alginate
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Alginic acid, also called algin or alginate, is an anionic polysaccharide distributed widely in the cell walls of brown algae, where through binding with water it forms a viscous gum. Its colour ranges from white to yellowish-brown and it is sold in filamentous, granular or powdered forms. The monomers can appear in homopolymeric blocks of consecutive G-residues, consecutive M-residues or alternating M, alginates are refined from brown seaweeds. A wide variety of seaweeds of the phylum Phaeophyceae are harvested throughout the world to be converted into the raw material commonly known as sodium alginate. Sodium alginate has a wide use across a variety of industries including food, textile printing. Dental impression material utilizes alginate as its means of gelling, Alginate is both food and skin safe. Seaweeds can be classified into three groups based on pigmentation, brown, red and green. These broad groups are the Phaeophyceae, Rhodophyceae and Chlorophyceae, respectively, brown seaweeds are usually large, and range from the giant kelp Macrocystis pyrifera that is often 20 m long, to thick, leather-like seaweeds from 2-4 m long, to smaller species 30–60 cm long. None of the usual seaweeds for alginate production are cultivated and they cannot be grown by vegetative means, but must go through a reproductive cycle involving an alternation of generations. This makes cultivated brown seaweeds too expensive compared to the costs of harvesting and transporting wild seaweeds. The only exception is for Laminaria japonica, which is cultivated in China for food, alginates from different species of brown seaweed often have variations in their chemical structure, resulting in different physical properties. Commercial varieties of alginate are extracted from seaweed, including the giant kelp Macrocystis pyrifera, Ascophyllum nodosum and it is also produced by two bacterial genera Pseudomonas and Azotobacter, which played a major role in the unravelling of its biosynthesis pathway. Bacterial alginates are useful for the production of micro- or nanostructures suitable for medical applications, sodium alginate is the sodium salt of alginic acid. Sodium alginate is a gum, extracted from the walls of brown algae. Potassium alginate is a compound that is the potassium salt of alginic acid. It is an extract of seaweed and its empirical chemical formula is KC6H7O6. Calcium alginate, made from sodium alginate from which the salt has been removed and replaced with calcium, has the chemical formula C12H14CaO12. The processes for the manufacture of sodium alginate from brown seaweeds fall into two categories, 1) Calcium alginate method and, 2) Alginic acid method, the chemistry of the processes used to make sodium alginate from brown seaweeds is relatively simple
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Natural gum
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Natural gums are polysaccharides of natural origin, capable of causing a large increase in a solution’s viscosity, even at small concentrations. In the food industry they are used as thickening agents, gelling agents, emulsifying agents, in other industries, they are also used as adhesives, binding agents, crystal inhibitors, clarifying agents, encapsulating agents, flocculating agents, swelling agents, foam stabilizers, etc. Most often these gums are found in the elements of plants or in seed coatings. Natural gums can be classified according to their origin and they can also be classified as uncharged or ionic polymers
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Polyethylene glycol
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Polyethylene glycol is a polyether compound with many applications from industrial manufacturing to medicine. PEG is also known as polyethylene oxide or polyoxyethylene, depending on its molecular weight, the structure of PEG is commonly expressed as H−n−OH. PEG, PEO, and POE refer to an oligomer or polymer of ethylene oxide, the three names are chemically synonymous, but historically PEG is preferred in the biomedical field, whereas PEO is more prevalent in the field of polymer chemistry. PEG and PEO are liquids or low-melting solids, depending on their molecular weights, PEGs are prepared by polymerization of ethylene oxide and are commercially available over a wide range of molecular weights from 300 g/mol to 10,000,000 g/mol. Lower-molecular-weight PEGs are also available as purer oligomers, referred to as monodisperse, uniform, very high purity PEG has recently been shown to be crystalline, allowing determination of a crystal structure by x-ray diffraction. Since purification and separation of pure oligomers is difficult, the price for this type of quality is often 10–1000 fold that of polydisperse PEG, PEGs are also available with different geometries. Branched PEGs have three to ten PEG chains emanating from a core group. Star PEGs have 10 to 100 PEG chains emanating from a core group. Comb PEGs have multiple PEG chains normally grafted onto a polymer backbone, most PEGs include molecules with a distribution of molecular weights. The size distribution can be characterized statistically by its weight average molecular weight and its number average molecular weight, MW and Mn can be measured by mass spectrometry. PEGylation is the act of covalently coupling a PEG structure to another molecule, for example, a therapeutic protein. PEGylated interferon alfa-2a or −2b are commonly used injectable treatments for hepatitis C infection, PEG is soluble in water, methanol, ethanol, acetonitrile, benzene, and dichloromethane, and is insoluble in diethyl ether and hexane. It is coupled to hydrophobic molecules to produce non-ionic surfactants, PEGs contain potential toxic impurities, such as ethylene oxide and 1, 4-dioxane. Ethylene Glycol and its ethers are nephrotoxic if applied to damaged skin, polyethylene glycol and related polymers are often sonicated when used in biomedical applications. However, as reported by Murali et al, PEG is very sensitive to sonolytic degradation and PEG degradation products can be toxic to mammalian cells. It is, thus, imperative to assess potential PEG degradation to ensure that the material does not contain undocumented contaminants that can introduce artifacts into experimental results. PEGs and methoxypolyethylene glycols are manufactured by Dow Chemical under the tradename Carbowax for industrial use and they vary in consistency from liquid to solid, depending on the molecular weight, as indicated by a number following the name. Some specific groups are lauromacrogols, nonoxynols, octoxynols, and poloxamers, macrogol, used as a laxative, is a form of polyethylene glycol
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Cellulose
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Cellulose is an organic compound with the formula n, a polysaccharide consisting of a linear chain of several hundred to many thousands of β linked D-glucose units. Cellulose is an important structural component of the cell wall of green plants, many forms of algae. Some species of bacteria secrete it to form biofilms, Cellulose is the most abundant organic polymer on Earth. The cellulose content of cotton fiber is 90%, that of wood is 40–50%, Cellulose is mainly used to produce paperboard and paper. Smaller quantities are converted into a variety of derivative products such as cellophane. Conversion of cellulose from energy crops into biofuels such as ethanol is under investigation as an alternative fuel source. Cellulose for industrial use is mainly obtained from wood pulp and cotton, some animals, particularly ruminants and termites, can digest cellulose with the help of symbiotic micro-organisms that live in their guts, such as Trichonympha. In humans, cellulose acts as a bulking agent for feces and is often referred to as a dietary fiber. Cellulose was discovered in 1838 by the French chemist Anselme Payen, Cellulose was used to produce the first successful thermoplastic polymer, celluloid, by Hyatt Manufacturing Company in 1870. Production of rayon from cellulose began in the 1890s and cellophane was invented in 1912, hermann Staudinger determined the polymer structure of cellulose in 1920. The compound was first chemically synthesized in 1992, by Kobayashi, Cellulose has no taste, is odorless, is hydrophilic with the contact angle of 20–30 degrees, is insoluble in water and most organic solvents, is chiral and is biodegradable. It was shown to melt at 467 °C in 2016 and it can be broken down chemically into its glucose units by treating it with concentrated mineral acids at high temperature. Cellulose is derived from D-glucose units, which condense through β-glycosidic bonds and this linkage motif contrasts with that for α-glycosidic bonds present in starch and glycogen. This confers tensile strength in cell walls, where cellulose microfibrils are meshed into a polysaccharide matrix, compared to starch, cellulose is also much more crystalline. Whereas starch undergoes a crystalline to amorphous transition when heated beyond 60–70 °C in water, cellulose requires a temperature of 320 °C, several different crystalline structures of cellulose are known, corresponding to the location of hydrogen bonds between and within strands. Natural cellulose is cellulose I, with structures Iα and Iβ, Cellulose produced by bacteria and algae is enriched in Iα while cellulose of higher plants consists mainly of Iβ. Cellulose in regenerated cellulose fibers is cellulose II, the conversion of cellulose I to cellulose II is irreversible, suggesting that cellulose I is metastable and cellulose II is stable. With various chemical treatments it is possible to produce the structures cellulose III, many properties of cellulose depend on its chain length or degree of polymerization, the number of glucose units that make up one polymer molecule
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Fatty acid
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In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with a long aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms. Fatty acids are derived from triglycerides or phospholipids. Fatty acids are important dietary sources of fuel for animals because, many cell types can use either glucose or fatty acids for this purpose. Fatty acids that have double bonds are known as unsaturated. Fatty acids without double bonds are known as saturated and they differ in length as well. Fatty acid chains differ by length, often categorized as short to very long, short-chain fatty acids are fatty acids with aliphatic tails of five or fewer carbons. Medium-chain fatty acids are fatty acids with aliphatic tails of 6–12 carbons, long-chain fatty acids are fatty acids with aliphatic tails of 13 to 21 carbons. Very long chain fatty acids are fatty acids with aliphatic tails of 22 or more carbons, unsaturated fatty acids have one or more double bonds between carbon atoms. The two carbon atoms in the chain that are next to either side of the double bond can occur in a cis or trans configuration. Cis A cis configuration means that the two atoms adjacent to the double bond stick out on the same side of the chain. The rigidity of the double bond freezes its conformation and, in the case of the cis isomer, causes the chain to bend, the more double bonds the chain has in the cis configuration, the less flexibility it has. When a chain has many cis bonds, it becomes quite curved in its most accessible conformations, for example, oleic acid, with one double bond, has a kink in it, whereas linoleic acid, with two double bonds, has a more pronounced bend. α-Linolenic acid, with three bonds, favors a hooked shape. Trans A trans configuration, by contrast, means that the adjacent two hydrogen atoms lie on opposite sides of the chain, as a result, they do not cause the chain to bend much, and their shape is similar to straight saturated fatty acids. In most naturally occurring unsaturated fatty acids, each bond has three n carbon atoms after it, for some n, and all are cis bonds. Most fatty acids in the configuration are not found in nature and are the result of human processing. Fatty acids that are required by the body but cannot be made in sufficient quantity from other substrates
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PH
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In chemistry, pH is a numeric scale used to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the base 10 logarithm of the concentration, measured in units of moles per liter. More precisely it is the negative of the logarithm to base 10 of the activity of the hydrogen ion, solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. Pure water is neutral, at pH7, being neither an acid nor a base, contrary to popular belief, the pH value can be less than 0 or greater than 14 for very strong acids and bases respectively. The pH scale is traceable to a set of standard solutions whose pH is established by international agreement, the pH of aqueous solutions can be measured with a glass electrode and a pH meter, or an indicator. In the first papers, the notation had the H as a subscript to the p, as so. The exact meaning of the p in pH is disputed, but according to the Carlsberg Foundation and it has also been suggested that the p stands for the German Potenz, others refer to French puissance. Another suggestion is that the p stands for the Latin terms pondus hydrogenii, potentia hydrogenii and it is also suggested that Sørensen used the letters p and q simply to label the test solution and the reference solution. Currently in chemistry, the p stands for decimal cologarithm of, PH is defined as the decimal logarithm of the reciprocal of the hydrogen ion activity, aH+, in a solution. P H = − log 10 = log 10 For example and this definition was adopted because ion-selective electrodes, which are used to measure pH, respond to activity. For H+ number of electrons transferred is one and it follows that electrode potential is proportional to pH when pH is defined in terms of activity. The reference electrode may be a silver chloride electrode or a calomel electrode, the hydrogen-ion selective electrode is a standard hydrogen electrode. Reference electrode | concentrated solution of KCl || test solution | H2 | Pt Firstly, the cell is filled with a solution of hydrogen ion activity. Then the emf, EX, of the cell containing the solution of unknown pH is measured. PH = pH + E S − E X z The difference between the two measured emf values is proportional to pH and this method of calibration avoids the need to know the standard electrode potential. The proportionality constant, 1/z is ideally equal to 12.303 R T / F the Nernstian slope, to apply this process in practice, a glass electrode is used rather than the cumbersome hydrogen electrode. A combined glass electrode has a reference electrode. It is calibrated against buffer solutions of hydrogen ion activity
