Yeast extracts consist of the cell contents of yeast without the cell walls; they are used as food additives or flavorings, or as nutrients for bacterial culture media. They are often used to create savory flavors and umami taste sensations and can be found in a large variety of packaged food including frozen meals, crackers, snack foods, gravy, stock and more. They are rich in B vitamins. Yeast extracts and fermented foods contain glutamic acid, an amino acid which adds an umami flavor. Glutamic acid is found in meat, cheese, fungi and vegetables—such as broccoli and tomatoes. A number of other substances found in yeast extract provide aromas, some meat-like, when allowed to react under heat.
Yeast extract
Yeast extract is a common ingredient in commercially prepared soups (canned, frozen, or deli). It is a flavor enhancer like monosodium glutamate (MSG).
Cenovis on bread, with jar in the background
Image: Vegemite (15908411205)
A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation or small plants like the moss Physcomitrella patens. Different types of media are used for growing different types of cells.
An agar plate – an example of a bacterial growth medium*: Specifically, it is a streak plate; the orange lines and dots are formed by bacterial colonies.
US Food and Drug Administration scientist tests for Salmonella
A culture of salmonella bacteria
Physcomitrella patens plants growing axenically on agar plates (Petri dish, 9 cm diameter)
