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The growth of yeast within food products is often seen on their surfaces, as in cheeses or meats, or by the fermentation of sugars in beverages, such as juices, and semiliquid products, such as syrups and jams. [123] The yeast of the genus Zygosaccharomyces have had a long history as spoilage yeasts within the food industry.
Saccharomyces cerevisiae (/ ˌ s ɛr ə ˈ v ɪ s i. iː /) (brewer's yeast or baker's yeast) is a species of yeast (single-celled fungal microorganisms). The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have been originally isolated from the skin of grapes.
The effect was described by Louis Pasteur in 1857 in experiments showing that aeration of yeasted broth causes cell growth to increase while the fermentation rate decreases, based on lowered ethanol production. [4] [5]
In a second experiment, Pasteur used the same flasks and sugar-yeast mixture, but left it idle in 'swan-neck' flasks instead of introducing any extraneous matter. Some flasks were kept open to the common air as the control group, and these exhibited mold and microbial growths within a day or two.
petite (ρ–) is a mutant first discovered in the yeast Saccharomyces cerevisiae.Due to the defect in the respiratory chain, 'petite' yeast are unable to grow on media containing only non-fermentable carbon sources (such as glycerol or ethanol) and form small colonies when grown in the presence of fermentable carbon sources (such as glucose).
An agar plate is a Petri dish that contains a growth medium solidified with agar, used to culture microorganisms. Sometimes selective compounds are added to influence growth, such as antibiotics. [1] 96 pinner used to perform spot assays with yeast, fungal or bacterial cells
For example, in 1858, Pasteur wrote a paper trying to disprove Liebig's theory that fermentation cannot be caused by the growth of the yeast when it takes place when yeast is added to pure sugar-water. Pasteur thought that in pure sugar-water, yeast was both growing and disintegrating, and developed experiments to support his theories.
YEPD or yeast extract peptone dextrose, also often abbreviated as YPD, is a complete medium for yeast growth. It contains yeast extract, peptone, double-distilled water, and glucose (dextrose). [1] It can be used as solid medium by including agar. The yeast extract will typically contain all the amino acids necessary for growth.