Baker's Yeast
பேக்கர்ஸ் ஈஸ்ட்
Do not mistake fermentation for mere cooking. It is a metabolic pathway, specifically anaerobic respiration, occurring in the cytoplasm of Saccharomyces cerevisiae. If you confuse this with aerobic respiration, you lose marks.
The idea
Saccharomyces cerevisiae, or baker's yeast, is a unicellular fungus used in the fermentation of dough. During this process, the yeast metabolizes sugars to produce ethanol and carbon dioxide. The CO2 gas gets trapped in the dough, causing it to puff up and increase in volume.
Why it matters
Yeast performs anaerobic respiration (fermentation) to generate energy, releasing CO2 as a metabolic byproduct which aerates the dough.
NEET lens
NEET focuses on the product of fermentation: CO2. Remember, the 'puffed-up' appearance is strictly due to CO2, not ethanol. Expect questions linking this to the 'Microbes in Human Welfare' chapter; memorize the scientific name correctly.
Clinical significance
Yeast fermentation is essential for gut health, as it produces B-vitamins and aids in the breakdown of complex carbohydrates. However, an overgrowth of Candida species, a related yeast, can lead to candidiasis, a common opportunistic infection in immunocompromised patients.
Introduction
Saccharomyces cerevisiae, commonly called baker's yeast, is used to ferment dough for making bread and to produce ethanol and beverages.
Core concept
Uses (NCERT): dough used for making bread is fermented using baker's yeast; CO2 produced makes the bread puffy. Saccharomyces cerevisiae is also used for the commercial production of ethanol. Brewer's yeast (the same species) is used for fermenting malted cereals and fruit juices to produce alcoholic beverages; wine and beer are produced without distillation, whereas whisky, brandy and rum are produced by distillation of the fermented broth.
Go deeper
Yeast is a unicellular fungus; it respires anaerobically to produce ethanol and CO2 — the basis of fermentation.
From Class 10
The yeast used in bakeries makes bread rise by releasing gas while it feeds on sugar in the dough.