Production of Red Wine Using Saccharomyces cerevisiae by Controlled Alcoholic Fermentation
Aim: To produce red wine by fermenting grape must using Saccharomyces cerevisiae under controlled laboratory conditions.
Principle
Red wine fermentation is a biochemical tug-of-war—yeast wants energy, we want ethanol and color. Looking at it this way, Saccharomyces cerevisiae channels glucose and fructose through glycolysis, then decarboxylates pyruvate into ethanol and CO₂. At the same time, prolonged skin contact releases anthocyanins and tannins; skip this and you get pink disappointment. This leads to an interesting point—temperature governs enzyme kinetics and pigment stability together. Oxygen? Only at the start. pH stays acidic to choke contaminants. Sugar level decides alcohol strength. Control the environment, and yeast behaves. Ignore it—why even start?
Requirements
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Red Grape
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Saccharomyces cerevisiae culture
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Sucrose
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Tartaric acid
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Potassium metabisulfite
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Distilled water
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250 ml conical flask
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Cotton plug and airlock
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Autoclave
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pH meter or pH paper
Exact Media Composition for 100 ml Must
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Grape juice (with skins) — 80 ml
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Distilled water — 20 ml
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Sucrose — 5-10 g
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Tartaric acid — 0.2 g
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Potassium metabisulfite — 0.01 g
Procedure:
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Prepare 100 ml of grape must using the above composition and adjust pH to 3.4.
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Transfer the must into a clean conical flask and loosely plug with cotton.
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Pasteurize the must at 110°C for 10 minutes and cool it to room temperature without shaking.
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Inoculate the cooled must with 5 ml of actively growing Saccharomyces cerevisiae culture.
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Fit an airlock immediately—oxygen now becomes the enemy.
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Incubate the flask at 25°C for 7–10 days in a dark place without disturbance.
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Observe daily for CO₂ release and color deepening—no bubbles means failed yeast.
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After fermentation stops, filter the wine to remove yeast and skin residues.
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Store the clarified red wine at 10–15°C for settling and stabilization.
Observation: Active bubbling appears within 24–48 hours, strong alcoholic odor develops, and deep red coloration intensifies due to skin extraction.
Results: The experiment is successfully performed, yielding red wine containing ethanol, stable red pigments, and characteristic fermented aroma produced by Saccharomyces cerevisiae.
Conclusion: Red wine is produced successfully through controlled alcoholic fermentation where sugar concentration, pH, oxygen exposure, and temperature are tightly regulated—yeast rewards discipline, not guesswork.
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