Food fermentation
PHOTO: K. ANANTHAN
Which food types are easily fermented?
C. KARTHIKEYAN
Madurai, Tamil Nadu
Fermentation is the process of conversion of sugar into alcohols or organic acids by the microorganisms like the yeast, in anaerobic conditions referring to absence of plenty of oxygen. This process also produces heat and copious amounts of carbon dioxide as by-products. This being a biochemical process, it occurs in specific temperature conditions. Too low or too high temperatures terminate fermentation.
In industries, fermentation processes are utilized for various benefits. In the biochemical and pharmaceutical industries, many products are produced by this process.
The process of fermentation is adopted in preparation of a variety of food products such as bread, curd and yoghurts, wine, beer, pickles etc. The raw ingredients are made mixed with large amount of water in order to facilitate the action of the microbes, which ferment the sugar. In all of them the sugar and starch content of the food get fermented.
For preparation of wine, the fully ripe grapes are crushed into a pulpy mass and this is diluted with water followed by addition of yeast. This is stored in closed casks where fermentation takes place over several days, resulting in wine that is decanted out. Similarly, beer is fermented from mixture of partly crushed grains and water.
The food items with large amount of sugar and starch easily undergo fermentation. Dough made from refined wheat flour is fermented for few hours when the carbon dioxide generated converts the dough into a spongy mass. This is then baked to prepare bread.
In the formation of curd, the lactose sugar of the milk is consumed by the bacterial fermentation producing lactic acid, which gives the sour tang to the curd. Similarly, the acid produced by the dominant bacteria, inhibit the growth of all other microorganisms, helping in preservation over long periods of time.
Dr. H. K. SAHU
Scientific Officer
Indira Gandhi Centre for Atomic Research
Kalpakkam,
Tamil Nadu
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