Semi Continuous Fermentation & Significance of Fermentation

Semi continuous fermentation is defined as the fermentation process in which the substrate is added and the product removed at intervals. It combines some of the features of batch and continuous fermentation. In semi-continuous cultures, a fixed volume of the fermented medium is usually taken out from the fermentation vessel, and the same volume of nutrients is simultaneously added to the fermenter – in order to keep the volume of the fermentation medium at the same level as well as replenish the depleted nutrients for microbial growth. Semi-continuous fermentation process can be used to maintain the microorganisms in the same phase of growth over some period of time.

SIGNIFICANCE OF FERMENTATION

  • Fermentation increases the shelf-life of a finished product.
  • It improves the varieties of tastes and flavours of finished products.
  • It improves the nutritional value of foods and beverages.
  • It decreases the toxicity of finished products.
  • It improves the therapeutic value of finished products. For example, some fermented products such as yoghurts contain some beneficial microbes that improve the health status of the gut flora; and this goes a long way in improving the general health of the body.
  • Fermentation increases digestibility in the host when fermented finished foods are consumed.
  • Fermentation processes produce substances such as acids and alcohols that inhibit the overgrowth of spoilage and pathogenic microbes in the food.
  • Fermentation processes produce industrially useful end-products such as organic acids, alcohols, citric acid, alkaloids, aldehydes and ketones that are used for the production of other important products. For example, citric acid is used in the food industry, in medicine, in pharmacy and in various other industries. It is used in the food industry for example, as a major food acidulant used in the manufacture of soft drinks and sweets. It is used in medicine as sodium citrate in blood transfusion to prevent blood clotting. Citric acid has a low pH, and thus it is used in hair rinses, after shave lotions and in wig setting fluids.

References

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Steele D.B and Stowers M.D (1991). Techniques for the Selection of Industrially Important Microorganisms. Annual Review of Microbiology, 45:89-106.

Summers W.C (2000). History of microbiology. In Encyclopedia of microbiology, vol. 2, J. Lederberg, editor, 677–97. San Diego: Academic Press.

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