Preparation of Baker’s Yeast from molasses

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Baker’s yeast consists of dried cells of few strains of fungus Saccharomyces cerevisiae and is one of the commercial preparations utilized in baking as a leavening. Yeast is a living microorganism that helps in conversion of sugar or starch to alcohol and carbon dioxide and this is the reason it is liked by most of the brewers of beer, bread bakers and the wine makers. Baker’s yeast is either active dry yeast or squashed fresh yeast. In the other hand, brewer’s yeast is non leavening yeast that is mainly used for brewing of beer and can be consumed as a food supplement because of its good properties. Saccharomyces cerevisiae is one of the top fermenting yeast and is one of the major type of yeast that is used for beer brewing and it is called so because during the process of fermentation it rises up to the top of the vessel.

The main objective of this experiment is to study how to prepare baker’s yeast from molasses.

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Chemicals:  Phosphoric acid (phosphorus)

Urea salts or NH3 salts for nitrogen

Molasses for sugars

Magnesium sulphate

Iron sulphate

Calcium sulphate

Zinc sulphate

Culture:       Pure culture of S. cerevisiae

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Sugarcane or the beet molasses are one of the main raw materials used in production of Bakers yeast is it provides the required sugar as well as energy with required nitrogen for yeast growth. Cane molasses and beet molasses are the main carbon source that helps in growth of yeast. Molasses contains 45 -55% fermentable sugars, in form of sucrose, fructose and glucose.

At first dilute the concentrated molasses with water, clarify it and heat sterilize before it is fed to yeast. Then begins the fermentation process that begins by preparing pure culture of the desired strain. Inoculate it in a sterile flask of media broth and then from vessel transfer it to a large vessel and then pass it through various fermentation stages of enhanced volumes.1

The yeast broth in the fermentor with 5% solid is allowed to get concentrated in a centrifuge to make it about 18% solid and then wash it with water. Allow this liquid to cool down and then pass it through a filter that helps in removal of water and enhances the concentration of the solid to 30%. After you are done with filtration adds small amounts of emulsifiers or oils that helps in extrusion, cutting and enhancing the performance of yeast appearance.2

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It is one of the best methods for preparation of Baker’s yeast from molasses.

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  1. S. L. Chen and M. Chigar, “Production of Baker’s Yeast”, Comprehensive Biotechnology, Volume 20, Pergamon Press, New York, NY, 1985.
  2. G. Reed and H. Peppler, Yeast Technology, Avi Publishing Company, Westport, CT, 1973.