Dried Inactive Yeast Powder

An inevitable and commercially important byproduct of fermentation processes is yeast. This can be recovered, dried, and inactivated to form a valuable food ingredient. Although the brewing industry is the major source, the demand is sufficient to warrant the growing of selected yeasts primarily for this purpose. Henry [63] has described the production of dried Torula yeast, resulting from the fermentation of the waste sulfite liquors from paper production. 

The yeast slurry, containing about 1% solids, is continuously separated from the substrate by centrifuging, the collected yeast cells are washed to remove all adhering chemicals and then dried to a moisture content of 7% to give the commercial product. This product has a very high protein content (min. 45%) and substantial amounts of B vitamins. The USE XIII confines the source to either S. cerevisiae or Candida utilis. 

Dried inactive yeasts are used not only as valuable nutrient and vitamin supplements but in the flavoring of dry savory seasonings, dip mixes, gravy and sauce mixes, snack products, etc., to which they give a rich, full-bodied flavor character. Because of the many variables that affect the flavor profile of inactivated yeast, the products of different manufacturers have quite distinctive flavoring properties. The profile may be characterized by such nuances as sweet, caramel-like, roasted, beefy, cheesey, or creamy, and this implies that such products must be individually assessed prior to use. 

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The inactive brewery yeast suspension as the by-product of the beer production contains vitamin B and trace elements in relatively high concentration therefore the dried powder, after tabletting can be circulated as roborant. It was very important to preserve its vitamin content whereas the moisture content of the dried product should be less than 5% m/m moreover, the particle size of 90% of the product should be smaller than 0.4 mm and the size of remains should not exceed 1 mm. 

Removal of glucose has been used successfully in the production of powdered (dried) whole eggs and egg whites. Glucose is oxidised to inactive gluconic acid by the addition of a yeast preparation with glucose oxidase activity, or by the addition of glucose oxidase enzyme. Simultaneous removal of oxygen slows down the autoxidation reaction. 

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