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Project for the production of yeast and yeast extracts from whey

Giuseppe Marchionni

 The whey is pasteurized at a temerature of 80 ° C for 5 minutes. The pasteurized product is placed in an aerobic fermenter in which kluyveromices marxianus, a lactic yeast, grows using lactose.

Fermentation takes place at a temperature of 30 ° C and pH 5.0. The consumption rate of the lactose substrate is as follows: 6.0 kg of lactose per hour/cubic meter of fermenter. The conversion yields are: kg of dry yeast per kg of lactose used kg 0.50 (yield 50%)   Since whey has 5.0% lactose (intended as an average value), there is the following production potential: Volume of fermented whey per cubic meter of fermenter per hour:mc 0.12   The fermented broth is centrifuged then the 30% dry yeast cream is separated. The cream is dried using a spray dryer to obtain the yeast flour. As an alternative to the production of yeast flour, the cream can be subjected to "enzymatic autolysis": in this process, the yeast proteins hydrolyze to form amino acids. The hydrolyzate product is centrifuged to separate: - amino acid solution; - solid yeast cell walls.