Process for preparing high yields of single cell products having reduced purine content and high nutritive value

A process for substantially reducing the purine content while increasing the yield and nutritive value of single-cell protein material, intended for use in food products and derived from unicellular microorganisms grown in a fermentor aerobically in a suitable fermentation broth, comprising the steps of:

• a. preparing an aqueous cell cream containing from 10 to 14 wt.% (dry basis) of single-cell protein material;
• b. heating the cell cream to a temperature within the range from about 70.degree. to about 90.degree.C. for a period of about 5 to about 10 minutes;
• c. centrifuging the heated cell cream to provide (1) a supernatant aqueous phase and (2) a heat-treated cell concentrate;
• d. adding water to the heat-treated cell concentrate from step (c) (2) to provide an aqueous cell cream containing from 10 to 14 wt.% (dry basis) of single-cell protein material;
• e. maintaining the pH of the aqueous cell cream provided in step (d) at a pH of about 8.5 to about 10.0 by adding a base solution as needed, and heating the cell cream to a temperature within the range from about 85.degree. to 95.degree.C. for a period of about 5 to about 30 minutes;
• f. centrifuging the aqueous cell cream of step (e) to provide (1) a supernatant and (2) a treated cell concentrate, having substantially reduced purine content;
• g. adjusting the pH of the cell concentrate provided in step (f)(2) to about 7.0 by adding hydrochloric acid;
• h. washing the pH adjusted cell concentrate of step (g) with water by centrifugation;
• i. combining (1) the water-washed heat-treated cell concentrate produced in step (h) with (2) the supernatant aqueous phase produced in step (c)(1);
• and
• j. drying the mixture of step (i) to give a reconstituted product.