MEASUREMENT OF HEAT GENERATED BY MIXING DURING THE BATCH-PRODUCTION OF SINGLE CELL PROTEIN FROM CHEESE WHEY

A procedure for measuring the rate of heat production from fermentation systems has been developed. The heat generated by mixing and lactose metabolism during the batch production of single cell protein from cheese whey lactose was calculated using a heat balance equation. The technique presented accounts for all the heat produced in and lost from the fermentation unit. Most of the heat generated by mixing in the cell-free system (98.93%) was lost with exhaust gas while a very small amount (1.07%) was lost through the fermenter lid, wall, and bottom. The heat generated by mixing was 26% of the total heat generated in the fermentation system with an active yeast population present. The heat produced by lactose metabolism depended on the yeast cell number. A maximum yeast population size of 820 million cells/mL and a lactose removal efficiency of 97% were observed. About 93% of the lactose consumed was used for growth. A yield of 0.78 g of cells/g of lactose was achieved.