Continuous Production of Lactic Acid from Whey Perméate by Free and Calcium Alginate Entrapped Lactobacillus helveticus

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Abstract
L. helveticus strain milano was used for the continuous fermentation of lactic acid in cheese whey-yeast extract permeate medium. The best productivity of lactic acid was with the free cell system, which was 9.7 g.L per h at a dilution rate of .352 h-1. Under such conditions, lactose conversion was 87.5%, based on the lactose concentration of 37.4 g/L in feed. Under high dilution rates, the cells were elongated to several times their normal size, resulting in wall growth. The cell growth on the fermentor wall caused system instability; however, it prevented cell wash-out under high dilution rates. The packed bed column system using Ca alginate entrapped cells is not suitable for practical application. Nonuniform pH control, plugging of the column by leaked cells, and decalcification of Ca alginate beads were major drawbacks of the packed bed system.