Disposal of cottage cheese whey by microbial degradation

Whey disposal is a common problem among dairy plants. In recent years much research has been conducted to relieve this worrisome problem by using microorganisms. The purpose of this study was to further investigate the possibility of using microbes to reduce the Chemical Oxygen Demand (COD) of cottage cheese whey. The organisms considered in this study were Kluyveromyces fragilis (K) (formerly Saccharomyces fragilis) and Candida lipolytica (C).

The two starter cultures were added singly and in combination to make 3 different culture treatments. . A 10 percent inoculum of the culture treatments was added to l800 milliliters of whey. The cultures were grown for 48 hours in a New Brunswick Multigen fermenter at 32° C ± 2° C with constant agitation and aeration. Samples were removed at 3, 6, 12, 24, and 48 hour intervals, analyzed for pH and total solids, and then centrifuged. The supernatant was then used for COD, protein, lactose, precipitated solids and titratable acidity analysis. The effects of culture treatment and time and replications within cultures were studied. An analysis of variance was used to derive regression equations which demonstrated changes in each parameter.

There was no significant difference among culture treatments on the parameters COD and protein. There was a significant interaction between time and lactose utilization. Treatment three (K and C) was shown to respond best by reducing the organic content which resulted in a reduction of the COD of whey. In one trial (K), up to 81 percent of the lactose was utilized which reduced the COD by 86 percent. In all trials the pH and titrable acidity were virtually unchanged due to the addition of K₂HPO₄.