PRODUCTION OF ACETIC AND PROPIONIC ACIDS FROM LABNEH WHEY BY FERMENTATION WITH PROPIONIBACTERIA

Whey produced during the manufacture of Iabneh was supplemented with y east extract (10 g/l), and then fortified with lactose, treated with b eta-galactosidase or fermented with Lactobacillus helveticus, prior to inoculation with free living cells of Propionibacterium freudenreichi i ssp shermanii ol Propionibacterium acidipropionici of cells immobili zed in aliginate beads. Under anaerobic batch conditions, fermentation of the whey with Lb helveticus followed by P acidipropionici (free ce ll system) for 2.5 days at 32 degrees C gave a broth with 5.9 g/l of p ropionic acid and 2.4 g/l of acetic acid, while immobilized cells of t he same organisms gave a broth with 11.0 g/l propionic acid and 3.2 g/ l acetic acid over 4 days. These latter values were the maximum levels recorded with any of the treatments, and it is suggested that such yi elds might make recovery economically feasible in certain countries.