ETHANOL-PRODUCTION FROM SALT WHEY USING FREE AND AGAROSE IMMOBILIZED YEASTS

Salt whey permeate was used as a substrate for ethanol production by salt-tolerant yeast in conventional, "rapid" and immobilized cell batch systems. In the cell suspension system Kluyveromyces fragilis was selected as the most efficient strain of the 5 yeast strains under test. Entrapment of stationary phase of K. fragilis in 1.5 % agar substantially improved the activity of the cells. Immobilized K. fragilis produced 2.5-2.6 % alcohol from whey permeate salted to 8 % salt after 60 h of fermentation. These values amount to 75.5-78.5 % of the theoretical yields. Though the agar matrix leached a substantial quantity of cells to the medium, it retained its structure and dimensional stability during 120 h of operation in 10 % salt medium.