Continuous Whey Fermentation Using Kefir Yeast Immobilized on Delignified Cellulosic Material

• Published in: Journal of agricultural and food chemistry 2002-04, Vol.50 (9), p.2543-2547
• Main Authors: Kourkoutas, Y, Psarianos, C, Koutinas, A. A, Kanellaki, M, Banat, I. M, Marchant, R
• Format: Article
• Language: English
• Subjects: Alcoholic beverages and cider; Animals; Biological and medical sciences; Bioreactors; Cellulose; Ethanol - metabolism; Fermentation; Fermented food industries; Food industries; Fundamental and applied biological sciences. Psychology; Milk - microbiology; Milk Proteins - metabolism; Odorants; Use and upgrading of agricultural and food by-products. Biotechnology; Volatilization; Whey Proteins; Yeasts - metabolism
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf0113427

Delignified cellulosic-supported biocatalyst, prepared by immobilization of kefir yeast on delignified cellulosic material (DCM), was found to be suitable for continuous, modified whey fermentation. The modified whey contained 1% raisin extract and molasses. Ethanol productivities ranged from 3.6 to 8.3 g L-1day-1, whereas parameters such as ethanol concentration, residual sugars, and daily fermented whey productivity were acceptable for the production of potable alcohol and alcoholic drinks in industrial fermentations. The continuous fermentation bioreactor was operated for 39 days, stored for 18 days at 4 °C, and operated again for another 15 days without any diminution of the ethanol productivity. The concentrations of higher alcohols (propanol-1, isobutyl alcohol, and amyl alcohols) were low. The main volatile byproducts formed in the continuous process were similar to those observed in alcoholic beverages, and the fermented whey had a good aroma. The concentrations of higher alcohols were very low when compared to that of ethyl acetate, therefore resulting in a quality product. The possibility of using such a process for the production of potable alcohol or a novel, low-alcohol content drink is proposed. Keywords: Whey; continuous fermentation; delignified cellulosic material; immobilized cells; kefir; alcoholic drinks