Whey Liquid Waste of the Dairy Industry as Raw Material for Potable Alcohol Production by Kefir Granules

• Published in: Journal of agricultural and food chemistry 2002-12, Vol.50 (25), p.7231-7234
• Main Authors: Athanasiadis, I, Boskou, D, Kanellaki, M, Kiosseoglou, V, Koutinas, A. A
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Dairying; Ethanol - metabolism; Fermentation; Food industries; Fundamental and applied biological sciences. Psychology; Industrial Waste; Kinetics; Milk - metabolism; Milk and cheese industries. Ice creams; Milk Proteins; Molasses; Whey Proteins
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf020331q

Kefir granular biomass was used in the fermentation of sweet whey and proved to be more effective compared to single-cell biomass of kefir yeast. The operational stability of the biocatalyst was assessed by carrying out 20 repeated batch fermentations. Levels of ethanol productivity reached 2.57 g L-1 h-1, whereas the yield was 0.45 g/g. The fermentation time was only 8 h. Mixtures of sweet whey with molasses were fermented at initial densities ranging from 4.2 to 10.2 °Be and resulted in ethanol yield factors between 0.36 and 0.48 g of ethanol/g of utilized sugar. Lower °Be values led to an increase of percentages of ethyl acetate on total volatiles determined and a reduction of amyl alcohols. The addition of 1% black raisin extract to whey appears to promote whey fermentation, whereas the same was not observed in the case of white sultana extract addition. It was finally established that it is preferable to ferment mixtures of whey−molasses by adding molasses in whey after the completion of whey fermentation. Keywords: Kefir; granules; fermentation; whey; molasses