Encapsulation of Brewing Yeast in Alginate/chitosan Matrix: Comparative Study of Beer Fermentation with Immobilized and Free Cells

V. NAYDENOVA, V., S. VASSILEV, M. KANEVA and G. KOSTOV, 2013. Encapsulation of brewing yeast in alginate/ chitosan matrix: comparative study of beer fermentation with immobilized and free cells. Bulg. J. Agric. Sci., Supplement 2, 19: 123–127 In the present study, the possibilities for beer production with lager brewing yeasts, encapsulated in alginate/chitosan matrix with a liquid core, were investigated. The yeast cells – free and immobilized – were used for batch fermentations at 15°C. The dynamics of the fermentation parameters – yeast growth, real extract and alcohol – were studied at different original wort gravity – 9 to 17°P. Simultaneously, the dynamics of fl avor-active yeast by-products (esters, aldehydes and higher alcohols) were investigated. The immobilized cells showed higher real degree of fermentation and produced slightly higher levels of total fusel alcohols and esters. On the other hand, the free cells produced slightly higher levels of aldehydes. Fermentation kinetics was described using Monod equation. The immobilized cells showed higher specifi c growth rate and higher specifi c ethanol production rate for most of the studied variants. The results showed that cell immobilization did not affect the fermentation process and yeast by-products formation. The obtained data about the fermentation dynamics will be used for the development of a continuous system for beer production with immobilized cells.