Impact of saccharification method on barley mash fermentation parameters and quality of fermented mash

UDC 663.5

Impact of saccharification method on barley mash fermentation parameters and quality of fermented mash

Ustinova A S, MELEDINA T.V., Barakova N.V., Natchetova M.F., Gomes Stacy

Barley is a comparatively difficult cereal to use as raw material for production of alcohol but it is quite beneficial in commercial terms due to its cost. Barley contains viscosity increasing nonstarch polysaccharides in high concentrations and processing of normal gravity mashes is complicated. Fermentation performance by yeast significantly depends on carbohydrate composition of fermented medium. In this study a laboratory experiment was conducted to ascertain the impact a method of mash saccharification has on fermentation kinetics and quality of fermented mash. Three methods of saccharification have been tested: separate hydrolysis and saccharification, simultaneous saccharification and fermentation (SSF) with one-time dosage of glucoamylase at start of fermentation and SSF with split up dosage of glucoamylase (50% of total amount added at start and the rest – after 12 hours). The kinetics of fermentation was assessed by carbon dioxide release. Glucose and maltose concentrations in mash, medium osmolality during fermentation and congeners concentration at its end were also analyzed to provide a deeper look into influence of saccharification on carbohydrates profile and yeast stress. Maximum fermentation rate was detected in samples with split up glucoamylase dosage in conditions of SSF. Glucose concentration in mash and its osmolality were lowest in these samples during fermentation compared with other methods of saccharification. These samples also showed maximum ethanol yield and minimum total congeners concentration. It is recommended to use SSF technology and split up dosage of glucoamylase during fermentation for production of alcohol from barley if water to grain ratio is 1:2.5. 

Keywords: yeast, fermentation, osmolality, glucose, maltose, ethanol

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