Fermentation of sweet sorghum grains for beer production using a traditional yeast inoculum
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Date
2018
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Punjab Agricultural University, Ludhiana
Abstract
Beer is the most popular drink among alcoholic beverages with certain medicinal values and sorghum is one of the promising substrate for its production. In the present study, SSV-84 variety of sweet sorghum was evaluated for its beer production potential. Two yeasts viz. P1 and P2 were isolated from phaff, indigenous inoculum of North Western Himalayas and were further characterized on the basis of morphological and biochemical characteristics and were identified by ITS region sequencing as Cyberlindnera fabianii and Clavispora lusitaniae, respectively. Sc01 (KC515355) and MTCC-11815 were used as reference strains in this study. Growth kinetics studies depicted that Sc01 and P1 showed a continuous increase at OD600nm till 36 hrs. 11815 and P1 were at par for their alcohol production ability and were found to produce highest alcohol content i.e. 8.3 % (v/v) and 8.1% (v/v), respectively. Alcohol tolerance was found out to be highest i.e. 10.7 % (v/v) in case of 11815, and the lowest was at par in case of Sc01 and P2 i.e. 9.2 % (v/v) and 9.0 % (v/v), respectively. The yeast isolates used in the study were found out to be medium flocculators. The fermentation efficiency of the yeast isolates was in the range of 48-85 %. Three yeast isolates viz. 11815, P2 and Sc01 were further used for beer production. Optimum temperature was found out to be 28-30˚C and maximum alcohol was produced on 7th day of fermentation by yeast strain Sc01 (4.4% v/v) with sweet sorghum wort, 11815 produced 3.9% v/v alcohol and P2 produced 3.2% v/v alcohol. Titrable acidity of the beer produced was in the range of 0.123-0.254 %, the pH ranged between 3.2-3.6 and color of all the beer samples was light yellow. Beer produced by using Sc01 strain having 40:60 ratio of sweet sorghum: pilsner malt was considered the best on the basis of sensory evaluation followed by P2. The results of the study infer that Sc01 and P2 can be used for scale up of beer at pilot scale.
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