Yeasts from Local Sources: An Alternative to the Conventional Brewer’s Yeast

Author Umeh, S.O.
Co-Author Agwuna, L.C., Okafor, U.C.
DOI

Country : Nigeria
Subject : Applied Microbiology and Brewing

Keywords : Palm wine, Burukutu, Brewing industry, Beverages, Saccharomyces cerevisiae

Abstract

Saccharomyces cerevisiae is common yeast of economic importance in food and brewing industries. They are obtained commercially from foreign suppliers and are costly. Their high cost also renders the cost of their products too high for consumers. Yeast strains were isolated from local beverages (Burukutu and Palm Wine) and identified as Saccharomyces cerevisiae. The isolates (SPW from palm wine and SBB from burukutu) were characterized for certain attributes necessary for beer production and compared with the commercial brewer’s yeast (SCT). The attributes important for beer production investigated include; ethanol production, ethanol tolerance, growth at elevated temperatures, ability to ferment simple sugars, flocculation ability, resistance to different stress conditions and inability to produce hydrogen sulfide. Results showed that none of the three isolates produced hydrogen sulfide gas, ferment raffinose and lactose, while they all ferment glucose, maltose, fructose, sucrose and galactose. Flocculence assay showed that all the isolates flocculated and tolerated 15% (v/v) ethanol with different degree of growth as intensive, moderate and low for SPW, SBB and SCT respectively. All the isolates grew well at 37oC but at 45oC the growths were moderate and low for SPW and SBB respectively while SCT had no growth. They all survived at different stress conditions for temperature and cell osmotic pressure in high concentration of ethanol and sugar. These results showed that Saccharomyces cerevisiae isolated from local sources can be applied in beer production. This will reduce immensely the high cost of beer which can be attributed to the cost of imported brewer’s yeast.

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