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ISOLATION AND SELECTION OF ETHANOL‐RESISTANT AND OSMOTOLERANT YEASTS FROM REGIONAL AGRICULTURAL SOURCES IN MEXICO
Author(s) -
ORTIZZAMORA O.,
CORTÉSGARCÍA R.,
RAMÍREZLEPE M.,
GÓMEZRODRÍGUEZ J.,
AGUILARUSCANGA M.G.
Publication year - 2009
Publication title -
journal of food process engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 45
eISSN - 1745-4530
pISSN - 0145-8876
DOI - 10.1111/j.1745-4530.2008.00244.x
Subject(s) - cane , fermentation , ethanol fuel , yeast , food science , ethanol , ethanol fermentation , bioreactor , chemistry , microbiology and biotechnology , biology , botany , sugar , biochemistry
In Mexican alcohol distilleries using sugarcane molasses, one reason for low alcoholic fermentation efficiency is the use of inferior yeast cultures. The objective of the present study was to isolate and select yeast strains from alcoholic fermentations of natural sources (sugarcane molasses, grape juice, cane juice and pineapple) from Veracruz city market and Mexican distilleries, and to evaluate their performance under laboratory conditions in an effort to select superior strains for industrial fermentations. Ethanol production, glucose composition, growth rate, “Killer” activity, ethanol and glucose tolerance of the most promising strains were monitored on synthetic and molasses media. A total of 112 yeast strains were isolated by their capacity to produce ethanol, and from these, only 58 were selected on the basis of best ethanol theoretical yields (88–96%). These strains were exposed several times to high concentrations of glucose and ethanol in order to select ethanol‐ and glucose‐tolerant yeast; 10 were obtained that adapted best to these conditions and that showed “Killer” activity. Of these strains, U3‐11, M11, JC10 and U2‐10 (obtained from grape juice, sugarcane molasses and cane juice) demonstrated the highest adaptation to both ethanol (5–7% w/v) and glucose (20% w/v). The maximum yield obtained was 0.46 g/g (90% theoretical yield) in a 20‐L bioreactor with cane molasses under nonsterile conditions.PRACTICAL APPLICATIONS The selected yeasts could be introduced into industrial processes in Mexican distilleries using sugarcane molasses in order to improve productivity and diminish contamination problems.