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Factors Affecting Zymomonas mobilis subsp. francensis Growth and Acetaldehyde Production
Author(s) -
Coton M.,
Laplace J.M.,
Guichard H.,
Coton E.
Publication year - 2008
Publication title -
journal of the institute of brewing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.523
H-Index - 51
eISSN - 2050-0416
pISSN - 0046-9750
DOI - 10.1002/j.2050-0416.2008.tb00315.x
Subject(s) - acetaldehyde , zymomonas mobilis , chemistry , food science , yeast , ethanol , yeast extract , nitrogen , ethanol fuel , food spoilage , fermentation , biochemistry , biology , bacteria , organic chemistry , genetics
ABSTRACT: An experimental plan was designed to determine the incidence of factors encountered during cider production on Zymomonas mobilis subsp. francensis growth and acetaldehyde production. Different factor combinations of pH (3.50 to 4.10), SO 2 addition (0, 50, 100 and 200 mg/L), nitrogen source concentrations (0.5 and 5.0 g/L), polyphenol cider marc extract supplementation (0.25 and 1.00 g/L), temperature (12°C, 18.5°C and 25°C) and inoculation level (10 2 and 10 5 CFU/mL) were tested over a 30‐day period at regular time intervals in synthetic medium with ethanol. Viable cell counts and acetaldehyde production were correlated. Individually, and in decreasing significance, the following factors influenced acetaldehyde production: nitrogen source, SO 2 addition, inoculation level, temperature and pH. On the other hand, presence of polyphenol cider marc extract was not significant. A model was determined based on factor interactions. At high contamination levels (10 5 CFU/mL), conditions leading to a high risk for spoilage were observed at pH values ranging from 3.75 to 4.10, at 0 to 50 mg/L total SO 2 and in the presence of 5 g/L nitrogen source (yeast extract) while temperature did not in fact appear to play a key role. At lower contamination levels (10 2 CFU/mL), the risk was drastically reduced. The only conditions leading to increased acetaldehyde levels were a high pH 4.1, no added SO 2 and high nitrogen source concentration (5 g/L yeast extract).