Influencia da temperatura e infecção latica na fermentação alcoolica

AUTOR(ES)
DATA DE PUBLICAÇÃO

1989

RESUMO

The goal of this work is to study the influence of temperature and infection of lactic acid bacteria on alcoholic yield and viability of two strains of two Saccharomyces cerevisiae (NRRL and FTPT 0472) growing on cane sugar broth at pH 4,5 supplemented with N and P. The incubation was carried on a temperature gradient incubator between 28 and 40ºC. Determination of yeast concentration (plate count and microscopy), bacterial concentration (plate county CO2 (gravimetry), dry cell mass (gravimetry), pH (potenciometry), sugar concentration (colorimetry) and ethanol (gas chromatography) was done in the initial and final samples. The optimum temperature for ethanol product ion was found to be 38 °C for strain NRRL Y-2342 and 34 ºC for strain FTPT 0472. The maximum alcoholic yield coefficient obtained was the- same for bath strains (Yp/s = 0,47). However the productivity was slightly higher (11%) for the strain NRRL Y-2342. The reproduction of yeasts was adversely affected above 40ºC but was enhanced at 1ower temperatures (28 to 32 °C) .There was a decrease in the alcoholic, yield of 5% in the presence of Leaconostoc and an increase of 6% in the presence of Lactobacillus. The productivity obtained with contaminated cultures was higher, with the exception of some experiments contaminated with Lactobacillus. Both bacterial contaminants affected adversely the budding of strain NRRL Y-2342 but did not affect the budding of strain FTPT 0472. At the end of fermentation the level of the Lactobacillus contamination remained constant, whereas viable cells of Leaconostoc could not be detected. This was due to the sensitivity of Leaconostoc against the ethanol produced during the alcoholic fermentation, and the growth characteristics of Leaconostoc in the medium tested.

ASSUNTO(S)

fermentação saccharomyces alccol

ACESSO AO ARTIGO

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