Fermentation of irradiated sugarcane must

Abstract

Bacillus and Lactobacillus are bacteria that usually contaminate the ethanolic fermentation by yeasts and may influence yeast viability. As microorganisms can be killed by ionizing radiation, the efficacy of gamma radiation in reducing the population of certain contaminating bacteria from sugarcane must was examined and, as a consequence, the beneficial effect of lethal doses of radiation on some parameters of yeast-based ethanolic fermentation was verified. Must from sugarcane juice was inoculated with bacteria of the genera Bacillus and Lactobacillus. The contaminated must was irradiated with 2.0, 4.0, 6.0, 8.0 and 10.0 kGy of gamma radiation. After ethanolic fermentation by the yeast (Saccharomyces cerevisiae) the total and volatile acidity produced during the process were evaluated; yeast viability and ethanol yield were also recorded. Treatments of gamma radiation reduced the population of the contaminating bacteria in the sugarcane must. The acidity produced during the fermentation decreased as the dose rate of radiation increased. Conversely, the yeast viability increased as the dose rate of radiation increased. Gamma irradiation was an efficient treatment to decontaminate the must and improved its parameters related to ethanolic fermentation, including ethanol yield, which increased 1.9%.

Viabilidade celular de Saccharomyces cerevisiae cultivada em associação com bactérias contaminantes da fermentação alcoólica

“…O uso da radiação pode ser uma alternativa de descontaminação do mosto de cana-de-açúcar. ALCARDE et al 2 demonstraram a eficiência da redução microbiológica contaminante do mosto de cana-de-açúcar por radiação gama.…”

Viabilidade celular de Saccharomyces cerevisiae cultivada em associação com bactérias contaminantes da fermentação alcoólica

“…Atualmente, as indústrias de etanol tem considerado aceitável uma população bacteriana no mosto de cerca de 10 5 UFC/mL, não sendo economicamente viável reduzir este nível (Alcarde et al, 2003). gêneros Bacillus e Lactobacillus contaminantes do mosto de cana-de-açúcar, sem ser observada qualquer alteração na capacidade fermentativa das leveduras, as quais foram acrescentadas após os tratamentos de inativação.…”

Chlorine dioxide against bacteria and yeasts from the alcoholic fermentation

“…Their high cost, need for periodic application and selection of resistant microorganisms by antibiotics are the major weak points concerning the use of these biocides. For this reason, bacterial contamination in number of 10 5 CFU/ml is an acceptable limit for alcohol operating units, not economically viable the act of reducing this level (1). So, this work aimed the evaluation of chlorine dioxide as a biocide against contaminant bacteria and yeasts from the alcoholic fermentation through the usage of minimum inhibitory concentration methodology.…”