Recebido em 16/2/12; aceito em 11/4/12; publicado na web em 20/7/2012 CHEMICAL COMPOSITION OF SUGAR CANE SPIRITS FERMENTED BY DIFFERENT Saccharomyces cerevisiae YEAST STRAINS. The aim of this study was to evaluate the chemical composition of sugar cane spirits, fermented by different commercial Saccharomyces cerevisiae yeast strains and double distilled by pot still. Sugar cane juices were separately fermented by yeasts CA-11, Y-904, BG-1, PE-2, SA-1 and CAT-1 and distilled by pot still according to the methodology used for whisky production. The alcoholic liquids from first and second distillations were analyzed for concentrations of ethanol, volatile acidity, aldehydes, esters, furfural, higher alcohols and methanol. The sugar cane spirits derived from fermentation by the different yeast strains presented distinct chemical compositions.Keywords: yeast; cachaça; chemical composition. INTRODUÇÃOO Brasil vem se destacando na produção de cachaça, sendo a segunda bebida alcoólica mais consumida do país e a primeira entre as bebidas destiladas nacionais.1 A produção anual atinge 2 bilhões de litros, representando uma atividade econômica estimada de US$ 2,5 bilhões.2 Em relação à Legislação Brasileira (Instrução Normativa nº 13 de 29/06/2005) a denominação aguardente de cana-de-açúcar se refere à bebida com graduação alcoólica de 38 a 54% em volume, a 20 °C, obtida pela destilação do mosto fermentado do caldo de cana-de-açúcar (Saccharum officinarum), podendo ser adicionada de até 6 g L -1 de açúcares. A cachaça se refere à denominação típica e exclusiva da aguardente de cana-de-açúcar produzida no Brasil, com graduação alcoólica de 38 a 48% em volume, a 20 °C.3 Os padrões de identidade e qualidade da aguardente de cana-de-açúcar brasileira também são estabelecidos por esta legislação (Tabela 1). 3A aguardente de qualidade, isto é, aquela que apresenta composição química adequada e características sensoriais superiores, vem tendo o seu nicho de mercado, principalmente entre a população de maior poder aquisitivo, a qual procura uma bebida destilada diferenciada. O aumento do consumo de aguardente e a possibilidade de exportação exigem que o processo de fabricação seja baseado em práticas criteriosamente determinadas, para obtenção de um produto padronizado e com qualidade comprovada nos aspectos físico-químicos e sensoriais. 4,5 Como o mercado de consumo de bebidas destiladas, interno e externo, torna-se cada vez mais exigente, é importante a determinação dos compostos químicos da bebida, que estão intimamente relacionados com o aroma e o sabor do destilado. 6Diversos fatores influenciam a qualidade da cachaça, tais como a qualidade da matéria-prima, as condições de fermentação e os processos de destilação e envelhecimento. No entanto, as leveduras e as condições da fermentação são os fatores que mais afetam as qualidades química e sensorial da cachaça. A fermentação do caldo de cana pode ser considerada espontânea, pois normalmente não se utilizam cepas de leveduras selecionadas como inóculo. Desta forma, se caracter...

BackgroundApplying very high gravity (VHG) fermentation conditions to the sugarcane juice (SCJ) bioethanol industry would improve its environmental and economic sustainability without the need for major infrastructure changes or investments. It could enable a decrease in the consumption of biological and natural resources (cane/land, water and energy) while maintaining acceptable production parameters. The present study attempts to demonstrate and characterise an effective industrially relevant SCJ-VHG fermentation process.ResultsAn industry-like SCJ-VHG bioethanol production process with 30 and 35 °Bx broth was employed to investigate the effects of both the yeast strain used and nitrogen source supplementation on process yield, process productivity, biomass viability, glycerol concentration and retention-associated gene expression. Process performance was shown to be variably affected by the different process conditions investigated. Highest process efficiency, with a 17% (w/v) ethanol yield and only 0.2% (w/v) sugar remaining unfermented, was observed with the Saccharomyces cerevisiae industrial strain CAT-1 in 30 °Bx broth with urea supplementation. In addition, efficient retention of glycerol by the yeast strain was identified as a requisite for better fermentation and was consistent with a higher expression of glycerol permease STL1 and channel FPS1. Urea was shown to promote the deregulation of STL1 expression, overcoming glucose repression. The consistency between Fps1-mediated ethanol secretion and ethanol in the extracellular media reinforces previous suggestions that ethanol might exit the cell through the Fps1 channel.ConclusionsThis work brings solid evidence in favour of the utilisation of VHG conditions in SCJ fermentations, bringing it a step closer to industrial application. SCJ concentrated up to 30 °Bx maintains industrially relevant ethanol production yield and productivity, provided the broth is supplemented with a suitable nitrogen source and an appropriate industrial bioethanol-producing yeast strain is used. In addition, the work contributes to a better understanding of the VHG-SCJ process and the variable effects of process parameters on process efficiency and yeast strain response.

The objective of this was to study the chemical components from sugar cane spirits, fermented by different commercial yeast strains of Saccharomyces cerevisiae and double distilled in pot still. Sugar cane juices were fermented by the yeasts CA-11, Y-904, BG-1, PE-2, SA-1 and CAT-1 and distilled in simple still according to methodology used for Whisky production. Both distillates, from first and second distillation, was analyzed for concentrations of ethanol, volatile acidity, aldehydes, esters, furfural, higher alcohols and methanol. The sugar cane spirits came from the fermentations carried out by the different yeast strains presented different chemical compositions. The sugar cane spirits produced by the strains CA-11 and CAT-1 presented a more desirable chemical composition.

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