Abstract
Abstract This exploratory work aims to identify the potential inhibitors of lactic bacterial growth and to propose enological practices to guarantee the occurrence of spontaneous malolactic fermentation (MLF) in wines from traditional and double-pruning management harvests in southeast Brazil. One white wine from a summer harvest and one red wine from a winter harvest that failed to complete MLF were utilized as comparative models to identify inhibitor compounds to lactic bacteria. Wine composition, alcoholic-fermentation temperature and bacterial strain contribute to the success or failure of MLF. Temperatures below 12 °C during alcoholic fermentation decrease lactic bacterial metabolism and may impair the bacteria’s growth after yeast cells lysis. A must pH below 3.2 in a summer harvest impairs bacterial growth, and the association of low pH with a free-SO2 concentration above 10 mg L-1 may inhibit MLF. For grapes with a high sugar content, harvested in the winter cycle, enologists should keep the alcohol content below 15% and control the alcoholic-fermentation temperature.
Highlights
Malolactic fermentation plays an important role in reducing acidity and improving both the microbiological stability and the aroma profile of wines
The conditions required for the induction and appropriate course of malolactic fermentation (MLF) include initial temperatures of 20 °C to 25 °C, a free-SO2 content below 10 mg L-1, a total SO2 concentration below 30 mg L-1, a pH level between the range of 3.2 and 3.4, and nutrients, which are obtained from the sediment of yeast cells (Lasik, 2013)
This initial exploratory work aims to identify the potential inhibitors of native lactic bacteria in traditional vinification and winter wines, and to suggest enological practices to ensure the occurrence of faster MLF
Summary
Malolactic fermentation plays an important role in reducing acidity and improving both the microbiological stability and the aroma profile of wines. Grapes from a winter harvest have higher levels of malic acid than those harvested in the summer (Mota et al, 2010), and MLF is an essential practice to guarantee the quality of the wine. As far as the authors know, there are no studies regarding the behavior of native strains of lactic bacteria from the vineyards of southeast Brazil. This initial exploratory work aims to identify the potential inhibitors of native lactic bacteria in traditional vinification (summer harvests) and winter wines (double-pruning management), and to suggest enological practices to ensure the occurrence of faster MLF. Received 06 June, 2017 Accepted 09 Sept., 2017 1 Núcleo Tecnológico EPAMIG Uva e Vinho, Caldas, MG, Brazil 2 Departamento de Agronomia, Universidade Federal dos Vales do Jequitinhonha e Mucuri – UFVJM, Diamantina, MG, Brazil 3 Departamento de Alimentos e Nutrição Experimental, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo – USP, São Paulo, SP, Brazil 4 Departamento de Ciência dos Alimentos, Universidade Federal de Lavras – UFLA, Lavras, MG, Brazil
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