Effect of Antiochratoxigenic Compounds on Alcoholic Fermentation by Saccharomyces cerevisiae
Gisselle R. Apud, Diego A. Sampietro, and Pedro A.
Aredes Fernández*
*Facultad de Bioquímica, Química y Farmacia – Universidad
Nacional de Tucumán (UNT) – CONICET, Ayacucho 471, San Miguel de
Tucumán/Tucumán/4000), Argentina (pedroaredes@hotmail.com)
Ochratoxin A (OTA) is a mycotoxin with harmful effects on health. Its presence in grapes may lead to wine contamination. Aspergillus carbonarius and Aspergillus niger are considered the most dangerous sources, as they have the greatest potential for OTA production in grapes. In previous work, we demonstrated that an antifungal constituent identified as 2-hydroxy-3-(3-methyl-2-butenyl)-1,4-naphthoquinone (lapachol) combined with sodium metabisulfite completely suppressed OTA accu- mulation at concentrations of 9.8 and 156.3 µg/mL, respectively. This work evaluated fermentation by the commercial yeast Saccharomyces cerevisiae EC-1118 under vinification conditions in the presence of the mixture of lapachol and sodium metabisulfite. Alcoholic fermentation was performed in flasks with a previously pasteurized commercial white grape juice (22 Brix, pH 4.1) inoculated with S. cerevisiae EC-1118 at a concentration of 7 × 106 cells/mL (OD620nm = 0.5) and supplemented with sodium metabisulfite (156.3 µg/L) as the control medium, with or without the mixture of lapachol and sodium metabisulfite (9.8/156.3 µg/L). The flasks were corked with an air trap with sulfuric acid to avoid liquid evaporation and incubated at 22°C. Fermentation was monitored through release of CO2 by determining weight loss of the system. At the end of fermentation, yeast cells were removed and the ethanol, pH, and sugar consumption (Brix and reducing sugars) were determined in wines. The presence of lapachol and sodium metabisulfite did not affect the yeast, which achieved a complete fermentation. The resulting wines were similar in all parameters evaluated (ethanol 12%, pH = 3.8, 5.2 Brix, and 4 g/L of residual reducing sugars). We conclude that lapachol has potential use as a complement for sodium metabisulfite against OTA production by Aspergillus species without affecting fermentation.
Funding Support: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
