Abstract
Medium chain fatty acids (MCFA) and long chain unsaturated fatty acids (LCUFA) have been studied in the process of alcoholic wine fermentation. The first being toxic for the yeast cells, and the second being necessary for their survival. In this work, the contents of MCFA and LCUFA, during alcoholic fermentation of Carménère were studied in nineteen fermentations under selected temperature and aeration conditions, at laboratory scale using Saccharomyces cerevisiae yeast. Several standard fermentation variables related to fatty acids were monitored daily with samples collected every 24 hours. These samples were analyzed by a gas chromatograph with flame detector. Comparing the results, with contents under normal operating conditions (Temperature of 28 °C, pH of 3.5, aeration at the beginning of fermentation); lower concentrations of MCFA and LCUFA, at 24 °C and 32 °C were observed. Although, concentrations of the fatty acids increased at the same stage of the fermentation, they never exceeded the production levels observed under normal fermentation.
In addition, MCFA/LCUFA ratio at 32 °C was between 3.55 to 4.43, due to significant increasing of MCFA production at this temperature, therefore, according our results is suggested work below 28 ºC.
On the other hand, under anaerobic conditions, the MCFA/LCUFA ratio was very high compared to the other aeration strategies, supporting that the oxygen improve the fermentation performance, avoiding the high production of MCFA, which can be one of the causes of stuck and sluggish fermentations. Also, using aeration at the beginning and at the end of exponential phase, the MCFA/LCUFA ratio was usually less than 1, indicating a greater production of LCUFA, when the oxygen is used during the fermentation.
- Received March 2018.
- Revision received April 2018.
- Revision received September 2018.
- Revision received December 2018.
- Accepted December 2018.
- Published online January 2019
- ©2019 by the American Society for Enology and Viticulture
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