ISHS Acta Horticulturae 640: XXVI International Horticultural Congress: Viticulture - Living with Limitations
INFLUENCE OF FERMENTATION CONDITIONS AND YEAST SPECIES ON THE GLYCEROL CONCENTRATION OF WINES |
| Authors: | G. Beleniuc, G. Marin, A. Ranca |
| Keywords: | Inoculated density, prefermentation period, alcohol, total acidity, volatile acidity |
| Abstract:
Among the secondary product of alcoholic fermentation, glycerol has the greatest importance due to its favorable influence on organoleptic properties of wines. Its synthesis depends upon many factors. This study was conducted under laboratory conditions, using selected yeast strains from the Murfatlar Research Station yeast collection, belonging to the Saccharomyces ellipsoideus, S. bayanus and S. italicus species. The fermentation medium was Pinot gris must which was inoculated with 1.5 to 1.7 x 107 cells/ ml. The objective was to enumerate the importance of several factors that determine wine glycerol concentration (e.g. must sugar and glycerol, concentration of inoculum, fermentation temperature and yeast species). The glycerol produced was determined by volumetric method with potassium periodat. Depending on the grapevine variety and sugar content of the must, glycerol concentration of the grapes varied between 1.70 to 3.02 g/L. The inoculation rate had no influence on the glycerol concentration of wines. Most of the glycerol was formed in the first 2 to 3 days of fermentation during which sugars decreased by 80 to 90 g/L and about 2/3 of the glycerol was formed. Glycerol formation was greatest at fermentation temperatures of 20ºC and 25ºC. A fermentation temperature >30ºC led to a decrease of glycerol formation. Yeast species and the sugar content had the greatest contribution to glycerol formation. Among the strains tested, SE-2, of the species Saccharomyces ellipsoideus, produced the highest glycerol concentration in wines (7.80 to 9.20 g/L) and did not produce foam during fermentation. | |
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