The secondary products of alcoholic fermentation, are compounds that appear in variablequantities in addition to alcohol and CO 2 and they are: glycerol, lactic acid, acetic acid, formic acid,substances acetoin, 2,3 butanediol, malic acid, succinic, propionic, citramalic ,dimetilgliceric. Glycerolis formed by glycero-pyruvate fermentation. Glycerol, like secondary product of the alcoholicfermentation, has the greatest importance due to its favourable influence on organoleptic properties ofwines. Its synthesis depends upon many factors. This study was conducted under laboratory conditions,using selected yeast strains from the Murfatlar vineyard, viticol Centre Medgidia, belonging to theSaccharomyces ellipsoideus, Saccharomyces italicus and Saccharomyces rosei species. The fermentationmedium was Pinot gris must which was inoculated with 1.5 to 1.7 x 10 7 cells/ ml, from the abovementioned yeasts. The objective was to establish the importance of several factors that determine wineglycerol concentration (e.g. must sugar and glycerol, concentration of inoculum, fermentationtemperature and yeast species). The glycerol produced was determined by a volumetric method withpotassium periodat. The result were: Depending of the grapevine variety and sugar content of the must,glycerol concentration of the grapes varies between 1.70 to 3.02 g/L; The inoculation rate had aninfluence on the glycerol concentration of wines; The most glycerol was formed in the first 2 to 3 days offermentation; in this period 80 to 90 g/L of the initial sugar decreased and about 2/3 of the glycerol wasformed; The most glycerol was obtained at fermentation temperatures of 20 0 C and 25 0 C; A fermentationtemperature >30 0 C leads to a decrease of glycerol formation; Yeast species and the sugar content hadthe greatest contribution to glycerol formation. Among the strains tested, SE-20, belonging toSaccharomyces ellipsoideus species was notable. This strain produced the highest glycerol concentrationin wines (6.50 to 9.80 g/L) and during fermentation did not produce foam.

glycerol, selected yeast, organoleptic proprieties

Presentation: oral