Evolution of Microbial Load of Grapes During the Ripening Process

Abstract

In the process of growth of the grapes, as well as in the time of the alcoholic fermentation, the yeast’s structure abide many changes, that means that some kinds of yeast’s that were on the surface of the grapes can be found poorly in the first steps of the alcoholic fermentation and nearly none at the end of this process. Due to that, we decided to investigate the presence of the yeast’s during the maturation, fermentation of the grapes and also during different treatments given to the must. The research takes place at the Segarcea vineyard, on a sort of white grapes called Feteasca alba. 11 species have been found: Saccharomyces ellipsoideus, Saccharomyces oviformis, Saccharomyces rosei, Candida vini, Pichia membranaefaciens, Hansenula anomala, Kloeckera apiculata, Hanseniaspora uvarum, Metschnikowia pulcherima, Rhodotorula glutinis, Rhodotorula rubra. The smallest load of yeast’s has been found in the wine free running must, and the biggest one in the must made at the second presser. The yeast’s load depends also on the kind of wine clearance here have been used two kinds: the bentonite and sulphur dioxide and a second kind with cooling and sulphur dioxide. Due to the determination we found out that the reduction of the yeast’s emphasised by the first clarification with bentonite and sulphur dioxide. The researches will continue to analyse the influence of other clarification methods of the must on the number of yeast cells.