Техника и технология пищевых производств (Mar 2016)
THE INFLUENCE OF YEAST RACE ON THE FERMENTATION OF CHERRY PULP FOR PRODUCING DISTILLATE
Abstract
Fermentation processes are crucial in the formation of the organoleptic properties of fruit distillates. They are based on the activity of cultural yeasts of Saccharomyces type. During their metabolism in addition to ethanol, the main part of volatile components is formed representing secondary and by-products of spirit fermentation. The research object is fresh cherry fruits (Prunus subg. Cerasus) of Vladimirskaya variety and fermented cherry pulp obtained by the fermentation under anaerobic conditions at the temperature of 20±2 deg. С to the content of residual sugars not more than 3.0 g/dm3 using a variety of domestic and imported yeast races. Special attention is paid to the influence of yeast race on the glycerin accumulation, composition of organic acids and volatile components of the fermented cherry pulp. The qualitative and quantitative composition of organic acids, sugars and glycerin was studied with the use of highly effective liquid chromatography; the composition of volatile components was determined by the method of gas chromatography. It has been shown that under identical conditions, active dry yeast has a number of advantages over the traditional starter – its application promotes the reduction of pulp fermentation by 1–3 days and more complete sugar fermentation. Certain distinctions in the qualitative composition of organic acids have been established. It has been shown that the race yeast of “SIHA Aktivhefe 3” (Germany) forms the least amount of glycerin. It has been established that depending on the yeast race used various amount of methanol is accumulated in the fermented cherry pulp. Its concentration for fruit distillates is strictly regulated. The results obtained allow us to conclude that the yeast race of “SIHA Aktivhefe 3” is the most preferable for the fermentation of the cherry pulp. It provides the most complete sugar fermentation and, respectively, higher accumulation of ethyl alcohol, and promotes the accumulation of the optimum composition of valuable aromatic components.
