The student of Institute of food engineering and biotechnology ISTU Sokolov A.A. , Candidate of Agricultural Sciences, Associate Professor of the Department of Organic chemistry and food technology, ISTU Gusakova G.S.

Irkutsk National Research Technical University

The wort fermentation in a stationary tank with nozzles

In recent years the more widespread method is becoming the method of fermentation in conditions of high concentration of yeast immobilized on the nozzles. The first industrial tests of this method were launched in 1973 at the Moscow plant of sparkling wines. Later introduced in some large enterprises improved schemes of fermentation in treacle in a super-high concentration of yeast were developed. For small enterprises, the actual thing is the fermentation in the stationary tanks with nozzles.

The aim of this research is the intensification of the fermentation process through the use of tanks with nozzles for immobilization of yeast cells.

Objects and methods of research. The work is done with samples of juice from small-fruited local apples of the harvest of 2014 gathered in the first half of September.

The determination of juice and wine organoleptic indicators were carried out according to procedures described in [3].

The discussion of the results. The processing of apples was conducted on the technology of extracting the juice for white wines slightly oxygenated. The fruit was crushed and pressed, the resulting juice was clarified by settling for 24 hours at a temperature of 5 °C, and then was decanted from the sediment.

The total juice output was 58 dm³/kg. Table 1 shows the organoleptic characteristics of the juice obtained from the fruit of the apple-tree.

Table 1

Organoleptic indicators of juice

The name of indicator	Characteristics
Visual appearance	Transparent liquid
Color	Light straw with greenish tint
Flavor and fragrance	Of medium intensity, characteristic graded

According to organoleptic indicators, the juice received a high rating of 8.5 points. Physico-chemical parameters are given in table 2.

Table 2

Physico-chemical indicators of apple juice

The name of indicator	Norm
Mass concentration of sugar in terms of invert, g/ dm^3	12,1
Mass concentration of titratable acids in terms of malic, g/ dm^3	11,0
Extractiveness, g/ dm^3	23

On the content of sugars, the juice is suitable for the production of low-alcohol wines, but an adjustment to the acidity is required. 
For the wort preparation, the juice was normalized with water to the content of titratable acids 8 g/dm3, it reduced sugars to 8.8 %.
The fermentation was carried out on pure culture of dry wine yeast Sahccharomyces bayanus of French production by stationary method in a glass container filled with nozzles to 85 %. The temperature of fermentation was 20 оС. Dry yeast were pre-fermented and added 5 % by volume. The wort fermenting in the tank without any nozzles served as control. 
During the fermentation the temperature, the release of CO2 and the density of the wort, which was the indicator of the end of the main fermentation, were controlled. Physico-chemical characteristics of wine materials are shown in table 3. 
Table 3
Organoleptic physico-chemical indicators of wine

Indicators	Control sample	Fermentation with nozzles
Color	Golden straw	Light straw
Fragrance	Pure graded	Bright graded
Flavor	Light, fresh, harmonious, contains a low amount of alcohol, highly acid	Full, fresh, harmonious, contains a low amount of alcohol, highly acid
Alcohol content, %	4,8	5,2
Mass concentration of titratable acids, g/dm	7,9	7,8
Mass concentration of sugars, %	2,2	0,3
рН	4,1	4,1
Density	0,998	0,995
The concentration of volatile acids in %;	0,6	0,30

 
During the experiment it was observed that nozzles delay yeast cells, accelerate the release of CO2, and contribute to the acceleration of the fermentation and the wine clarification. On the 7th day the wine material in the tank with a nozzle was transparent with luster, while the control sample remained turbid even on the 15th day. Physico-chemical parameters show that sugars are fermented more fully, the accumulation of volatile acids is reduced in 2 times, which is consistent with the literature data[1,3].
Thus, during the experiment it was shown that yeast cells can absorb on nozzles, and this creates conditions which contribute to the acceleration of the fermentation process and wine clarification. 
The organoleptic evaluation of wine material increases. 
Reference list
1. Vecher A.S., Yurchenko L.A. Ciders and apple sparkling wines (chemistry and technology). Food industry. 1975. P. 135.
2. Methods of technological control in winemaking. Edited by Gerzhikova V.G. - Simferopol, "Tavrida", 2002 - 260 p.
3. Kharlamova L.N. The development of technology for obtaining wine materials using immobilized yeast providing for the biotransformation of pesticides / The dissertation of the Candidate of Engineering Sciences. Moscow, 2010.