UDC 637.142.2

GNITSEVYCH Victoria, 
Doctor of Technical Sciences, Professor of Kyiv National University of Trade and Economics

CHYKUN Nadiya,
Senior teacher of Kyiv National University of Trade and Economics

HONCHAR Yuliia,
Postgraduate student of Kyiv National University of Trade and Economics 

KINETICS OF FERMENTATIONOF LACTOSE WHEY 

Background. Production volumes of whey and all kinds of raw material sources in Ukraine constitute about 200 tons per yearnow. In the European Union each year milk industry produces 75 million tons of whey, about 40 % of the amount of whey is utilized. One promising direction that extends the use of whey is getting low-lactose products resulting from the use of enzymes of directed action, including based on propionic acid bacteria of the genus Propionibacterium freudenreichii subspecies shermanii.
The aim of the study is to research of the effect of the temperature, pH environment, concentration of the added ferment and the time on the lactose content in the milk whey.
Material and methods. The content of lactose was determined by refractometric method [14]. Repetition of experiments and analyzes is threefold.
Results. The influence of temperature, pH of the medium, concentration of the introduced enzyme preparation on the change of lactose content in milk whey was studied. To construct a trend for the development of fermentative hydrolysis of lactose in milk whey, measurement of the results was carried out at regular intervals of 22 hours. The recommendations for the cultivation of bacteria of the genus Propionibacterium freudenreichii subspecies shermanii were summarized, and the boundary conditions of the enzyme activity on their basis were determined. According to the recommended concentrations of the enzyme preparation in the investigated milk whey, temperature regimen, pH value of the medium and the presence of activators, rational technological regimes of fermentolysis have been substantiated.
Conclusion. It was found that at t = 50 ^оС, pH 5–5.5, the presence of 2 % CaCO₃ solution, themass fraction of lactose decreases from 5.7 to 2–2.2 %. and achievement of maximum effect for the chosen technological parameters occurs after 12 hours. The obtained data will be used to optimize the lactose fermentolysis process.

Keywords: cheese whey, temperature, pH, enzyme, fermentolysis, lactose.

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