The influence of antibiotics in milk on the action of sourdough using cheese technology

Abstract

Brynza occupies an important place among cheeses in Ukraine. Brynza is a highly concentrated polydisperse system, the features of which are determined by the size of the particles of the dispersed phase. It has a white (close to white) color, uniform throughout the mass. The taste and smell of cottage cheese are sour-milk, moderately salty. Physicochemical, biochemical and microbiological processes in cheese and their intensity depend on the concentration and quality of rennet enzymes. Renal enzymes during cheese ripening inhibit the vital activity of putrefactive bacteria in cheese, while in certain concentrations they contribute to the development of lactic acid microflora of leavening preparations and their production of amino acids. Studies show that cheese contains a wide range of microflora such as Lactococcus spp., Lactobacillus spp., Leuconostoc spp., Enterococcus spp. and contaminating bacterial cells. Pasteurization of raw milk not only has a positive effect on the yield of cheese, but also protects the consumer from pathogenic microflora. Milk after pasteurization was used for the experiment. The mass fraction of fat in milk was 3.2 %, the acidity was at the level of 18.5 °T. For the experiment, 5 groups of milk samples of 100.0 cm³ each were formed. Fermentation of milk was carried out with the help of sourdough starter for cheese and rennet enzyme. The antimicrobial drug streptomycin was used to inactivate cells of yeast microorganisms and active centers of rennet enzymes. Weighed 1.0 g was dissolved in 1500 ml of distilled water. Milk with an antibiotic content of 2.0 to 4.0 U/cm3 after fermentation with sourdough and rennet enzyme had 2.6–2.9 times lower titrated acidity than in the control. A regularity was revealed that with the increase in the content of streptomycin sulfate in milk, the titrated acidity of the final product decreases. When the largest amount of antibiotic was added to milk (IV and V experimental groups of samples), the effect of leaven and enzyme preparation was not manifested, as a result of which the final product of fermentation did not differ much from fresh milk in terms of titrated acidity.