Influence of the quality of raw milk on microbiological quality of butter

This paper presents the results of research on impact of quality of the starting raw material, raw milk, as well as intermediate products in the technological process of preparation, on the quality and microbiological quality of butter. In order to perform quality assessment of technological suitability of raw milk for butter production investigation the chemical composition and physical properties of raw milk was carried out. In addition, the physical and chemical analysis of raw sour cream, pasteurized sour cream, butter churning at certain stages, buttermilk as a byproduct and finished packaged butter has been done. Microbiological safety of raw milk was performed in compliance with the Regulation on the quality of raw milk (Sl. glasnik RS, nr. 21/2009), while the assessment of safety parameters (analysis of finished products - butter), and the hygiene of its production process (analysis intermediate products, by-products and finished products) was performed in accordance with the Rules of general and special conditions of food hygiene at any stage of production, processing and trade (Sl. glasnik RS, nr. 72/2010). Results of microbiological analysis showed that the quality of raw milk at the reception of milk was not on a satisfactory level. The total number of aerobic mesophilic bacteria, of the bulk sample of milk from silos, ranging from 8x10**5 to 2.8 x 10**6 ml, indicates the elements of poor hygiene during milking, as well as during other manipulations with raw milk (decanting, storage in refrigerator, transportation, receipt and storage in silos). The high initial contamination of raw milk influenced the presence of a relatively large number of mesophyll (5.2 x 10**$/ ml) and sporulated bacteria in raw sour cream (10/ml) after its separation and storing in the receiving tanks. After heat treatment of sour cream, at 95-193 deg C for 5 minutes, a complete reduction termoresistant and a drastic reduction of mesophilic bacteria took place. The examined samples showed that the product is safe and that hygiene of the process is satisfactory at different stages of butter churning and production. The results of this research indicate that special attention should be paid to the microbiological safety and quality of raw material during the butter production process, and to the fulfillment of hygienic and sanitary conditions during the production cycle (washing and disinfection of equipment, temperature pasteurization regimes etc.).