Bulgarian Journal of Agricultural Science, 15 (No 6) 2009, 494-500 Agricultural Academy EFFECT OF GAMMA STERILIZATION ON THE FATTY ACID PROFILE OF LYOPHILIZED BUFFALO CHEESE S. IVANOVA, I. NACHEVA, D. MITEVA, K. LOGINOVSCA and Ts. TSVETKOV Institute of Cryobiology and Food Technologies, BG -1407 Sofia, Bulgaria Abstract IVANOVA, S., I. NACHEVA, D. MITEVA, K. LOGINOVSCA and Ts. TSVETKOV, 2009. Effect of gamma sterilization on the fatty acid profile of lyophilized buffalo cheese. Bulg. J. Agric. Sci., 15: 494-500 The changes in the fatty acid profile of buffalo cheese after lyophilization and gamma rays treatment at 2 kGy and 4 kGy doses have been studied with the objective of its shelf-live prolongation. The results of the experiments show a decrease of the content of the saturated fatty acids after irradiation at the aforesaid gamma rays doses. A favorable effect on human organism has the decrease of the quantity of the short-chain fatty acids – by 13.16 % on irradiation at 2 kGy and by 18.73% on irradiation at 4 kGy, compared to the control sample. A satisfactory correlation between the essential fatty acids omega-6/omega3 has been observed in the lyophilized buffalo cheese. In the process of irradiation this balanced correlation changes and increases up to 7.32 and 8.31 at 2 kGy and 4 kGy respectively. Key words : buffalo cheese, fatty acid profile, fatty acids, lyophilization, gamma sterilization e-mail: iliana_nacheva@abv.bg Introduction Cheese is a valued food that was known yet by the ancient peoples and nowadays still enriches and varies our table. Cheese is a traditional product in Bulgarian cuisine with high nutritional value and physi- ological sufficiency which are determined by the high content of proteins and fats, by the presence of well assimilable by the human organism peptides and free amino acids, vitamins and microelements. It is obtained as a result of the inoculation or curdling of the milk, cutting of the whey, adding of salt and a process of lactic acid fermentation. During ripening its proteins undergo qualitative changes and become more easily digestible and better assimilable by the organism. Cheese has an important complementing function in the normal rational nutrition which is not always provided with wholesome proteins of animal origin as well as with sufficient calcium salts. One of the impor- tant characteristics of the quality of dairy products is the determining of the fatty acid profile. In the pro- cess of the cheese ripening changes in the quantity of fatty acids take place (Dimitrov et al., 2008). Mihailova et al. (2003) and Mihailova et al. (2004) have established a decrease of the quantity of the satu- rated fatty acids in the process of cheese production and have noted an increase during the ripening pro- cess. According to Prandini et al. (2001), the micro- organisms in milk and the rennet (starter) used for producing of dairy products have an effect on the fatty 494