Influence of psychotrophic bacterial growth on some properties of stored raw and heat treated milks

The influence of the growth of psychrotrophic bacteria in raw, pasteurized and high heat treated milk [HHT for 96%/5 min] on some microbiological and chemical parameters during storage at 4 and 10 degree was investigated. With the exception of coliforms and staphylococci counts, all psychrotrophic groups increased during storage with a higher rate at 10 degree as compared to 4 degree. The rate of increase in proteolytic bacterial count was much higher than that of lipolytic bacteria. All chemical parameters increased during storage at 10 degree more than at 4 degree. Titratable acidity increased rapidly in raw milk than in pasteurized and HHT milks. The rate of development of NPN/TN and the free fatty acids was higher in pasteurized than in raw and HHT milks either at 4 or 10 degree. The rate of tyrosine increase in raw milk was higher than in pasteurized milk until the tenth day of storage at 4 and 10 degree, respectively; its content in HHT milk was much higher than that in raw and pasteurized milk

Ras cheese manufacture from buffaloes milk using different renneting systems

Buffalo's milk was made into cheese and served as a control [T1]. It was compared to aging of milk at 2+/- 0.1C for 24 hr with half the amount or rennet [T2] and treatment with enzyme mixture of Neutrase L + Piccantase# A before renneting [T3]. Results indicated that titratable acidity [TA], soluble protein coefficient and free amino acids were higher in T3 than the other two treatments. These results were confirmed by electrophoretic patterns. For amino acids glutamic acid as responsible for good flavour increased during ripening and was higher in T3 than in T1 and T2 while arginine which is responsible for abnormal flavor decreased during ripening. Also the total free volatile fatty acids [TFVFA] was higher in T3 than in T1 and T2 during ripening. No big differences were observed between T1 and T2 in most of the parameters measured. Organoleptically, Ras cheese manufactured from buffalo's milk treated with enzyme mixture was more preferable and therefore was recommended for manufacturing Ras cheese from buffalo's milk