The Study On Shelf Life Accelerated Testing Method Of UHT Milk And Application

The shelf life of UHT milk was studied with accelerated testing method by increasing storage temperature. The result showed that 37℃was optimal for shelf life accelerated test. Age gelation time of UHT milk stored at 37℃and room temperature showed significant difference (P<0.01), but the gelation time stored at 37℃and 45℃show insignificant difference , and level of proteolysis stored at 45℃was obviously lower than that stored at 37℃. the optimal accelerated temperature 37℃was used for the effect of NaCl salt addition, heat treatment and phosphate addition on shelf life, and it was found that the effect of heat treatment of milk at 55℃for 20 min(Low-temperature-inactivation treatment) after UHT delayed milk fat separation extent, reduced level of proteolysis, but shelf life determined by age gelation time was not extended. NaCl (sodium chloride) addition increased the fat separation extent and level of proteolysis. The higher the NaCl content, the severe the effect on stability of milk, and the shorter in shelf life. Addition of stabilizers (phosphate) which can enhance the stability of milk in alcohol test and oil bath test could obviously enhance the stability of UHT milk during storage, reduce the fat separation extent, reduce level of proteolysis and extend shelf life of UHT milk.