Effect of storage temperature and Maillard reaction on interactions between sterilized goat milk proteins

The effect of storage temperatures (5, 30 and 45) ˚C on nitrogen distribution and interaction of casein and whey proteins with MFGM proteins in sterilized goat milk was studied. pH of sterilized goat milk samples with and without lactose were 7.32 and 8.76 respectively, directly after sterilization. During storage at 5˚C for 8 weeks the pH of sample with lactose increased to 7.44, while the pH of sample without lactose decreased to 7.34. At 30˚C the pH of sterilized goat milk samples with and without lactose decreased to 6.3 and 6.74, respectively while these values decreased to 6.30 and 8 respectively in samples stored at 45˚C. NCN ratio was decreased gradually with the increment of storage time for samples with and without lactose stored at 5 and 30˚C, and for sample without lactose stored at 45˚C. For sterilized goat milk sample with lactose stored at 45˚C, there was a high increase in NCN to 47.5% after 4 weeks of storage and this ratio remained constant until the end of the experiment. High-molecular-weight bands appeared in SDS-PAGE in the samples with and without lactose but the intensity of these bands indicates that the formation of large protein aggregates were greater in higher storage temperatures and in the presence of lactose.

کلیدواژه ها:

Storage temperature ، Maillard reaction ، Sterilized goat Milk proteins