Irradiation effect on α- and β-caseins of milk and Queso Blanco cheese determined by capillary electrophoresis

摘要

Milk and Queso Blanco cheese were exposed to irradiation with doses of 1, 2, 3, 5, and 10kGy to investigate the irradiation effect on α- and β-casein using a capillary electrophoresis. α_(S1)-Casein to total protein ratio in raw milk was decreased from 19.63% to 8.64% by 10 kGy of gamma irradiation. The ratio of α_(S1)- to α_(S0)-casein was also decreased from 1.38 to 0.53, which showed α_(S1)-casein is more susceptible to gamma irradiation than α_(S0)-casein. Similarly, α_(S1)-casein to total protein ratio in Queso Blanco cheese was decreased from 17.48% to 7.82% and the ratio of α_(S1)- to α_(S0)-casein was decreased from 1.16 to 0.43 by 10 kGy of gamma irradiation. Dose-dependent reduction of β_(A1)-casein was also found. β_(A1)-Casein to total protein ratios in raw milk and Queso Blanco cheese were decreased from 22.00% to 14.16% and from 21.96% to 13.89% after 10 kGy, respectively. The ratios of β_(A1)- to β_(A2)-casein were from 1.10 to 0.64 and 0.93 to 0.57 in milk and Queso Blanco cheese, respectively. However, α_(S0)-, β_B-, β_(A3)-casein increased by irradiation at 10 kGy. The results suggest that α_(S1)-casein and β_(A1)-casein were more susceptible to gamma irradiation, and may be related to the reduction of milk allergenicity caused by gamma irradiation.