Search

The aim of this work was to examine the reduction in antigenicity of milk proteins in powdered milk by gamma irradiation which is increasingly used for food safety. Skim milk powder samples were exposed to irradiation doses of 1, 5, and 10 kGy. A greater reduction of -casein and -casein was found than -casein and -casein by capillary electrophoresis. Competitive indirect ELISA and passive cutaneous anaphylaxis tests using guinea pigs showed a reduction in antigenicity of powdered milk by 10kGy gamma irradiation. These results indicated that gamma irradiation reduce allergenicity of milk proteins by structural changes of -casein and -casein, and can be useful for dairy products.

The lactase activities of nine species of lactic acid bacteria were compared using the chromogenic substrate, . Streptococcus thermophilus KACC 91147 had the highest lactase activity among a total of thirty strains of Lactobacillus and S. thermophilus tested, including commercial strains. S. thermophilus KACC 91147 released of galactose in treated milk A () and in treated milk B ( milk) over 2 hours. In milk tolerance tests, the blood glucose level (BGL) of 6 volunteers (2 males and 4 females) clinically diagnosed as lactose intolerant increased 3.0 mg/dl after drinking milk A, but a significant (p was found after drinking milk B. This result suggests that the addition of S. thermophilus KACC 91147 cells into milk aids the digestion of lactose in milk and ameliorates the symptoms of lactose-intolerant individuals due to the activity of lactase from the lactic streptococci.