Cheddar Cheese 숙성과정에 있어서 Casein 의 변화 = Degradation of Caseins during the Ripening of Cheddar Cheese

다국어 초록 (Multilingual Abstract)

To study the change of cheese casein components during the ripening of cheddar cheese, the fresh cheese was ripened for 6 monthes at 10±2℃, 90±5% of relative humidity(R.H), water soluble nitrogen and noneprotein nitrogen(N.P.N), polyacrylamide gel-electrophoretic patterns, DEAF-cellulose chromatographic fractions, sephadex gel-filtration, and the content of free amino acids, were studied during the ripening of the cheese at the Laboratory of Dairy Chemistry, Livestock Experiment Station in Suwon, Korea. The results obtained were as follows: (1) Water soluble nitrogen was 28%, 39%j and 59% of total nitrogen and N.P.N. was 9% 17%, and 22% of total nitrogen at 4th week, 12th week and 24th week of chose ripening, respectively. (2) On 6% polyacrylamide gel containing 8M urea and β-mercaptoethanol, electrophoporetic patterns of cheese casein, evidenced 3, 9, 12 bands at the initial, 4th week and 12th week of cheese ripening, respectively. The casein in the cheese aged for 4 weeks was separated into 3 bands, such as α_(s1)-casein, α_(s1)-1-casein. and α_(s1)-2-casein, in the α_(s1)-casein area. The cheese casein aged for 12 weeks evidenced only 2 bands, such as α_(s1)-2-casein and α_(s1)-3-casein with the disappearence of α_(s1)-casein and α_(s1)-1-casein in the α_(s1)-area, and was separated into 4 bands, such as β-casein, β-1-casein, β-2-casein and β-3-casein in the β-casein area. A number of minor bands appeared in the lower descending mobility area than β-casein. It would mean that α_(s1)-casein was degraded earlier than β-casein in cheese ripening. (3) Aged cheese casein in the DEAE-cellulose column(2.5×40㎝) with 0.02M Phospate buffer and 0.3-N. NaCl in 0.02M phosphate buffer, was separated into 4, 8 and 11 protein peaks at the initial, 4th week and 8th week of cheese aging, respectively. (4) The casein of 12 weeks old cheese was separated better and was diffused wider in sephadex G-50 than in sephader G-200, and fresh cheese was separated better and the diffusion was wider in sephadex G-200 than in sephadex G-50. The cheese casein probably were degraded into smaller proteins by rennet and other proteases from lactic bacteria during cheese fermentation. (5) In the cheese aged for 12 weeks many free amino acids appeared, and a number of unknown peaks were found, such as X₁, X₂ and X₃.