Abstract
The effects of the sampling method on the estimation of lysine contents in food proteins was studied using polished rice, white barley, sweet potato, soybean, spinach, garland chrysanthemum (Chrysanthemum coronarium), lean beef, pork loin, and horse mackerel (Trachurus symmetricus). All the sample prepared by acetone-dehydration and non-heating process showed the highest lysine contents both by microbial and DNP method, and the ratios of the DNP-estimates to the microbial ones were 90 to 95% in vegetable foods and 95 to 97% in animal foods; while heating the samples at 50°C for 15 hours or at 98°C for 1 to 8 hours decreased the ratios to 91 to 83% in both vegetable and animal foods. Biologicallyactive lysine seems to be necessarily estimated using non-heated or acetone-dehydrated samples
