Determination of lysine damage and calculation of lysine bio-availability in several processed foods.

By analyzing lysine and furosine the amount of inactivated lysine in several food systems was determined and the values for available lysine and total lysine were calculated. Considerable heat damage was found in heated cereal products, and in heated milk products, including several formula for children and hospitalized patients. Some products contained more inactivated lysine than available lysine. This may have consequences for the nutrition in low protein consuming populations and leads to errors in predicting the protein quality, e.g., by the recently proposed "Protein Digestibility Corrected Amino Acid Score".