The study examined the impact of oxidation with performic acid on the true ileal amino acid digestibility (TIAAD) of seven dietary protein sources. TIAAD of both the unoxidized and oxidized protein sources was determined in the growing rat and compared. After oxidation, TIAAD was 30 and 58% higher across amino acids (P < 0.001) for the more poorly digestible protein sources, zein and blood meal respectively, 6-16% lower (P < 0.05) for the more highly digestible protein sources (casein, soy protein isolate, and beef muscle protein), and generally unchanged (<2% difference) for the more moderately digested protein sources (lactalbumin and gelatin). Overall, the change in TIAAD after oxidation was negatively correlated (P < 0.001, r = -0.90) with the TIAAD prior to oxidation, most likely as a result of the balance between two processes, protein denaturation resulting in increased digestion and indigestible limit peptide formation resulting in decreased digestion.
Keywords: digestibility; ileal; oxidation; performic acid; protein.