ABSTRACT
Background: Cooking processes affect the physical, chemical, and structural properties of meat proteins. Cooking may also affect the protein quality of meat, as indicated by the true ileal digestibility of individual amino acids, the content of each truly digestible amino acid, and the digestible indispensable amino acid score (DIAAS). Objective: The study aimed to determine the effect of the cooking process (raw, not cooked; boiled; grilled; pan-fried; roasted) of beef on true (standardized) ileal amino acid digestibility, true ileal digestible amino acid content, and DIAAS. Methods: Beef topside steak was subjected to one of the following conditions: raw, boiled, grilled, pan-fried, or roasted, followed by mincing. The growing pig was used as an animal model for the adult human. Diets containing the raw or cooked meats (10% crude protein content) were fed to growing pigs (n = 6 per diet; mean ± SEM bodyweight, 23.6 ± 0.48 kg) and samples of terminal ileal digesta were collected under anesthesia. True ileal amino acid digestibility of the beef was determined and DIAAS values were calculated. Results: There were only minor differences in true ileal amino acid digestibility across cooking conditions with all amino acids having true ileal amino acid digestibility in the range of 90-100%. In general, boiled meat had the highest true ileal digestible amino acid content (total of 724 g/kg dry matter), and roasted meat the lowest (total of 641 g/kg dry matter; P < 0.001). The DIAAS was greater (P < 0.001) for the raw, boiled, and pan-fried meat treatments (97-99%) than for roasted meat (91%) or grilled meat (80%). The high DIAAS (range 80-99%) across cooking conditions confirms that bovine meat is a high-quality protein source. Conclusion: Cooking conditions affect the true ileal digestible amino acid content and DIAAS of beef, as determined with the use of the pig model.
