Protein Quality Evaluation of Animal Food Proteins by <i>In-Vitro</i> Methodologies

Abstract

Animal protein foods are undoubtedly among the most concentrated source of essential amino acids (AA) for the human diet. However, their high prices and diseases associated to their excessive consumption have fomented the consumption of other alternative sources of animal proteins such as those from marine or aquatic species. Sonora is a well recognized producer of animal foods in Mexico, both terrestrial and aquatic. In this study, the protein quality evaluation of these animal food sources, highly produced and consumed in Sonora , is proposed, using in-vitro methodologies. Four differ ent species, from each aquatic and terrestrial origin, were selected. Samples of lean muscle were used in all cases. Various i n-vitro methodologies for protein quality evaluation were selected, alternatives to the animal bioassays: % digestibility, Total amino acid analyses (HPLC), PDCAAS, computerized PER calculations (C-PER and DC-PER) and total collagen contents. % in-vitro digestibility presented significant differences among samples from terrestrial species, but muscle from aquatic species did not showed significant differences. All sources of proteins, both aquatic and terres trial proved to be rich sources of essential amino acids. PDCAAS was unable to establish significant differences in pro tein quality among sources of protein from different origin. Both methods C-PER and DC-PER were more exact in their results and were able to detect significant differences among samples of different origin. An important finding was the great difference in the total collagen content between aquatic and terrestrial sources of proteins, where terrestrial muscle proteins had almost 10-time more collagen than aquatic protein sources. However, these collagen contents did not seem to have a significant influence in the protein quality of these animal proteins. These muscle proteins, from both aquatic and terrestrial species, confirmed to have a high protein quality and some of the in-vitro methodologies used in this study represent a valuable alternative to the animal bioassays.