Exploring Factors Influencing the Quality of Dietary Proteins: Implications for Food and Feed
Dr. Jim House, University of Manitoba
The provision of adequate quantities of protein and amino acids in the diets of both livestock and humans is critical for optimal growth, health and performance. As such, the quality of dietary proteins is an important consideration. Two key components that define the nutritional quality of dietary proteins, including plant-based proteins, are the respective amino acid profiles and the extent to which the protein is digested, absorbed and utilized to meet the needs of the consumer. For plant proteins in particular, numerous factors are known to influence both parameters. The amino acid composition of food and feed ingredients is influenced by the crop and varietal differences within a crop (genetic effect). Furthermore, agronomic and environmental factors, including soil type and fertility, heat units, and moisture can influence the amino acid content of important protein crops. Finally, processing of the crops, including milling strategies, thermal and non-thermal processing steps can influence the content of amino acids. The same factors can also influence the overall digestibility/availability of the amino acids. Novel strategies, including the use of new spectroscopic methods, are available to assess the impact of the above factors on the amino acid content of crops. The latter can replace expensive and time-consuming traditional wet chemistry methods for amino acid analysis and offer new tools for plant breeders and nutritionists to assess the quality of dietary proteins. Additionally, new in vitro methods have been standardized to assess protein and amino acid digestibility and provide additional tools for nutritionists for protein characterization. The availability of these tools will assist in ensuring that we can continue to provide high quality protein sources for both livestock and human diets.
Keywords: protein quality, amino acids, digestibility, variability.