Protein quality has relied on methods such as PDCAAS. However, the Food and Agriculture Organization has proposed a new method called DIAAS to better assess protein quality in human foods using the pig as a model. This shift is crucial, not only for optimizing diets, but also for understanding the nutritional value of protein-rich foods. According to the DIAAS method, protein claims can only be made for foods with a score above 75. In general, animal-based foods are considered high quality proteins with score above 75 or 100, being, in most cases, complete proteins that can complement lower quality proteins such as plant-based proteins. Meats, eggs, and fish are examples of high quality proteins, however, salmon proteins are also available, and use of by-products in human consumption has been increasing due to their nutritional value and versatility. Novel sources of salmon proteins such as salmon hydrolysate that may be used in human nutrition have been developed. Salmon hydrolysate proteins contain more than 68% crude protein (CP) and are highly digestible food ingredients, but limited information demonstrating the protein quality of these products is available. Therefore, the objectives of this study were to determine the standardized ileal digestibility (SID) of amino acids (AA) and the digestible indispensable amino acid score (DIAAS) for salmon proteins when fed to growing pigs.

Hodgkinson, Suzanne M., Natascha Stroebinger, Nikkie van der Wielen, Marco Mensink, Carlos Montoya, Wouter H. Hendriks, Sonja de Vries, Hans H. Stein, and Paul J. Moughan. 2022. Comparison of True Ileal Amino Acid Digestibility between Adult Humans and Growing Pigs. J. Nutr. 2022;152:1635–1646. doi.org/10.1093/jn/nxac077.

In the U.S. and most other developed countries, animal-based proteins provide a significant portion of the human diet. However, predictions for animal protein consumption indicates that consumption in Europe and North America will begin to decline by 2035 because plant-based proteins have become accepted as having an appearance, texture, and taste that is close to that of animal products. Examples of plant based proteins that are already on the market are plant-based burgers such as the Impossible Burger and the Beyond Burger, which are produced primarily from soy and pea protein, respectively. The digestible indispensable amino acid score (DIAAS) is recommended by FAO as the best method to determine protein quality in human foods. This method allows for calculation of the protein value of both individual ingredients and combined meals consisting of several proteins. Previous research in our laboratory demonstrated that values for DIAAS obtained in milk and breakfast cereals are additive in mixed meals, and the principle of additivity is believed to be applicable to all types of combined meals, but additional research to demonstrate this is needed. Therefore, the objectives of this experiment were to determine DIAAS values for animal and plant-based burgers and test the hypothesis that DIAAS calculated for a burger and a burger bun are additive in a combined meal.

Bailey, Hannah M., John K. Mathai, Eric P. Berg, and Hans H. Stein. 2020. Most meat products have digestible indispensable amino acid scores that are greater than 100, but processing may increase or reduce protein quality. British Journal of Nutrition (2020), 124, 14–22. doi:10.1017/S0007114520000641. Link to full text.