New AOCS Standardized In-vitro Protein Digestibility Methods: A Valuable Tool for Informed Food Formulation Decisions

Abstract: An understanding of overall protein digestibility of dietary protein sources is critical for establishing data in support of protein content claims on foods. In both Canada and US, data from in vivo rodent bioassay is currently required from in calculating the Protein Digestibility Corrected Amino Acid Score (PDCAAS) which is required by the respective regulatory bodies. However, given the cost and challenges of conducting animal tests, alternative ethical approaches include the use of in vitro digestibility methods that can yield data for both protein and amino acid digestibility. These methods are useful and economical techniques for generating comparative data and for product formulation purposes. A current limitation with in vitro methods, however, is the lack of standardization of existing in vitro methods. An international collaborative study was conducted to validate and standardize methods, following AOCS protocols, to measure protein digestibility using established in vitro pH-Drop and pH-Stat methods. The availability of such methods and their validation against in vivo data provide a strong argument to move away from animal testing as official methods for measuring protein digestibility. These validated protocols which are rapid and inexpensive will permit the research community to assess the multitude of factors known to impact protein and amino acid digestibility. The results of this collaborative study yielded compelling evidence that the pH-Drop and pH-Stat methods are reliable, reproducible, and scientifically valid tools for assessing protein digestibility and suitable for regulatory adoption as alternatives to in vivo testing for protein quality evaluation. The successful approval of these methods by regulatory bodies will significantly reduce reliance on animal testing and offer the food industry a reliable tool for making protein nutrient content claims, particularly for plant-based and alternative protein products.