Evaluating quality of novel alternative protein sources (microbial and insect proteins) using the INFOGEST in vitro digestion model

Sustainable alternative protein sources are needed for humans and animals, but their quality, including digestibility and Indispensable Amino Acid (IAA) contents, need to be determined. We evaluated the protein quality of novel microbial (MPX) and insect (BSFL) proteins, in comparison with more conventional, Fishmeal (FM) and Pea Protein (PP), using the INFOGEST model. MPX was highly digestible (92.6 %) and similar to PP (99.3 %), but higher than both FM (82.4 %) and BSFL (72.9 %, p < 0.001). The use of 6.25 as conversion factor for N, overestimated the protein content of MPX and BSFL, due to their high non-protein N contents, impacting the measure of quality. Digestible IAA Ratios for MPX and BSFL were underestimated when crude protein was used, but use of total AA resulted in similar Digestible IAA Scores for MPX (0.96) and FM (0.95), with PP (0.72) and BSFL (0.51) being lower (P < 0.001). MPX is the better quality novel protein source.