Abstract: This study systematically compared the in vitro digestion characteristics of microbial proteins (yeast and mycelial proteins) with those of traditional slow-digesting proteins (casein and soybean protein). Meanwhile, the differences in their digestive behaviors were analyzed via structural characterization. The results showed that the overall digestibility of the four proteins reached about 60%; while the hydrolysis degrees of yeast and mycelial proteins were higher than those of casein and soybean protein (24% and 19% vs. 14% and 12%). Structural analysis showed that yeast protein had a tight nano-spherical aggregate structure, high surface hydrophobicity and rich disulfide bond networks; while mycelial protein had a fibrillar network structure, low crystallinity and a high random coil content. These structural characteristics jointly regulated their slow and efficient digestion characteristics. This study provides a theoretical basis for the development of new protein sources with slow digestion characteristics, and holds reference value for improving the sustainable nutritional supply capacity of the emergency food system.

Key words: yeast protein; mycelial protein; structure-activity relationship; digestive properties