Peptidomics insights into the interplay between the pre-digestion effect of mixed starters and the digestive pattern of sausage proteins.

This work investigated the influence of mixed starters (Lactobacillus plantarum CD101 and Staphylococcus simulans NJ201) on the digestive pattern of dry fermented sausage proteins. The addition of starters resulted in a higher degree of proteolysis and looser protein conformation as evidenced by the decreased carbonyl content and electrophoresis bands intensity of myosin heavy chain (MHC) and actin, increased sulfhydryl content and surface hydrophobicity, and transformation of protein secondary structure from α-helix to β-sheet and β-turn. These changes induced by the starters acted as a "pre-digestion" step and improved the digestive pattern of sausage protein. The most remarkable improvement in gastric (33.98%-49.46%) and whole gastrointestinal digestibility (87.41%-94.57%) was observed on sausages of day 21. Comparative peptidomics analysis during digestion revealed that the digested peptides of the inoculated sample were more widely distributed throughout the 3D structure of the sausage proteins, namely, myoglobin, MHC, and creatine kinase M-type. More peptides were degraded in the rod region (780-1933) of MHC. The region was possibly expanded by starters. New bioactive peptides, including MNVKHWPWMK, FFL, and LLF, were released from the MHC and actin altered by the starters. This work highlighted the application of mixed starters as a potential tool to enhance the nutrition of fermented sausage.