Changes in allergenic and antinutritional protein profiles of soybean meal during solid-state fermentation with Bacillus subtilis

•We selected and identified 12 major antinutritional proteins in soybean meal (SBM).•Protein degradation during fermentation was assessed by proteomic tools.•Fermentation mainly reduces trypsin inhibitor and beta-conglycinin in SBM.•Fermentation by Bacillus subtilis improves the nutritional quality of SBM.

Fermented soy-based products are believed to have improved nutritional qualities compared to non-fermented products; however, little is known about the biochemical changes that occur during fermentation. To investigate the changes in the protein profile during fermentation, soybean meal and Bacillus subtilis-fermented soybean meal were prepared. Soybean meal and fermented soybean meal were analyzed by two-dimensional electrophoresis and compared by image analyzer. Twelve major spots were selected and identified by Nano LC–MS/MS. The proteins identified were beta-conglycinin subunits, glycinin subunits, trypsin inhibitors, and sucrose-binding proteins. Seventy percent of the beta-conglycinin subunits were removed after 24 h of solid-state fermentation with B. subtilis. Fifty percent of trypsin inhibitors were removed after 24 h. Glycinin subunit degradation was the lowest, with 58% remaining after 24 h of fermentation. This study suggests that fermentation can improve the nutritional quality of soybean meal.