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.