Enhancing selenium and key flavor compounds contents in soy sauce using selenium-enriched soybean

•Se-enriched soybean markedly enhanced total Se and organic Se contents in soy sauce.•Se-enriched soybean facilitated flavor compounds formation in soy sauce.•Se-enriched soybean enhanced protease activities and microbial amount in moromi.•More flavor compounds in SeSS were generated by more proteases and microbials.