Fermented mash is made of mixed ground pork, koji, and salt and the supernatant liquid of fermented mash constitutes FMS. In order to assess the relationship between antioxidant activity in FMS and digestion of meat protein, the degree of proteolysis in fermented mash was examined by SDS–PAGE (Fig. 3). Myosin heavy chain (220 kDa) and actin (42 kDa) bands in fermentedmash disappeared after 1 week of fermentation. A new band of approxi-mately 23 kDa appeared at the same time point but disappeared at 8 weeks. Expression of other protein bands were reduced or com-pletely disappeared with fermentation over time. In addition, the concentration of water-soluble proteins in FMS also rapidly decreased with fermentation (Fig. 2), from a starting concentration of 58.86 mg/ml over a period of 4 weeks. The protein concentra-tions in FMS at 4 weeks decreased to approximately 87% of the starting concentrations prior to fermentation and gradually decreased after 8 weeks. The results indicate that FMS contains a considerable amount of peptides, since the proteins in fermented mash and water-soluble proteins in FMS are digested by proteases during fermentation.