Hydrolysis of Pork Myofibrillar Proteins during Fermentation Using Starter Cultures of Lactobacillus bulgaricus and Streptococcus Thermophilus

We examined the effects of Lactobacillus delbrueckii subsp. bulgaricus (Lb. bulgaricus) and Streptococcus thermophilus (St. thermophilus) starter cultures on the proteolytic processes occurring in fermented pork. The hydrolysis of myofibrillar or myosin B proteins was evaluated using SDS-PAGE. Significant hydrolysis was observed in myofibrillar proteins from the fermented pork with lactic acid bacteria (LAB) cultures and the incubated pork with glucono-delta-lactone (GDL), in contrast to the control sample incubated without LAB or GDL. Although the specific proteolytic activities of each strain towards myofibrils were unclear, their hydrolysis of myosin B was clearly demonstrated. We concluded that myofibrillar protein hydrolysis occurring during the fermentation of pork is due to the combined action of meat endogenous proteases and proteases from Lb. bulgaricus and St. thermophilus.