Lactic acid fermentation of kamaboko, a heated Alaska pollock surimi, enhances angiotensin I-converting enzyme inhibitory activity via fish protein hydrolysis.

To enhance the value of surimi, efforts have been made to develop a fermentation method with lactic acid bacteria (LAB) to proteolyze fish protein. However, fermenting unheated surimi poses a spoilage risk due to its high bacterial content. Surimi heat treatment can prevent spoilage, but gel formation induced by heating introduces another technical issue: it hinders uniform fermentation. Thus, this study aims to observe the proteolysis and enhance the functionality of seafood product through lactic acid fermentation of kamaboko, a heated surimi. Upon analyzing the kamaboko fermented with Lactobacillus helveticus JCM1004, we observed that LAB produced protease, resulting in the degradation of myosin heavy chain and actin during fermentation. Lactic acid fermentation significantly augmented the peptide content of kamaboko, subsequently elevating the angiotensin Ⅰ-converting enzyme (ACE) inhibitory activity in 200-fold diluted extract of fermented kamaboko to approximately 70% and higher. Notably, our investigation revealed that proteolysis was confined to the surface of kamaboko, as evidenced by SDS-PAGE analysis. This observation implies that the surface area of kamaboko influences the ACE inhibitory activity. Through a comparative analysis of various bacterial strains, we demonstrated that the increase in ACE inhibitory activity is contingent on the protease generated by LAB. These results suggest that LAB-mediated proteolysis of fish proteins liberates bioactive peptides, thereby manifesting in the ACE inhibitory activity. In summary, this study underscores that the fermentation of kamaboko employing proteolytic LAB holds promise in the development of novel functional seafood products.

Processing Alaska Pollock Protein (Theragra chalcogramma) into Kamaboko Protein Mitigates Elevated Serum Cholesterol and Postprandial Glucose Levels in Obese Zucker fa/fa Rats.

Fish paste products such as kamaboko (KB) are traditional Japanese foods prepared from fish meat. The health-promoting properties of fish proteins and their lysates include improving glucose and lipid metabolism. Although the KB manufacturing process and quality have been examined, limited studies have reported the health-promoting function of KB. This study aimed to evaluate the effects of processing Alaska pollock protein (APP) into KB protein (KBP) on serum lipids levels and postprandial glucose tolerance. Obese male Zucker fa/fa rats were fed on different diets for 4 weeks as follows: APP group, fed on a diet in which APP constituted 25% of total protein intake; KBP group, fed on a diet with APP-processed protein as the protein source; control group, fed on a diet with 100% casein as the protein source. Compared with those in the control group, the serum total cholesterol (TC) level was reduced and the elevated postprandial blood glucose level was mitigated during the high-carbohydrate meal tolerance test in the APP and KBP groups. Further, KBP exerted significantly higher effects on serum TC levels and glucose tolerance than APP.