Department of Food Technology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand
Application of high pressure, a minimal processing, has gained interest particularly in extending the shelf-life or modifying the texture of seafood, especially in shrimp. However, pressurization may render the products with different texture as compared with their fresh and heated counterparts. Therefore, the impact of high-pressure treatment (200, 400, 600, and 800 MPa for 20 min at 28°C) on black tiger shrimp muscle proteins in comparison with heat treatment (100°C for 2 min) was investigated. Differential scanning calorimetry thermogram indicated that high pressure up to 200 MPa for 20 min induced the denaturation of myosin and actin with subsequent formation of a network stabilized by hydrogen bond. An electrophoretic study revealed that the sample pressurized at 800 MPa or heated at 100°C was also stabilized by disulfide bond. L*, a*, and b* values, compression force, and shear force increased with increasing pressure (p < 0.05). The heat-treated sample had higher L*, a*, b*, and shear force (toughening) than the pressurized and fresh samples (p < 0.05). Pressure at different levels had no effect on weight loss (p ≥ 0.05). However, a weight loss of 27.89% was observed in the heat-treated sample. Proteolytic activity of crude extract from the pressurized sample at 200 to 600 MPa did not differ from that of the fresh sample (p < 0.05). Nevertheless, the activity in the heated sample and that of the pressurized sample at 800 MPa decreased, indicating the inactivation of endogenous proteases in the muscle.