Effects of high hydrostatic pressure on protein and microstructure of Litopenaeus vannamei

High hydrostatic pressure (HHP) is a promising non-thermal food processing technology, which not only can inactivate microorganism and enzyme to ensure food safety, but also can maximize the retention of nutrients and color, aroma, taste and improve food texture and functional properties. HHP can maintain the balance of food safety and quality better. At present, HHP has been widely studied and applied in meat processing, seafood processing, fruit and vegetable processing, dairy processing, and so on. In recent years, HHP has been reported in the shrimp preservation and processing. For example, HHP can inactivate microorganism and polyphenol oxidase from Litopenaeus vannamei, but HHP has a little effect on qualities. HHP can also be used to shuck, eliminate allergens, and extract astaxanthin from by-products in the shrimp processing. These provide a new method for shrimp processing and utilization. In order to enrich the basis theory of HHP in shrimp preservation and processing and to realize industrial production, regarding untreated peeled shrimps as a control, the peeled shrimp were treated by HHP at 100, 300, 500 MPa for 5, 10, 20 and 30 min, respectively. The content, composition and thermostability of protein were analyzed. The microstructure of shrimp muscle tissues was observed by optical microscope and transmission electron microscope. The results showed that the content of sarcoplasmic protein slightly increased at 100 MPa, and decreased significantly at 300 and 500 MPa, and the content of myofibrillar protein significantly decreased. HHP treatment resulted in denaturation of peeled shrimp protein and decreased the thermostability of myosin and actin. With the increase of pressure and treatment time, HHP makes the arrangement of peeled shrimp myofibril tight and compact, and even the structure of myofibril collapse, sarcomere severe contraction, the gap among muscle fibers fuzzy and showing a flocculent structure. Therefore, high hydrostatic pressure can cause shrimp protein denaturation and gelation, which is conducive to digestion and absorption of the human body. The results show that high hydrostatic pressure can be used for processing instant shrimp products.