Cryoprotective Effects of Trehalose, Alginate, and its Oligosaccharide on Quality of Cooked-Shrimp (Litopenaeus vannamei) During Frozen Storage

The cryoprotective effects of trehalose, alginate, and its oligosaccharide on cooked shrimp were evaluated and compared with Na4P2O7 during frozen storage. Data indicated that significant inhibitory effects on decreases of water-holding capacity, water content, water activity, springiness, and chewiness values were more pronounced in trehalose-, alginate oligosaccharide-, and Na4P2O7-treated samples than in freshwater-treated samples. L* value analysis indicated that the saccharide-soaking-treatments showed positive effects on color stability of cooked shrimp. H&E and SEM studies indicated that the fibers of cooked shrimp from trehalose- and alginate-oligosaccharide-treated groups were arranged in a tighter manner than the control, and the extracellular space was significantly smaller than in control samples after 6 weeks of storage. The cryoprotective effects described above were probably due to the replacement of water molecules, concentration of water molecules near protein surface, ionic cross-linking action in muscle, or stability of tissue structures derived from trehalose and oligosaccharide in shrimp muscle. Practical Applications Frozen storage is the most common method for long-term preservation of cooked-shrimp products. However, some undesirable changes can occur during freeze/thaw process, such as protein denaturation, lipid oxidation, and decreased water-holding ability. Phosphates are widely used in shrimp products to reduce cooking loss, improve textural properties, increase water-holding capacity (WHC), retard oxidative rancidity, and develop color. However, excessive phosphate treatment may not only cause phosphate imbalance in the diet, which poses health concerns, but also decreases quality by rendering the shrimp translucent or crispy. For this reason, alternative additives that can retain water and reduce drip loss should be considered to minimize degradation and improve the quality of the shrimp products. This study provides information regarding the cryoprotective effects of saccharides on peeled cooked-shrimp during frozen storage. This application is of utmost interest, and might have widespread applications to extend the commercialization of refrigerated seafood to better guarantee quality and safety.