Study On Physicochemical Properties Of Scallop (Patinopecten Yessoensis) During Frozen Storage

Scallop (Patinopecten yessoensis) is one of the major aquaculture species in the north of China. And its resource is very rich. Scallop contains high-value nutritional elements and a variety of bioactive substances and popular with people. In addition, frozen storage is one of the main processing way of adductor muscles for export and the domestic market. However, the quality of scallop will decrease, even lose its nutritive value during frozen storage. So, it is important to study the denaturation mechanism of scallop and the cryoprotective effect of anti-freeze agent during frozen storage.In this study, the changes of physicochemical properties of actomyosin in scallop adducter muscles (SAM) and scallop adductor muscle mince(SAMM) were investigated during frozen storage, including the salt solubility, Ca2+-ATPase activity, Mg2+-Ca2+-ATPase activity, the contents of active thiol and total thiol. The water-holding capacity and cooking loss of SAM were also investigated. Meanwhile, the cryoprotective effect of 3 kind of scallop skirt protein hydrolysates (SSHs) in frozen SAMM was also evalued. The results were as follows:(1) During frozen storage of SAM, all the values of above physicochemical indicators declined, but the water-holding capacity and cooking loss increased during frozen storage both at -18℃ and -35℃. Comparing with all the values of above indicators at -18℃, the corresponding values of SAM at -35℃ were higher and the water-holding capacity and cooking loss were lower. It indicated that the lower the storage temperature, the better the physicochemical properties and the better the water-holding capacity.(2) All the values of above parameters of physicochemical properties of SAMM declined as the time prolonged at -18℃ and -35℃, which was similar to those of SAM. Protein denaturation became serious from the 6th to the 10th month at -18℃, and the denaturation rate increased to 11.28%,20.31%,30.36%,68.49% and 83.67%, respectively. Besides, all the values of the corresponding indicators of SAMM at-35℃ were reduced to 60.01%,45.25%, 48.17%,82.80% and 88.71% of the original level respectively at the end of 10 month. Therefore, it was better for SAMM to be storaged at-35℃.(3) Scallop skirt was hydrolysed by papain, flavourzyme and alkaline protease to get SSH-P, SSH-F and SSH-A, respectively. SSH-P, SSH-F, SSH-A and sucrose-sorbitol (SuSo, 1:1) were added in SAMM respectively. All the mixtures were freezed and thawed for 6 cycles. Results showed that, comparing with the control group (without any cryoprotective agents), all the 3 SSHs showed cryoprotective effect on the physicochemical properties of SAMM. SSH-A demonstrated the best protective effect both on the salt extraction protein content and cooking loss of SAMM. SSH-F showed the best protective effect on Ca2+-ATPase activity of SAMM, which was same with SuSo. SSH-P had the best protective effect on total thiol content, and SSH-F demonstrated the best protective effect on active thiol content of SAMM.