Study On The Free Radical Production In The Autolysis, Processing And Storage Of Aquatic Products Using Electron Spin Resonance Technology

Sea cucumber Stichopus japonicus(S. japonicus) and shellfish are common aquatic products, not only are consumed as food and fuctional food, but also possess a high economic value. Under the stimulation of the external environmental factors, S. japonicus prone to autolysis, this phenomenon caused huge losses of economic and nutrition during the sea cucumber storage, preservation, processing and transportation. It brings a lot of inconvenience. Shellfish muscle is tender, and it is easy to spoilage after capturing. To rich autolysis theory of sea cucumber and the theory study of aquatic products processing and storage, to resolve the problem caused by autolysis of S. japonicus and lipid oxidation in aquatic products processing, in this study, S. japonicus, scallop(Placopecta magellanicus), Venerupis variegata, Ostrea Talien whanensis, Haliotis gigantea discus were used as materials. DMPO and POBN were used as spin trapping agent, free radicals were detected using electron spin resonance(ESR) during autolysis and the processing and storage of aquatic products.The results showed that hydroxyl radical(OH·) was produced and the ESR signal peak was highest under the condition of 10 mg/m L under UVA irradiation for 20 min. ESR signal strength discreased with the increase of concentration of mannitol, SOD and catalase; the optimum p H of OH· production was at the range p H 7-8. In the research on detection free radical formation using ESR detection during aquatic product processing, lipid free radical generation increased with the heating time extended, and at the same heating time, the higher the heating temperature, the higher free radical yield. After heating for 5 h at 55 oC, 75 oC and 95 oC, free radical ESR signal peaks were 4.483×105, 10.25×105 and 13.28×105, respectively. Lipid free radicals in Venerupis variegate, Ostrea talien whanensis, and Haliotis gigantea discus increased with prolongation of heating time. Heating for 5 h at 75 oC, the free radical signal peaks intensity of ESR were as follows: Venerupis variegate 1.92×105, Ostrea talien whanensis 5.93 ×105, Haliotis gigantea discus 0.83×105. Heating for 5 h at 95 oC, the free radical signal peaks intensity of ESR were as follows: Venerupis variegate 9.44×105, Ostrea talien whanensis 25.71×105 and Haliotis gigantea discus 16.92 ×105.The highest lipid free radical in Ostrea talien whanensis presented at 0 d, the ESR signal peak value was 2.28×105, and the lipid free radical decreased with the storage time extended. The amount reached the lowest at storage of 60 d, the ESR signal peak was 0.58×105. The lipid free radical in Haliotis gigantea discus was lowest in the several shellfish, nearly didn’t chage with the storage time extended. The lipid free radical in both of Placopecta magellanicus and Venerupis variegata significantly increased after storage of 1 d, then Placopecta magellanicus showed decreased tendence with the storage time extended. The amount of lipid free radical was lowest at the storage time of 60 d, the ESR signal peak value was 0.53×105. The lipid free radical in Venerupis variegata didn’t have significant tedence, the amount of free radical was lowest at the storage of 30 d, the ESR signal peak value was 0.49×105, was highest at the storage of 60 d, the value was 1.11×105.The study in free radical production by ESR technology provided the theoretical basis for chemical changes in autolysis, processing and storage of aquatic products. It also supplied basis for the application of ESR technology in the field of aquatic product.