| One of characteristics of cold water fish in Xinjiang,Coregonus peled,which favored by domestic and foreign aquatic markets at present.Due to a feature that Coregonus peled will dead once it leave the water,it can only be processed or stored and sold everywhere.However,the aquatic products are prone to protein oxidation and constraints of geographical factors in Xinjiang caused to fish putrefaction during processing and storage,as a result,the economic benefits reduced greatly.Therefore,Coregonus peled was used as the object of this study,and the muscle was oxidized by hydroxyl radical-generating system in vitro,then stored under the condition of refrigeration,partial freezing and frozen,changes of textural properties and tissue structure of the muscle were observed,on this basis,the effect of three non-muscle protein additives(soy protein isolated,gluten powder and whey protein)on inhibiting the destruction of muscle textures were studied.In order to provide the theoretical basis for researching the deterioration of Coregonus peled muscle structure caused by protein oxidation in the process of fresh-keeping.1 By simulating hydroxyl radical-generating system in vitro to oxidize the Coregonus peled muscle,under 4? refrigerated condition,the sensory evaluation results showed that the sensory scores of the control and oxidation groups dropped to 9.17 and 6.25 after stored 10 days,respectively,and the oxidation treatment group had reached an unacceptable level.The pH value of fish muscle showed a downward trend in earlier stages of storage and then showed an upward trend with the storage time increased and the pH value of the control group and the oxidation group showed significant differences in the same storage time.The electroconductivity showed an upward trend during storage.The change in texture characteristics showed that except for the increasing of the adhesiveness value,all the other parameters showed a downward trend,which corresponds to the decrease of the sensory evaluation result.Compared with the control group,the texture characteristics of the oxidation group decreased more significantly,and the damage to the texture quality of fish was more obvious.Therefore,the shelf life of the control group and the oxidation group under refrigerated conditions was 12 d and 8d,respectively.2 Under-3? partial freezing condition,the changes of parameters such as sensory score,pH value and textural properties of control group and oxidation group were similar to those under refrigeration during the 49 d storage period.The sensory evaluation results showed that the sensory score of the oxidation group dropped to 6.5 after stored 35 days,which has reached an unacceptable level,and the sensory score of control group dropped to 8.0 after 42 days,has reached to the shelf life.After storage for 49 d,the pH value both gone up to a maximum value 6.95 and 7.11,and higher 2.51% and 5.65% than initial pH value,respectively.The electroconductivity of samples reached the maximum at the end of storage,and the oxidation group was higher 13.44% than the control group.The water-holding capacity decreased by35.59% and 43.96%,respectively.Hardness,springiness,gumminess,chewiness,cohesiveness,resilience and shear force value dropped to the minimum,while the adhesiveness rose to the maximum at the 49 d,and increased by 88.55% and 92.68% respectively compared with the initial values.Moreover,the musclestructure of the control and oxidized fish samples ruptured due to the protein denaturation and degradation and ice crystal during storage,and the oxidized samples changed more significant.Therefore,the acceptable storage time of the control and oxidized group under the storage condition is about 35 d and 28 d,respectively.3 At-24? frozen storage condition,during the 90-day storage period,the sensory score of the control and oxidized fish samples still within the acceptable range.The changes of pH value showed a downward trend with the extension of storage time,and fell to the minimum after 90 days of storage.Furthermore,the changes of electrical conductivity,water-holding capacity,texture parameters and shear force value were similar to those of refrigeration and super chilling storage.After storage for 90 days,the electrical conductivity increased by 73.22% and 64.47% respectively,the hardness individually decreased by 54.34%and 53.41%,the springiness gone down 29.50% and 36.85% respectively,the cohesiveness fell by 18.31%and 29.12% respectively.And the gumminess decreased by 55.55% and 66.92%,the chewiness decreased by 67.36% and 87.69%,the resilience fell by 39.52% and 45.43%,and the shear force value decreased by47.57% and 61.91%,respectively.While the adhesiveness increased by 76.82% and 92.46%,respectively,which indicated that the oxidized fish sample had lost its original viscoelasticity and became soft,and its original structure has been destroyed.4 The sensory scores and water-holding capacity of Coregonus peled treated with different non-meat protein additives showed a downward trend with the storage time increased,and the higher the storage temperature,the faster the decline rate.The electroconductivity showed an upward trend during storage and the higher the storage temperature,the faster the rise rate.Moreover,the GP addition group was lower than the SPI and WP addition group.The p H value of different treatment showed a “V” trend during refrigeration and partial freezing.And the pH value of SPI group sample showed a slowly decreasing trend,while the GP and WP group samples' pH value fluctuated during frozen storage.The hardness,springiness,cohesiveness,gumminess,chewiness and resilience of SPI,GP and WP treated groups showed a downward trend under different storage conditions,and the lower the storage temperature,the slower the decline rate.While the adhesiveness increased during storage.In addition,the texture parameters of GP treated group were significantly higher than that of SPI and WP treated group during the cold storage period.The hardness of different treatment samples showed nonsignificant difference in the same storage period under partial freezing and frozen storage.The adhesiveness of GP treatment group was significantly lower than that of the SPI group and the WP group,while there was no difference in the frozen storage period.The SEM observation results showed that the inhibition effect of GP treatment on the destruction of fish muscle structure was better,which remained relatively complete tissue structure during different storage periods. |
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