Study On Single Rinsing Process Of Silver Carp Surimi And Its Effect On Frozen Storage Quality

Silver carp,as one of the"four kinds of common domestic fish",has high yield and low price,and is the main raw material fish for processing of freshwater fish surimi.In industrial production,the method for rinsing minced fish with 5 times of raw material weight of clear water and repeated for 3 times is usually used.The method not only causes excessive loss of fish nutrition but also causes waste of water resources due to a large amount of rinsing water,and at the same time,the wastewater after rinsing is easy to cause serious environmental pollution.In this study,a water-saving single rinse method was established using potassium chloride（KCl）,sodium citrate and carboxymethyl chitosan（CMCS）as rinse agents.In addition,because surimi products often need the shelf characteristics of cold chain transportation and frozen storage,the effects of industrial three-time rinsing method（NR）and the optimized carboxymethyl chitosan and compound salt single-time rinsing method（OR）on the gel characteristics and flavor of frozen surimi were explored and compared.Furthermore,the related mechanisms of OR rinse method in delaying the deterioration of frozen surimi quality were preliminarily explored from the perspectives of lipid oxidation,protein oxidation and gel rheology.The main research contents and results are as follows:（1）Using KCl,sodium citrate and CMCS as rinsing agents,a compound single-time water-saving rinsing method suitable for silver carp surimi was developed.The strength,texture,whiteness and water-holding capacity of surimi gel were used as indicators for single factor experiments.The comprehensive quality of surimi gel could be significantly improved when the rinse solution was 1.0%KCl（w/v）,0.15%sodium citrate（w/v）and1.2%CMCS（w/v）,respectively.On this basis,the single rinsing method of 1.0%KCl（w/v）+0.15%sodium citrate（w/v）+1.2%CMCS（w/v）was determined to be the best by performing four combined rinsing schemes with the three rinsing agents.The gel strength of rinsed surimi was 365.62 g·cm,the whiteness was 75.11,the water holding capacity was 87.12%,and the yield of surimi was 74.41%.Compare with that industrial three-time rinsing method,the rin method not only can effectively improve the comprehensive quality of the surimi,but also can reduce the rinsing times and the rinsing wat consumption,thereby achieving the purpose of saving the surimi rinsing water.（2）Two rinsing methods NR and OR were used as the research objects to explore the changes of gel properties and flavor of rinsed surimi stored at-18℃for 60 days.The results showed that OR rinse protected the integrity of surimi gel network structure,which was conducive to alleviating the deterioration of surimi gel strength,texture characteristics,whiteness and water holding capacity during the frozen storage period.The gel structure had fewer pores,and was uniformly and regularly arranged.It had a smooth network structure,which was conducive to prolonging the storage period of surimi gel.According to GC-MS analysis,a total of 53 volatile flavor compounds were identified in frozen silver carp surimi.With the prolongation of freezing time,the relative content of alkanes and alkenes rinsed with OR was decreased less than that of NR,the relative content of alcohols was decreased more,and the relative content of aldehydes was increased less.The preliminary analysis showed that OR rinse could effectively alleviate the fishy smell of frozen silver carp surimi.（3）The mechanism of OR rinse delaying the deterioration of frozen surimi quality was preliminarily explored from the perspectives of lipid oxidation,protein oxidation and gel rheology.The results showed that KCl and sodium citrate in OR rinse could effectively remove fat,leaving no significant difference between TBA and NR of surimi at the frozen storage.OR rinsing could delay the decline of Ca²⁺-ATPase activity and inhibit the process of decreasing the percentage ofα-helix and protein structure disorder,which would help to protect the structural integrity of myofibrillar protein in surimi and inhibit protein denaturation.It can delay the oxidation of thiols and help delay the oxidation of proteins.Exposure of hydrophobic amino acids and shallowing of protein bands in the SDS-PAGE pattern were inhibited,which helped to inhibit protein degradation.Therefore,OR rinse had certain antioxidant and anti-freezing effects on surimi.The results of gel rheology showed that G’and G’of OR were higher than those of NR during frozen storage.OR rinse surimi could better improve the elasticity of surimi,facilitate the formation of surimi gel,and effectively delay the decrease of surimi elasticity during frozen storage.