Effects Of Immersion Chilling And Freezing(ICF)on The Quality Characteristics Of Crisp Grass Crap

Crisp grass craps are more and more popular with customers own to their crisp texture,high protein and good taste. The main storage is frozen storage for crisp grass crap, with the extension of frozen storage,it can cause a series of reaction, including protein denaturation, water loss, tissue damage and taste becoming worse, Which could cause protein quality declined.In this project, taking fresh crisp grass crap as raw material,choosing immersion solution further. Research on effect of different freezing processing conditions for crisp grass crap. In order to prevent protein from denaturation,it’s important to optimize cryoprotectants.And research on effects of immersion chilling and freezing(ICF) combined with cryoprotectants for crisp grass crap.The main research contents and conclusions of this paper are as follows:In this project, ethanol, propanediol, betaine and sodium chloride.A Box-Behnken solution was used to explore optimal immersion solution formulation.A freezing point of-66.10℃ was observed for an a aqueous immersion solution containing, on a total dipping solution weight basis, 20% ethanol, 10% propanediol, 7% betaine and 10% sodium chloride, respectively.The above the optimal immersion solution formulation was applied for the freezing of crisp grass crap. Effects of different of freezing processing conditions on crisp grass crap.The result indicated that content of myofibrillar protein, Ca2+-ATPase, total-SH, hardness,springiness, chewiness and cohesiveness by immersion chilling and freezing(ICF)were higher than-18℃frozen. The results of physicochemical and textural characteristics indicated that immersion and chilling freezing could assist to reduce the denaturation of crisp grass crap protein.This paper was selected cryoprotectants, optimize the myofibrillar protein by response surface methodology. The concentration of trehalose, polydextrose, sodium lactate were3%~5%, 4%~6%, 3%~5%, respectively. Based on the single factor experiments and Box-Behnken experimental design.the results showed that concentration of trehalose,polydextrose, sodium lactate was 4%,6%,5%, respectively. The myofibrillar protein content was up to 176.60mg/g, which was higher than that traditional commercial cryoprotectants(4%sucrose+4% sorbitol), and can replace the traditional commercial cryoprotectants.The quality changes of crisp grass carp by control group, cryoprotectants group,ICF group,cryoprotectants combined with ICF group were studied and analyzed in the frozen storage for 6 months. Results showed that pH value, Total Volatile Basic Nitrogen(TVB-N),TBA, K value of cryoprotectants plus ICF group were lower than those values of control group, cryoprotectants group and ICF group. The values and changes of cryoprotectants group were similar to ICF group, and The values and changes of cryoprotectants group and ICF group were lower than that control group. The water-holding power of cryoprotectants plus ICF group was better than that the other three groups. Hardness, springiness,chewiness and cohesiveness of crisp grass crap were declined during the frozen storage,the extent of decrease of hardness, springiness, chewiness and cohesiveness on cryoprotectants plus ICF group were lower than that the other three groups. The content of myofibrillar protein, the Ca2+-ATPase activity, the total sulfhydryl and the active sulfhydryl of crisp grass carp were determined. The four indicators of cryoprotectants plus ICF group were higher than that the other three groups. The results indicated that cryoprotectants combined with ICF group can keep functional characteristics of protein. The infrared spectra of myofibrillar protein of crisp grass crap by different processing during frozen storage was determined.The results indicated that the content of α-helix on four groups were gradually declined,while the content of β-fold,random coil and β-turn were increased.And orderly structure of cryoprotectants plus ICF group much more than that the other three groups. Cryoprotectants combined with ICF was benefit to maintain the stability of protein secondary during frozen storage.