The Anti-freeze And Water-holding Capacity Of Carrageenan Oligosaccharides And Xylooligosaccharides On Litopenaeus Vannamei

The water retention of frozen shrimp products are closely related with the products' quality.However,the protein denaturation,organization structure deterioration,moisture content reduce,sensory traits and edible value decrease happed during the frozen storage.Therefore,how to improve the water retention of frozen shrimp products and prevent protein freezing denaturation is a research hotspot in aquatic products processing.The aim of this work was to evaluate the cryoprotective effects and water-holding capacities of xylooligosaccharides and carrageenan oligosaccharides on white shrimp?Litopenaeus vannamei?during frozen storage using sodium pyrophosphate as the positive control,and then investigated the mechanism of water retention of xylooligosaccharides and carrageenan oligosaccharides,which providing the theory basis for the application of a new kind of low-sweet,low-calorie,natural and efficient additive,meanwhile ensure the product quality and safety in shrimp processing.The main research contents and conclusions of this paper are as follows:1.The aim of this part was to evaluate the cryoprotective effects of xylooligosaccharides and carrageenan oligosaccharides on peeled shrimp?Litopenaeus vannamei?.The results indicated that the xylooligosaccharides and carrageenan oligosaccharides treatment significantly decreased the thawing loss,inhibited the degradation of myofibrillar protein and Ca²⁺-ATPase activity,and maintained the stability of textural and color properties of shrimp muscle,compared with the control batch during the frozen storage.Significantly,3.0%?w/v?of xylooligosaccharides and carrageenan oligosaccharides treatments showed better cryoprotective effects on water-holding properties of shrimp muscle than its 1.0%?w/v?treated-batches.The microstructure analysis results revealed that the tissue structure of shrimps treated with 3.0%xylooligosaccharides and carrageenan oligosaccharide were compact,which also showed good integrity,meanwhile,there were no significant differences in muscular tissue structure when compared with fresh shrimps after the frozen storage.2.The aim of this part was to evaluate the effect of added xylooligosaccharides and carrageenan oligosaccharides on the cryoprotective effects and storage quality of frozencooked white shrimp?Litopenaeus vannamei?.The results indicated that the thawing and cooking loss of shrimp were significantly?P<0.05?decreased by xylooligosaccharides and carrageenan oligosaccharides treatment.The a* value of cooked shrimp was maintained significantly?P<0.05?better by xylooligosaccharides and carrageenan oligosaccharides than sodium pyrophosphate treatment during the whole frozen storage,which indicated that the two saccharides had good cryoprotective effects on the color of frozen cooked shrimp.In addition,the xylooligosaccharides and carrageenan oligosaccharides treatment significantly decreased the water activity,inhibited the degradation of moisture content and texture of frozen cooked shrimp.The microstructure analysis revealed that the tissue structure of shrimps treated with xylooligosaccharides and carrageenan oligosaccharides were compact,showing no significant difference when compared with fresh cooked shrimps.3.The aim of this part was to evaluate the effect of added xylooligosaccharides and carrageenan oligosaccharides on myofibrillar protein?MP?oxidation of frozen white shrimp?Litopenaeus vannamei?.The results indicated that the carbonyl content,surface hydrophobicity and the content of dimer tyrosine of shrimp were significantly decreased by xylooligosaccharides and carrageenan oligosaccharides treatment,compared with distilled water treatment.In addition,the xylooligosaccharides and carrageenan oligosaccharides treatment significantly inhibited the degradation of the total sulfhydryl content and the?max of endogenous fluorescence of frozen cooked shrimp.SDS-PAGE gel electrophoresis showed that 3.0% xylooligosaccharides and carrageenan oligosaccharide can alleviate the decomposition of protein,maintain the integrity of muscle protein.4.The aim of this part was to investigate the cryostabilization mechanisms by xylooligosaccharides and carrageenan oligosaccharides during frozen storage of shrimp by using molecular dynamics MD simulations.The results indicated that xylooligosaccharides and carrageenan oligosaccharides reduced the flexibility of particular amino acid residues,enhanced the residue cross correlations within the two chains of myosin,improved the consistency and cooperativity of internal chain motions markedly.In addition,xylooligosaccharides and carrageenan oligosaccharides also increased the total interaction energy though van der Waals forces and electrostatic interaction forces between myosin and water/saccharide molecules,thereby leading to an increase in protein stability.