F Boneprotein Hydrolyzates And Konjac Flour On Qualities And Sicochemical Properties Of Frozen Common Carp Muscle

This test selected out the best concentration of boneprotein hydrolyzates and konjac flour by the test of boneprotein hydrolyzates antioxidant properties and konjac gel properties firstly, then the boneprotein hydrolyzates and konjac flour were added to the common carp muscle in order to study their impact on quality and myofibrillar protein structural and functional and gel changes in common carp muscle during storage at-18℃systematically. The mechanism of boneprotein hydrolyzates and konjac flour what delayed frozen common carp muscle quality deterioration and protein denaturation were clarified by studying. The effectiveness of50%commercial cryoprotectants (2%sucrose+2%sorbitol) and100%commercial cryoprotectants (4%sucrose+4%sorbitol) in preventing frozen-induced perturbations of myofibrillar protein from common carp muscle subjected to frozen storage was compared to boneprotein hydrolyzates and konjac flour on the basis of obtained results, and the mechanism of boneprotein hydrolyzates and konjac flour in preventing the frozen denaturation of common carp protein was more learnt. The results were as follows:1. The antioxidant properties (metal ion chelating ability、free radical scavenging、TBRAs content of soft phospholipid lipid oxidation system) of boneprotein hydrolysates and the gel properties (springness、hardness、whiteness、water-holding capacity) of konjac flour were adopted to selected out the best concentration of boneprotein hydrolyzates and konjac. The results obtained that the antioxidant properties of boneprotein hydrolyzates were most remarkable at a4%concentration level and the gel properties of konjac flour were most significant at a0.5%concentration level. Considering the cost of production and the taste, the best concentration of boneprotein hydrolyzates and konjac flour is4%and0.5%, respectively.2. Boneprotein hydrolysates were added to the common carp muscle to study their impact on the quality of frozen common carp, the results obtained that the L*values and whiteness redused extraordinaryly with the increasing days during frozen storage; while the TBRAs、TVB-N、thawing loss and cooking loss increased. After180days of frozen storage, compared to the control group, the L*values and whiteness values of common carp muscle with the boneprotein hydrolyzates were increased by14.22%and4.60%; respectively; while the thawing loss, cooking loss, TBRAS, TVB-N decreased by44.07%,36.18%,66.13%and32.78%, respectively. These showed that the boneprotein hydrolyzate can increase water-holding capacity of frozen common carp muscle, delay the occurrence of fat oxidation and muscle color deterioration.3. The impact of boneprotein hydrolyzates and konjac flour on carp myofibrillar protein structural properties were studied, The results showed that the Ca2+-ATPase activity and the total sulfhydryl content decreased continuously, while the carbonyl content increased continuously with the increasing time of frozen storage. The boneprotein hydrolyzates and konjac flour can improve the Ca2+-ATPase activity and the total sulfhydryl content of myofibrillar protein and delay the increasing rate of carbonyl content. Among of them, the extent of the change of the samples with boneprotein hydrolyzates is significant especially (P<0.05). At the end of storage, the carbonyl content of the samples with boneprotein hydrolyzates decreased by28.57%; while the Ca2+-ATPase activity and the total sulfhydryl content were increased by88.89%and82.18%compared to the control group respectively.4. The impact of konjac flour on carp myofibrillar protein functional properties were studied, The results obtained that with the increasing time of frozen storage, emulsifying properties of myofibrillar protein decreased continuously and surface hydrophobicity increased continuously. Konjac flour can delay the decreasing rate of emulsifying activity index and emulsion stability index and improve the surface hydrophobicity of myofibrillar protein.5. The springness、hardness、whiteness and water-holding capacity of myofibrillar protein gel were adopted to study the impact of konjac flour on myofibrillar protein gel properties of common carp muscle during frozen storage. The springness、hardness、whiteness and water-holding capacity of gel showed declining trend during the frozen storage, while konjac flour can improve the deterioration of the properties of the gel and enhance the gel properties of myofibrillar protein effectively.6. Complexation with boneprotein hydrolyzates and konjac flour、commercial cryoprotectants with different concentrations (50%、100%) were added in common carp muscle. After180days of frozen storage, the studies showed that complexation with boneprotein hydrolyzates and konjac flour can prevent fat oxidation and delay the occurrence of protein denaturation significantly, the antifreeze effect of which was better than commercial cryoprotectants at a50%concentration level, their abilities of enhancing color and improving the emulsifying and the gel properties of myofibrillar protein were even better than commercial cryoprotectants at a100%concentration level, this is because the boneprotein hydrolyzates have the ability with better oxidation resistance, and konjac flour have the ability with excellent emulsifying and gel capacity, while konjac flour also have the better "film-forming" ability, so complexation with boneprotein hydrolyzates and konjac can delay the occurrence of fat oxidation and protein denaturation effectively.