| This study researched different concentrations of Chain fatty acids purified river crab,detected the influence on taste quality of edible parts,and preserved crabs at 4 ? condition after purification treatment,observed it is or not good for to extend the viable period and storage period of crabs,in order to explore the best purification concentration,offer help to perfect discriminant quality index and evaluation system of crabs.Research has shown that: the components of medium-chain fatty acid is a pale yellow liquid,no flocculated sludge,the effective antimicrobial were nonyl acid,bitterness,kwai acid,and active matter content of 10.46% on average good stability,no corrosion to stainless steel pieces,for carbon steel sheet moderate corrosion,and corrosion of copper,aluminium is mild.The average killing logarithm values of the Candida albican and Pseudomonas aeruginosa exposed to the 350mg/L dilution for 7.5min was above 5.00.The average killing logarithm values of the Escherichia coil and Staphylococcus aurrus exposed to the 200mg/L dilution for 7.5min was greater than or equal to 5.00.The average killing logarithm values of the Bacillus subtilis var.niger spores in suspension exposed to the 500mg/L dilution for 22.5min was 0.50.Toxicity test results show that the components of medium-chain fatty acid belongs to actually non-toxic grade material.Mouse bone marrow polychromatic erythrocyte micronucleus test was negative.Therefore,components of medium-chain fatty acid has good germicidal efficacy and the safety of the use.Female crab purchased from Chong ming as the main research object,using deionized water dilute components of medium-chain fatty acid diluent into 50 ? 100 ? 150 mg/L,The clean-up condition for solid-liquid ratio with crabs,fatty acid dilute solution = 1:10,20 min.Results show that whether raw or cooked state,total free amino acid of river crab edible parts tend to increase before falling with increased concentration of fatty acid dilute solution.Fresh crabs was no detection in the gonad aspartic acid(Asp),three edible parts of cooked crabs are all do not detect cysteine(Cys).Gly,Ala,Arg and Pro the four accounts for larger in the crab body assumes the change trend of amino acid and free amino acid,total crabs from fresh to cooked state,each flavor amino acids accounted for little change.The FAA composition of hepatopancreas changes mainly in SFA and BFA.The nucleotide content of river crab gonad higher 1 ~ 2 orders of magnitude compared with the other edible parts,fully shows that the female crab gonad have strong freshness compared with other organizations.With the increase of processing liquid concentration,IMP and AMP content of raw muscle showed a trend of decline,GMP trend opposite;IMP content in the gonad present gradually rise,while the opposite the change trend of GMP and AMP.After Cooked the AMP content of gonads become the highest,Other experimental AMP levels were significantly higher than the control group.5 '-nucleotide content in muscle and hepatopancreas decreases gradually with the increase of processing liquid concentration.Crabs in fresh state,muscle of flavor contribution reduce gradually with the increase of processing liquid concentration,Ala and IMP contribution in the gonads tend to increased,Ala and Arg of hepatopancreas also showed the same trend.Crabs in cooked state,the strongest of muscle of flavor contribution is Arg,and the strongest of gonad of flavor contribution is AMP,IMP flavor contribution greatly reduced after cooked;AMP flavor contribution of hepatopancreas greatly significantly increased through high temperature after cooked.River crab gonad MSG equivalent is far higher than that of muscle and hepatopancreas,river crab of fresh state gonad MSG equivalent distribution in 37~54 g/100 g.After high temperature cooked hepatopancreas freshness strength increased,but muscle and gonads freshness greatly reduced,That is to say the overall umami of crabs raw state is superior to the cooked.Refrigeration experimental results show that the sensory score of river crab dropped with the extension of storage time,survival time for 5 ~ 6 d.After crab death the smells and crab roe structure score of 100 mg/L group and 150 mg/L group is significantly higher than control group;microbial counts and coliform group count of river crab are high,respectively was 6.18 lg lg(CFU/g)and 5.83(CFU/g),it may not be appropriate for eating without treatment.The TVBN value of crab before death cannot effectively evaluate its freshness,but TVBN mutated from dying to death.,later TVBN present a trend of first increased after falling again increased with the time.TBA has been increasing during the crabs storage,100 mg/L,150 mg/L treatment group has been lower than the control group,help to inhibit oxidative decomposition of unsaturated fatty acid,significantly lower than the control group were 23.5%,24.7% at the end of the storage.Above all,100 mg/L diluent of components of medium-chain fatty acid purified crabs can maintain its original freshness,and can be to keep the original quality in cold storage period,beneficial to prolong the shelf life. |
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