Changes In The Quality Of Flavoured Crab Paste During Fermentation, And Research On Antioxidant Function Of The Product

Crab paste is a traditional seasoning in China's coastal areas,which has unique flavor and full of nutrition.But it lack of quality assessment methods because of the completely open process during the fermentation.Due to its inherent fishy smell,its consumer acceptance and economic value was low.Therefore,in order to further improve the market circulation rate and economic value of Jinzhou crab paste in Bohai,this paper intends to use the low value crab of the Bohai Sea?Charybdis japonica?as raw material,in order to improve the market circulation and economic value of Jinzhou crab paste.Reveal the changes in sensory characteristics,physical and chemical parameters and flavor quality during the fermentation process and the correlation between sensory characteristics and physical and chemical indicators.The seasoning process for mature crab paste was optimized by Box-Behnken response surface design,and the product quality was analyzed,and a shelf-life prediction model for flavoured crab pastewas established.Preliminary exploration of the antioxidant activity of crab paste water extract The specific experimental content and conclusions were as follows:?1?The crab paste was prepared from the low value sea crab of Bohai as raw material,to observe the relationship between sensory properties?crab flavor,fermented flavor,fishy smell,umami,ammonia smell,salt taste,sweet taste,bitter taste,texture and color?and physical-chemical properties?moisture,pH,total acid,crude protein,crude fat,amino acid nitrogen,reducing sugar and TVB-N?of different fermentation stages through correlation analysis and regression analysis.The sensory and physiochemical correlation analysis showed that:There was a significant?p<0.05?or extremely significant?p<0.01?linear correlation between crab flavor,fermented flavor,fishy smell,umami,ammonia smell,salt taste,sweet taste,bitter taste,texture and color and moisture,pH,total acid,crude protein,amino acid nitrogen,reducing sugar,and TVB-N indicators.And pH,total acid,crude protein,amino acid nitrogen and TVB-N can be used to construct a crab regression sensory characteristics regression prediction model.The predictive model variance interpretation rate of crab flavor,fermented flavor,fishy smell,umami,ammonia smell,salt taste,sweet taste,bitter taste,texture and color were 69.1%,88.4%,90.5%,68.7%,67.3%,88.2%,65.7%,63.3%,94.1%and 90.1%.respectively,and regression equations obtained by stepwise regression analysis showed that moisture,pH,total acid,crude protein,amino acid nitrogen and TVB-N have important influence on the quality of crab paste,and can achieve its prediction and analysis of sensory quality.?2?The change of odor characteristics at each stage of crab paste fermentation was monitored by electronic nose.And SPME-GC-MS was used to analyze the composition of specific volatile components and their changes in the fermentation process.The results of electronic nose analysis showed that smell of crab paste has changed significantly at each stage,and electronic nose could be used for the rapid detection and analysis of crab paste.82compounds of 8 categories were identified by SPME-GC-MS,while 1-octen-3-ol,1-penten-3-ol,3,5,5-trimethyl-2-hexene,2-Higher levels of heptanone,2-indone,etc.,are basic stability during fermentation;isoamyl alcohol,6-methyl-2-heptanone,trimethyl pyrazine,tetramethyl pyrazine and dimethyl was not detected in the sample before fermentation,and it was a newly generated aroma component through the fermentation process.The content of alcohols,small molecules heterocycles and aromatic substances in fermented crab sauce increased accordingly,and the contents of aldehydes and hydrocarbons decreased accordingly,making the overall aroma coordination and compatibility harmonious.?3?Taking the sensory evaluation as the evaluation index,the single-factor experiment and the Box-Behnken response surface design were used to optimize the crab paste seasoning process.On the basis of single-factor experiments,the amount of soy sauce added,the amount of white vinegar,and the amount of white sugar added were selected,the main factors are response surface optimization.Physical and chemical indicators?moisture,crude protein,crude fat,and crude ash?,microbial indicators?total colony counts,coliform bacteria,Vibrio parahaemolyticus,Salmonella?,and volatile flavor components were determined.The crab paste products after high temperature sterilization were stored at 18°C,28°C and 37°C.The sensory indexes,physical and chemical indicators?pH,TVB-N?and the total number of colonies were periodically sampled and the sensory scores were calculated.The Pearson correlation coefficient between each indicator's value determines the key influencing factors and establishes the shelf life prediction equation.The final recipe for the flavored crab sauce was:crab sauce 100 g,cooking oil 10 g,cooking wine 10 g,raw soy sauce 7 g,soft white sugar 5 g,white vinegar 4 g,minced garlic 4 g,ginger 3 g,chilli powder 0.5 g.And the physicochemical and microbiological indicators test results show that finished crab sauce products comply with relevant national standards.43 kinds of volatile flavor substances were detected in the flavoured crab paste.Heterocycles,alcohols,sulfur compounds,hydrocarbons,ketones and ethers contributed a lot to the aroma of flavoured crab paste.The pearson correlation coefficients of sensory scores and index values during storage showed that the TVB-N value is a key influencing factor and the prediction equation for the shelf-life was established.The relative error between the actual shelf life of the flavored crab paste stored at25?and the predicted value of the kinetic model was only 3.65%.This indicates that this model can be used to predict shelf life theoretical values of flavoured crab paste at a given storage temperature.?4?Water-soluble active substances in crab paste were extracted,and antioxidant capacities in vitro?including the determination of DPPH free radical scavenging activity,the determination of superoxide anion free radicals and the determination of total reducing ability?were analyzed.The survival rate and antioxidant index of the cells treated by water extracts of crab paste with different concentrations were determined.Further explore its effect on the repair of oxidative stress injury of human vascular endothelial cells.The results showed that the water extract in crab paste was a strong antioxidant,and its concentration and antioxidant activity had a good dose-effect relationship.The survival rate of oxidative damage cells was increased by 40.2%after treatment with high concentration water extract of crab paste.And the activity of T-AOC and sod in oxidative damage cells could be improved,and MDA content could be decreased,which a certain effect on oxidative injury of human vascular endothelial cells had induced by H₂O₂.