Study On Detection And Removal Of The Off-flavor In Soldier Crab Sauce

The research object of this paper is the soldier crab sauce that fermented from fresh crab obtained from Beihai city in Guangxi.The detection and removal of off-flavor in crab sauce were investigated.The research contents and results are as follows:HS-SPME method was used to extract the volatile flavor of the crab sauce.GC-MS and GC-O technology combined with the method of detection frequency(DF)and aroma extract dilution analysis(AEDA)were used to analysis the main off-flavor which also validated by odour activity value(OAV)and flavor profile analysis(FPA).The results showed that the main characteristic flavor of the crab sauce was seafood flavor,followed by ammoniacal flavor,crab meat flavor,roasted meat and cheese flavor and weak stink flavor as well.32 kinds of odor-active substances were identified by GC-O/MS.They mainly contribute to seafood flavor,fishy smell,sulfur,scorched flavour,nutty flavor and so on.The compounds that DF more than 7 were trimethylamine,dimethyl sulfide,methyl mercaptan,1-octene-3-ol,2,3-Butanedione,2-Methylbutyl-aldehyde,heptanal,nonanal.These substances may contribute to the the main flavor in crab sauce.Volatile substances such as methanethiol,1-octene-3-ol,nonanal and dimethyl sulfur,heptanal,trimethylamine and tert-butylamine which OAV more than lwere the main contributor to off-flavor in crab sauce.They were the important compounds contributed to off-flavor in crab sauce.Three traditional deodorization methods including activated carbon adsorption,beta-cyclodextrins embedding and acid suppression(lower pH)was tested for effect of removing off-flavor in crab sauce.In single factor experiment,treatments with the addition of 12 g/100ml for activated carbon,beta cyclodextrins of 2.4g/100mland adjusting the pH to 3.0 were the optimal level for each,respectively.The effect to the treatments from high to low is beta-cyclodextrin>lower pH>activated carbon.Meanwhile,the optimal conditions for addition and processing time of activated carbon joint that of beta-cyclodextrin on removing off-flavor was content of 12g/100ml for activated carbon by treating 50 min with beta cyclodextrins of 2.2g/100ml by processing 60 min,the contents of trimethylamine,methanethiol,heptanal,nonanal and 1-octene-3-ol was reduced to 5.18±0.05?1.50±0.01?2.49±0.02?1.04±0.01?0.99±0.02 ?g/100 mL.Molecular distillation technology was investigated to the removal effect of off-flavor in crab sauce.Single factor experiment found that pressure,temperature distillation and speed of 16 mbar,40 ?,300 r/min were the more optimal conditions.Response surface optimization analysis was preformed to find the best optimum technology parameter.The most optimal level was that 16mbar of pressure,300 r/min of speed,and 40 ? of temperature in which obtained the sensory evaluation score of 90 and removal rate average of 75%for off-flavor in soldier sauce,the contents of trimethylamine,methanethiol,heptanal,nonanal and 1-octene-3-of was reduced to 4.31 ±0.03?1.30 ± 0.02?2.07±0.01?0.87±0.02?0.83±0.01?g/100 mL.