Study On The Volatile Compounds And Their Combination To Proteins Of Silver Carp

Freshwater fish resources is abundant and production has been increasing yearafter year in our country.However,the development of freshwater fish products especially freshwater fish surimi products is limited due to its characteristic fishy and other odors which are hard to be accepted by consumers.It was hard to conduct the deodorization because some particular molecules like ketones,aldehydes and alcohols which produced from lipid oxidation reaction can be further interacted with large molecules like proteins in fish.Thus,how to remove the fishy aroma substances effectively is significant in aquatic products processing industry.Silver carp,a kind of common fish characterized by growing fast,low cost and high production,is widely used for the surimi production.In this study,the volatile substances and odor activity compounds in silver carp were first analyzed,and then the effects of different rinse mediums on the removal of these compounds and the content of main proteins were discussed,at last the combination between the key aroma substances and fish main proteins was also studied.The results were as follows:?1?Three methods including Simultaneous distillation extraction?SDE?,solid phase micro extraction?SPME?and solid material adsorption extraction?MMSE?were used to extract the volatile flavor compounds of silver carp surimi,31,40,60 kinds of volatile compounds were detected by GC-MS respectively.Combined with the odor activity value?OAV?method,17 odor active substances were determined from surimi.?2?The pH value,total plate count,total volatile basic nitrogen?TVBN?,thio barbituric acid?TBA?and K-value of the Silver carp surimi kept changing during storage at 4?for 8 days.The composition and content of volatile flavor compounds in surimi also presented a great difference,and the odor smell has been strengthened because of the lipid oxidation reaction and the growth of microorganism.?3?Six kinds of different rinse mediums were used to rinse silver carp,including distilled water,0.5%NaCl solution,0.35%Na₂CO₃ solution,0.5%NaCl+0.35%Na₂CO₃ solution,9%Urea solution and 0.05%Tween solution.Considering the changes of the content and composition of volatile substances and the main odor activity compounds,and the content of total protein,myofibrillar protein,sarcoplasmic protein and actomyosin,0.5%NaCl+0.35%Na₂CO₃ solution was proved to be the best for rinsing.?4?The main protein of surimi was able to combine with some main odor compounds including hexanal,heptanal,octanal,nonanal,1-octene-3-alcohol and E,E-2,4-decadienal,but the adsorption capacity of each protein to these compounds was different because of its particular structure;The adsorption capacity of protein with the odor activity compounds could be improved by the added concentration of each protein within certain limits.But when the concentration raised higher,the enhanced interaction of protein molecules would affect its combination with the flavor compounds thus resulted in lower adsorption ability;The increasing of NaCl concentration would also enhance the interaction of protein molecules and then reduced its adsorption ability.The protein conformation can also significantly affect the adsorption capacity of proteins to the key aroma active substance.