Study On Flavor Characteristics Of Five Dominant Aquatic Raw Materials And Their Fried Products In Guangxi

Flavor is one of the important attribute of food,which is an important factor to trigger consumers'appetite.The flavor of food was influenced by the origin of raw-materials and processing methods.In order to transform the advantages of local aquatic raw materials into product advantages,the smell and taste of five dominant aquatic raw materials in Guangxi were studied before and after frying,including Pinctada Martensii-PM,Procypris Merus-PC,Nemipterus Virgatus-NV,Tilapia-TP,Litopenaeus Vannamei-LV.The similarities and differences between them were explored.Their key flavors were identified.Their fried products were characterized by flavor identification.The main chemical composition changes of five aquatic raw materials before and after frying were analyzed.This study was expected to provide a theoretical basis for the deep processing of related aquatic raw materials and product development.The research contents and results were as follows:Five kinds of aquatic raw materials were detected to have heavy fishy smell.Inorganic sulfide,aromatic and methyl compounds were the main odors.GC-IMS analysis showed that alcohols,aldehydes and ketones were the differences among the five aquatic raw materials.A total of 57 compounds were identified by GC-MS.31,24,28,20 and 13 compounds were identified in PM,PC,NV,TP and LV,respectively.Aldehydes and alcohols were the main key flavor components,namely 1-octen-3-ol and nonanal,with mushroom,fishy and fruity flavor.Umami and sweetness were prominent among the five ingredients.The total amount of free amino acids and flavorful nucleotides were significantly different.Good umami and sweet flavors were represented by umami and sweet amino acids.Umami was directly contributed by IMP.The taste of aquatic raw materials was enhanced by lactic acid,malic acid and succinic acid.The contribution of flavor was provided by K⁺.The auxiliary flavor-enhancing effect was provided by Na⁺.Five raw materials were found to have a heavy grease flavor after frying.Inorganic sulfides,methyl groups,organic sulfides and nitrogen oxides constitute the main odors.GC-IMS results showed that alcohols and ketones were the difference after fried aquatic products.A total of 62 volatile components were identified by GC-MS.45,29,38,36 and 29 compounds were identified from PM,PC,NV,TP and LV,respectively.1-octen-3-ol,2-methylpropanal,2-methylbutanal,3-methylbutanal,(E,E)-2,4-decadienal,2,3,5-trimethylpyrazine,2-ethyl-3,6-dimethylpyrazine,and 2-ethyl-3,5-dimethy-lpyrazine were identified as eight key flavor ingredients.By GC-O-MS analysised,18,16,19,19 and 15 characteristic flavor components were identified from PM,PC,NV,TP and LV,respectively.Good umami and sweet flavors were present in five aquatic fried products.Good umami and sweet flavors were provided by umami and sweet amino acids.Significant differences were found in AMP and IMP content,which contribute to umami taste.Lactic acid,malic acid,succinic acid,K⁺and Na⁺were found to contribute to taste.Good smell and taste were expressed in fried aquatic products.Compared the chemical composition of five raw materials before and after frying,the results showed that V_Awas detected only in PM,PC and NV in fresh samples.The content of V_Ein V_B1and PM of NV was found to be relatively high.V_Awas detected only in PM after frying.The content of V_Ein VB1 and PM of PC was found to be relatively high.The contents of glycogen and soluble sugar in PM were the highest before and after frying.The content of salt-soluble protein in PM,PC,TP and LV muscle was relatively higher in fresh samples.The content of salt insoluble protein was the highest in NV.The soluble protein content was LV>PC>TP>PM>NV.The content of salt-insoluble protein in the fried samples was proved to be the highest.The percentage of soluble protein was found to decrease.In conclusion,the flavor of aquatic products before and after frying can be provided by the degradation and interaction among vitamin,glycogen and soluble sugar,protein and soluble protein.The results showed that the flavor difference existed in the five ingredients.Among them,the difference between PM meat and other raw materials was significant.Umami,sweet and fishy taste were considered as the typical flavor characteristics of five aquatic raw materials.Their flavor was preserved after frying.The smell changed from fishy(1-octen-3-ol)to oily and nutty(aldehydes,pyrazines).Odor transformation was found to be related to the degradation and interaction of glycogen and soluble protein.Therefore,the flavor of aquatic products can be improved by selecting suitable raw materials and controlling processing conditions.