Study Of The Correlative Components Of Fishy Odor In Carassius Auratus And Sparuslatus And The Effect Of Heat Treatment

The fishy odor is one of the key factors affecting the processing and marketing of fish and other aquatic products.Freshwater carassius auratus and sea fish sparuslatus are the representative raw materials for the processing of traditional fish soup in China.In thesis paper,the main volatile substances in fish body were detected and analyzed by sensory evaluation and gas chromatography-mass spectrometry(GC-MS-O)technology to determine the fishy odor related components in fish body.Aroma recombination,and omission experiments were used to verify the results.Finally,the effects of storage time and heat treatment on the fishy odor related components after slaughter were preliminarily discussed.The main research results are as follows:1.By GC-MS qualitative and quantitative analysis,33 and 32 volatile compounds were identified in fresh carassius auratus and sparuslatus respectively,with a total of 37 compounds.Among them,there are 17 kinds of aldehydes,8 kinds of alcohols,6 kinds of hydrocarbons,2 kinds of ketones,2 kinds of aromatic compounds and 2 others.The total volatile components contents of carassius auratus and sparuslatus were 674.40 ?g/kg and 1315.19 ?g/kg,respectively.The contents of aldehydes(290.08 ?g/kg),alcohols(144.57 ?g/kg)and ketones(116.95 ?g/kg)in the volatile compounds of carassius auratus were relatively high,while the contents of aldehydes(217.27 ?g/kg)and hydrocarbons(881.20 ?g/kg)in the sparuslatus were relatively high.The sensory evaluation results showed that the flavor attributes of carassius auratus and sparuslatus were basically similar,mainly flavor presenting fat and grass,but grass and earthy flavor of carassius auratus were more obvious than that of sparuslatus.2.GC-MS-0 analysis showed that there were nine fishy odor associated components in carassius auratus and sparuslatus,which were 1-octen-3-ol,nonanal,decanal,(E,E)-2,4-nonadienal,(E,E)-2,4-dodecadienal,(E,E)-2,4-decadienal,dodecal,(E,Z)-2,6-nonadienal and hexanal.In particular,2-methylisoborneol(2-MIB),one of the representative substances of earthen odor,was identified in carassius auratus samples.According to OAV analysis,the key odour substances(OAV? 1)of carassius auratus and sparuslatus were 16 and 17,respectively.By GC-MS-O and OAV analysis,the key fishy odor associated components in carassius auratus and sparuslatus were identified as(E,Z)-2,6-nonadienal,(E,E)-2,4-decadienal,nonanal,(E,E)-2,4-nonadienal,hexanal and 1-octen-3-ol.The key fishy odor associated compounds in carassius auratus and sparuslatus were verified by aroma recombination and omission experiments.The results showed that the key fishy odor associated components of carassius auratus were(E,Z)-2,6-nonadienal,nonanal,hexanal,(E,E)-2,4-decadienal,(E,E)-2,4-nonadienal and 1-octen-3-ol.The key fishy odor associated components in sparuslatus include(E,Z)-2,6-nonadienal,nonanal,(E,E)-2,4-decadienal and(E,E)-2,4-nonadienal.3.Within 12 h at 4? after slaughter,the fishy odor components represented by hexanal,1-octen-3-ol and nonanal showed a trend of increasing.Carassius auratus was more likely to produce aldehyde volatile compounds than sparuslatus,but dimethylamine in sparuslatus was more likely to produce in later stage.The indexes such as peroxidevalue(POV),thiobarbituric acid value(TBARS)and lipoxygenase(LOX)showed that carassius auratus was more prone to lipid oxidation than sparuslatus,and the content of fishy substances was positively correlated with the degree of lipid oxidation.Direct cooking of fish can significantly change the content of aldehyde fishy odor substances in fish.The content of hexanal,nonanal,octanal,E-2-decenal,(E,E)-2,4-heptadienal,(E,E)-2,4-decadienal,(E,E)-2,4-dodecadienal and other fishy odor substances increases after cooking,but dodecanal and(E,Z)-2,6-nonadienal were not detected after boiling.However,after frying and boiling,hexanal,(E,Z)-2,6-nonadienal,dodecanal,decanal and other fishy odor substances were reduced.Specially,1-octen-3-ol did not change much before and after heat treatment,and it was difficult to remove the fishy substances in boiling and frying.Fried will produce high content of 2,3,5-trimethylpyrazine,3-ethyl-2,5-dimethyl-pyrazine,E-2-methyl-6-(1-propenyl)-pyrazine with baking flavor pyrazine compounds,carassius auratus is more obvious than sparuslatus.Boiled after frying will greatly reduce the content of pyrazines.