Analysis And Removal Technology Of Fishy Odor In Meat And Oil Of Giant Salamander (Andrias Davidianus)

In order to promote the processing and utilization of cultured giant salamanders,the odor components and removal methods of meat and oil of giant salamanders were studied.Volatile substances in meat,claw and skin of giant salamander were analyzed by solid phase microextraction-gas chromatography-mass spectrometry.The main types and characteristic components of fishy smell were determined.Combined with sensory evaluation,qualitative and quantitative detection methods of fishy smell of giant salamander were established.Using betacyclodextrin,ethanol,tea polyphenols,yeast and vacuum heating to remove the fishy smell of salamander meat and oil,the optimum deodorization methods and conditions were selected.The fishy smell of salamander meat and oil was greatly reduced,and the purpose of deodorization was achieved.The main results are as follows:(1)Study on the characteristic substances of giant salamander’s fishy smell.The fishy odor of different parts of giant salamander is characterized by fishy odor and earthy odor.The volatile components in different parts of giant salamander were analyzed and identified by headspace solid phase microextraction coupled with gas chromatography-mass spectrometry.57 species,69 species and 49 species were identified from the flesh,claw and skin of giant salamander,of which 15 were the same volatile components.These volatile substances include aldehydes,ketones,alcohols,hydrocarbons and acids.According to the judgement,nonanal,octanaldehyde,decanal,heptaldehyde,hexanal,undecanaldehyde and 1-octene-3-alcohol are the main substances of salamander odor.There are 60 volatile substances in the oil of giant salamander.Before deodorization,the main odor substances of giant salamander oil are heptaldehyde,2,4-heptadienal,2-octenaldehyde,nonanal,2,4-nonadiene aldehyde,2,6-nonadienealdehyde,2-decanoaldehyde,2,4-decadienal(EE),2-ethyl-1-hexanol.Octanal,sebaceous aldehyde,hexanal and undecannaldehyde have not been identified.The odor characteristics are fishy and greasy.(2)Deodorization technology and evaluation of giant salamander meat.The deodorization of giant salamander meat was carried out by using the methods of β-CD embedding,ethanol extraction,tea polyphenols antioxidant and yeast fermentation respectively.The deodorization process was optimized by orthogonal test at 50 C and 0.08 MPa for 30 min.The sensory evaluation results were combined with the total concentration of nonanal,octanal,decanal,hexanal and undecanaldehyde.The results showed that yeast fermentation treatment was effective for deodorization of salamander meat.The deodorization effect was the best,followed by tea polyphenols.The deodorization conditions of yeast were 1.5% yeast,30 C and 30 min.After yeast fermentation,the meat of giant salamander had the lowest concentration of odorous substances,showing a light yeast flavor.The meat of giant salamander deodorized by yeast was detected by GC-MS,and the original 57 volatile ingredients were changed into 68 volatile substances.The relative contents of aldehydes and amines decreased after deodorization of salamander meat.Octanaldehyde and hexanal were not detected.Amines were only 0.07%,alcohols(20.26%)and esters(38.59%)had the highest relative content.The total concentration of five odorous substances was 3.17 g/100 g.The meat quality of salamander deodorized by four methods was not affected,which ensured the quality and safety of salamander meat.(3)Deodorization and volatile components analysis of giant salamander oil.Tea polyphenol solution,yeast solution,tea polyphenol-yeast complex solution and activated carbon can remove the fishy smell of giant salamander oil in varying degrees after refining.Among them,tea polyphenol-yeast complex solution has better deodorization effect,and the oily smell after deodorization is smaller.The deodorized giant salamander oil contains 11 known fatty acids,20.6% saturated fatty acids,49.1% monounsaturated fatty acids,33.9% oleic acid,13.7% polyunsaturated fatty acids,6.6% linolenic acid,2.8% EPA and 3.9% DHA,respectively.There were still 60 kinds of volatile substances before and after deodorization of tea polyphenol-yeast complex solution,and the relative content of volatile substances changed obviously.Before and after deodorization,17 aldehydes(14.84%,9.16%),4 alcohols(6.00%,7.99%),2 ketones(2.56%,1.13%),4 esters(2.94%,0.63%),2 acids(0.14%,0.18%),28 hydrocarbons(67.77%,15.77%)and 3 other compounds(6.35%,64.35%)were identified by GC-MS and analyzed by ROVA(>0.1).The main characteristic substances are benzaldehyde,phenylacetaldehyde,2-nonylaldehyde,2,4-decene aldehyde(ZZ),1-octene-3-alcohol,linalool,alpha-pinene,beta-pinene and naphthalene,with nutty,hyacinth,mushroom and oil aroma.The meat of giant salamander was deodorized by yeast fermentation broth and vacuum.The smell of meat of giant salamander was greatly reduced,and the quality and quality of meat did not change significantly,which laid a foundation for meat consumption and processing of other products.The oil of giant salamander can not smell the odor after deodorizing with compound deodorization,but presents the fragrance of oil.