Research On Flavor Of Breeding Large Yellow Croaker And Wild Large Yellow Croaker

Pseudosciaena crocea, commonly known as large yellow croaker, are popular due to its delicious meat and charming apperance. It belongs to order Percifonnes and family Sciaenidae. Nowadays, large yellow croakers become one of the largest scale cultured marine fish in China. However, due to its high fat content, heavy fish smell and poor taste, people's awareness of large yellow croaker is negatively influenced, which makes it difficult to be produced by industiy. This study aims to compare the cultured large yellow croaker with wild large yellow croaker through systematically analysis of the volatile substances. In order to provide a theoretical basis for improving its flavor and taste and relating products. Meanwhile, it will also promote the development of the deep processing of large yellow croaker to satisfy people's increasing demand for the quality of life.Firstly, we analyzed the flavor of cultured large yellow croaker and related factors under different boiling condition by the fuzzy mathematics method. The optimum condition was boilling the fish5min in100℃water, which will extract the flavor substance well.The single factor experiment and the quadratic regression rotating combination test were designed to optimize the condition of extraction fiber, GC procedures, head of solid phase micro-extraction and other conditions. The optimum conditions were:5g sample,5%NaCl,6℃/min GC warming rate, DVB/CAR/PDMS fiber was selected, and the extract temperature was75℃, the extract time was35min, the incubation time was20min, and the desorb time was5min. Under this condition, the volatile flavor substances of cultured large yellow croaker and wild large yellow croaker were extracted and isolated. Meanwhile, the results were determined with combined mass spectrometry and retention indices. Combining with odor threshold, the relative odor activity value (ROAV) was applied to confirm the key odor compounds. The results indicated that the key odor compounds (ROAV>1) of cultured large yellow croaker were composed of Nonanal, Octanal, Hexanal, Heptanal,(Z)-4-Heptenal,1-Octen-3-ol, ethyl acetate, Pentanal,(E,E)-2, and so on., and the key odor compounds (ROAV>1) of wild large yellow croaker were composed of (E)-2-Octenal, Nonanal, Trimethylamine, Octanal, Hexanal,2-methyl butyl aldehyde, ethyl acetate,3-methyl butyl aldehyde, Decanal, Heptanal,(E,E)-2,4-Heptadienal,1-Octen-3-ol, Phenylglyoxylic, limonene,2-methyl propanal and so on. Secondly, effect of the five extracting solvents on water-soluble sapidity materials extraction were compared, including hot water, cold water,80%ethanol extraction, ultrasonic-PCA and hot-ethanol. The results showed that the method of hot water extraction was best, the extiaction rate [(total nitrogen in extraction/total nitrogen in raw material) X100%] was22.90%. Based on this, non-volatile flavor substances of the cultured large yellow croaker and wild large yellow croaker were analysed systematically, including free amino acids, water-soluble short peptide, ATP and the associated contents:TMAO, glycine betaine, organic acid, inorganic ions. Meanwhile, the order of the contribution of free amino acids on the taste of cultured large yellow croaker was concluded in this paper through analyzing the contents and the strength of the taste compounds, the order was:Arg (1.32)> His (0.77)> Lys (0.73)> Glu (0.55)> Gly (0.21)> Ala(0.18), and the order of the free amino acids contribution on the taste of wild large yellow croaker was: Arg(2.26)> Glu(0.47)>His (0.31)> Ala (0.28)> Gly(0.21)> Met(0.18)> Lys(0.15), the rest were less than0.15, behaving coordination function. The total amino acids content in the form of water-soluble peptide in cultured large yellow croaker were only73.65mg/100g, while that of wild large yellow croaker were130.01mg/100g. IMP,AMP,GMP, TMAO and glycine betaine had important contribution on the taste of large yellow croaker. Succinic acid may be one of the important factors formed the main taste. The sapidity strength of K+was greater than1, which was the main sapidity ion, and the Na and Cl-ions were important also. Finally, the umami synergy analysis of the main sapidity free amino acids and nucleotide materials showed that the cultured Large Yellow Croaker's monosodium glutamate equivalent (EUC) was as high as13.43MSG/100g, and the sapidity strength value was447.67? while the wild large yellow croaker's EUC was as high as9.12MSG/100g, and the sapidity strength value was304, all of these were benefit from the high content of IMP, which also explained the well taste of large yellow-croaker.Finally, the representative flavor substances of cultured large yellow croaker and wild large yellow croaker were compared and researched deeply by the method of three points in the reduction of experiment and add tests. And then the characteristic flavor substances of the cultured large yellow croaker were conformed, which were Glu, Ala, Lys, Arg, Cys, AMP, IMP, TMAO, K+Na+, Cl'and glycine betame, while the wild large yellow croaker's were Ser, Pro, Lys, Glu, Gly Arg, Cys, AMP, and IMP, TMAO, K+, Na+, Cl-and glycine betaine. Sensory evaluation and electronic tongue data showed that the characteristic flavor compounds confirmed the former data as well. It provided a theoretical basis to improve the flavor of cultured large yellow croaker and its products.