Study On The Activity And Flavor Of Fish Sauce During Fermentation

Fish sauce is a common condiment in coastal areas of China.Flavor is an important attribute of condiments.Although its content is small,it is an important quality characteristic that distinguishes the flavors of two kinds of foods.Due to the different fermentation materials and fermentation processes of fish sauce,the flavor of fish sauce will vary.In this study,the physical and chemical components and flavor components of the fish sauce fermentatio n process were measured.At the same time,the volatile flavor substances of different aquatic products were also studied.The conclusions are as follows:?1?Comparison of physical and chemical components of grass carp and carp visceral fermented fish sauceTaking grass carp fish sauce and carp fish sauce as research objects,the changes of physicochemical components?TVB-N,AA-N,pH,NaCl,fat,total sugar,etc.?in the fermentation process of fish sauce were stu died,and the octopamine in the fermentation process was determined.And changes in the content of taurine.During the fermentation process,the pH value decreased,and the fish sauce of eel was slightly higher than that of grass carp.AA-N increased first and then decreased slightly,and the content of eel sauce was higher than that of grass carp sauce.TVB-N increased first and then tended to be stable.The content of eel sauce was slightly higher than that of grass carp sauce.NaCl increased slightly,but there was no significant difference between grass carp sauce and eel sauce.The fat content showed a decreasing trend,and the difference between grass carp fish sauce and eel fish sauce was not significant.The content of total sugar increased first and then decreased,and the content of grass carp fish sauce was higher than that of eel fish sauce.HPLC method for determination of octopamine and taurine was established.2,4-dinitrofluorobenzene was used as a pre-column derivatization reagent,and the mobile phase was acetonitrile:0.02 mol/L sodium d ihydrogen phosphate solution?40:60?at pH 7.5,a flow rate of 1 mL/min,and a detection wavelength of 360 nm.The correlation coefficient of the standard curve of octopamine was R²=0.9926,and the recovery was 99.23%.The correlation coefficient of the standard curve of taurine was R²=0.9929,and the recovery was 97.67%.The method can be used for determining the content of octopamine and taurine in fish sauce.During the fermentation,the content of octopamine increased,but the content of taurine did not change.The content of octopamine in fermented fish sauce was 6.53±0.12 mg/mL,octopamine in eel sauce was 7.49±0.08 mg/mL,taurine in grass fish sauce was14.29±0.38 mg/mL and taurine in eel sauce was 1.21±0.24 mg/mL.?2?Study on Optimization of Extraction Process of Volatile Flavor Extracts from Fish Sauce by Response Surface MethodologyBased on the number of peaks and peak volume,the response surface optimization experiment was used to determine the optimal conditions for the extraction of volatile flavors from fish sauce:extraction temperature 57°C,extraction time 70 min,oscillation frequency 510 r/min,under this condition,the maximum number of peaks predicted by the model is 1558.55,and the peak volume is 7.56×10¹⁰.The volatile flavor substances were detected in the silverfish fish sauce samples under the optimal extraction conditions.A total of 152 compounds were detected and classified.The most abundant compounds were alcohols and esters,which were 26.02%and 25.91%,respectively.?3?Changes in volatile flavors during the fermentation of fish sauceThe static headspace solid phase microextraction?HS-SPME?combined with full two-dimensional gas chromatography mass spectrometry?GC×GC-MS?was used to analyze the changes of volatile compounds in the fermentation process.Samples with different fermentation time points were taken for comparison.The compounds with obvious changes during fermentation were selected for comparison.The 116 compounds were detected and classified,and combined with mass spectrometry database and retention index.Initial identification.On the basis of this,Principal Component Analysis?PCA?and heat map were used to analyze the variation of volatile compounds.The results showed that the flavor of fish sauce could be clearly distinguished after 20 days of fermentation,indicating the flavor compound of fish sauce.The production is mainly in the late stage of fermentation.?4?Study on volatile flavor substances of different aquatic productsThe volatile flavor compounds of fish sauces from 6 different aquatic products were determined.The order of concentration of volatile compounds was:Eel fish sauce>carp fish sauce>anchovy fish sauce>grass carp fish sauce>fresh fish sauce>silver fish Fish sauce.The maximum number of compounds detected in carp fish sauce is 178,and the minimum number of fish fish sauce is 54.Classification studies have found that alcohol,esters and acid compounds account for the largest proportion.Based on this analysis,fresh fish,squid and anchovy fish sauce were not distinguished by PCA and heat map analysis.The composition and content of volatile flavor compounds were similar;grass carp,silver carp and silver fish fish sauce were good areas.Separately,the volatile compound s in the fish sauce are significantly different from the others.At the same time,the content of free amino acids in the fish sauce samples was determined,and the glutamic acid content in the fresh fish fish sauce was found to be very high,mainly because a certain amount of sodium glutamate was added during the fermentation to enhance the umami taste..The bitter amino acids in grass carp fish sauce and anchovy fish sauce are relatively high,and the content of sweet amino acids in carp fish sauce,silver fish fish sauce and carp fish sauce is the highest,which is consistent with sensory evaluation results.