Study On Deodorization Of Capelin By Organic Acid

Capelin has high nutritional value and it contains proteins,lipids,vitamins and other nutrients.However,the fishy smell of capelin is very prominent,which restricts the development of capelin industry.The objective of this study was to use capelin as a raw material.The composition of the volatile compounds in the edible parts of capelin were analyzed by the volatile compositions based on the odor contributions of volatile compounds.On this basis,organic acids was used to deodorize the raw materials,aiming to provide theoretical guidance for the capelin.The main research contents and results were as follows:(1)Analysis of the fishy substances of capelin.Through detecting volatile compounds of capelin by solid-phase microextraction(SPME)combined with gas chromatography-mass spectrometry(GC-MS),24 effective volatile substances were detected,which contains 10 different kinds of aldehydes,7 different kinds of hydrocabons,2 different kinds of ketones,2 different kinds of alcohols and 3 others of other compounds;The most abundant substances were 3,5,5-trimethyl-2-hexene and 2,7-octadien-1-ol.With the analysis of odor contribution value,it was concluded that the main odor characteristics of capelin were mainly cucumber-like fragrance,combined with a small amount of fishy,oily,grassy scent,and the earthy smell.Combined with the odor characteristics of the volatile substances,the main fishy substances were identified as 1-octene-3-ol,nonaldehyde,E,Z-2,6-nonadienal,Z,Z-3,6-nonadienal,octanal,heptanal,hexanal,2-vinylaldehyde,E,E-2,4-heptadienal,Z-4-heptadienal,trimethylamine and 3,5-octadiene-2-ketone.(2)To study the condition of capelin deodorization.A variety of food-grade organic acids(citric acid,ascorbic acid,acetic acid,malic acid and lactic acid)were used to deodorize the capelin,and the sensory evaluation and trimethylamine content were also adopted as evaluation indicators in this process.Through single-factor test and orthogonal experiment,the best conditions for each organic acids was clarified,the best condition for citric acid was that 1.5% of citric acid was soaked for 15 ABSTRACT minutes,under the temperature of 15℃,after this processed,capelin contained10.58μg/m L trimethylamine,and the sense evaluation value was 1.63;By contrast,the best condition for ascorbic acid was that 2.5% of acetic acid was soaked for 15 minutes,under the temperature of 15℃,after this processed,capelin contained 12.14μg/m L trimethylamine,and the sense evaluation value was 2.63;the best condition for acetic acid was that 3% of acetic acid was soaked for 20 minutes,under the temperature of 15℃,after this processed,capelin contained 12.38 μg/m L trimethylamine,and the sense evaluation value was 2.88;the best condition for malic acid was that 2.5% of malic acid was soaked for 25 minutes,under the temperature of 15℃,after this processed,capelin contained 11.82 μg/m L trimethylamine,and the sense evaluation value was 2.51;the best condition for lactic acid was that 2% of lactic acid was soaked for 15 minutes,under the temperature of 15℃,after this processed,capelin contained 11.31 μg/m L trimethylamine,and the sense evaluation value was 2.02.(3)To explore the deodorization quality of capelin.Under the best process conditions,sensory evaluation,protein content,volatile basic nitrogen content,and thiobarbituric acid value being quality indicators,it was found that 1.5%-2.5%organic acids could not only inhibit the oxidation of proteins and fats,but also could remove the offensive odor.Comparing the best treatment conditions of each organic acid,it was comprehensively considered that the pleated fish treated with 1.5% citric acid at 15 ℃ for 15 minutes had the best quality and the most obvious deodorization effect.A total of 139 volatile substances were detected before treatment and 147 after treatment by two-dimensional gas chromatography-time-of-flight mass spectrometer.Thirty-one characteristic flavor compounds were identified based on their odor contribution values,among which E,Z-2,6-nonadienal,butyral,E-2-nonenal,E-2-octenal,nonal,2-ethyl furan and 2-undecanone were higher than1000.After organic acid treatment,1-pentene-3-ol,phenylacetaldehyde,benzyl alcohol,(E,E)3,5-octene-2-one,trimethylamine,e-2-pentenal and other fishy substances content were significantly reduced.