Effect Of Boiling Technology On Flavor And Texture Of Beer Fish And Its Mechanism Study

Beer Fish(boiled fish with beer)is a famous local specialty in Yangshuo,China.The fish is tender,spicy and rich in beer flavor.However,there are no research reports on the process of beer fish products suitable for industrialized production,and the non-standardized processing technology affects the quality stability of the products and the repeatability of processing operations.Therefore,optimization of beer fish processing technology has important meaning to quality control and standardized evaluation in the industrial production of beer fish.In this study,tilapia was used as raw material to study the influence of the boiling technology on the quality of beer fish during the production process.The boiling conditions were optimized through fuzzy mathematics sensory evaluation combined with response surface methodology.And from the perspective of gel properties and molecular structure of myofibrillar protein,the influence mechanism of beer on the flavor and texture characteristics of fish during the cooking process was explored.The main conclusions are as follows:(1)The beer additive amount,boiling time and heating power had obvious effects on the flavor and texture characteristics of fish,while the solid-liquid ratio had little.With the increase of beer additive amount,the signal intensity of fishy odor compounds such as hexanal,heptanal,octanal decreased,while that of alcohol odor compounds such as ethanol,ethyl acetate,2-butanone increased.The hardness and chewability of fish decreased firstly and then increased,while the elasticity was firstly increased and then decreased.With the prolongation of boiling time,the signal intensity of octanal,2-ethyl hexanol and benzaldehyde in fish decreased.The hardness and chewability increased first and then decreased,reaching the lowest value at 30 min,and no significant change occurred after that.With the increase of heating power,the signal intensity of isopropyl acetate,2-acetone and 1-butanol was firstly decreased and then increased while 2-butanone increased continuously.The hardness,chewability and elasticity of fish decreased first and then increased,and the hardness and chewability were the lowest when the heating power was 1000 W,and then began to increase with increasing heating power.(2)In the fuzzy mathematical sensory comprehensive evaluation method of beer fish,the weight order of sensory factors was taste > tenderness > odor >tissue state > elasticity.Response surface optimization test was used to optimize the brewing conditions of beer fish.The optimum technological parameters were obtained as follows: beer additive amount was 66%,boiling time was 33 min,heating power was 500 W.Under these conditions,the comprehensive evaluation value of beer fish was 7.91.The beer additive amount and the boiling time significantly affects the sensory quality of beer fish,and can be used as processing control key points in the industrial production of beer fish.The hexanal,heptanal and other fishy compounds decreased after the optimized cooking process,and the fish contained ethanol,2,3-pentanedione,ethyl acetate and other beer-flavor substances.The decrease of fish hardness,machinability and p H indicates that beer can remove fishy odor and change meat quality.The fish texture and sensory comprehensive evaluation value of the beer fish made by optimized method was higher than that of the traditional method.(3)Mechanism study of beer’s effect on flavor and texture of fish.Tilapia myofibrillar protein(TMP)was mixed with beer and heated for 30 min.Results showed that with the beer additive amount increased from 10% to 50%,turbidity increased significantly,and the gel hardness firstly decreased,reaching the lowest value then increased.Both finally showed a steady trend when beer additive amount exceeded 50%.the gel morphology was porous with 30% beer additive amount.And increasing the beer additive amount to 60% could increase the number of protein cross-connections,decrease the pores,and make the chain structure thinner.Compared to the control,the VOCs composition of TMP gel was significantly increased by a variety of compounds,including alcohols,ketones and esters,such as ethanol,butanone and ethyl acetate.At the same time,the signal intensity of some original compounds in TMP gel was significantly reduced,such as hexanal,heptanal and octanal.With the augment of beer additive amount,the signal intensity of methyl acetate,ethyl propionate,ethyl butyrate and other compounds continued to increase,and there was an obvious increase when beer additive amount was 30% and 60%.The signal intensity of 2-pentanone increased first and reached the highest value at 30% and then decreased.The signal intensity of hexanal et al.decreased and almost disappeared after 60%.The adsorption capacity of TMP treated with 60% beer additive amount on ethanol,2,3-pentanedione increased,while on hexanal and heptanal decreased.The molecular structure of TMP was changed by beer binding heat treatment,and the surface hydrophobicity and carbonyl content were significantly increased with the increase of beer additive amount.The reactive sulfhydryl group content increased firstly and reached the highest value when beer additive amount was 30%,and then decreased.The content of the total sulfhydryl group increased first with the increase of beer content,then began to decrease when the beer content exceeded50%,and finally leveled off.The relative content of α-helix decreased,while the content of β-turn and random coil increased.By acting on myofibrillar protein molecules,beer expanded the molecular structure and transformed the spatial conformation,resulting in enhanced surface hydrophobicity and increased groups exposure,which changed the gel structure and the volatile compounds adsorption capacity,thus affected the flavor and texture quality of fish.