| In this study,Pollock bone was taken as the research object,and how to improve the quality of fish bone condiment was systematically studied.The Pollock was utilized by one extraction and two enzymatic hydrolysis.The purpose was to explore how to reduce the bitterness of the condiment and enhance the flavor of the product.(1)The Pollock bone was first boiled,and the process of atmospheric pressure boiling and high atmospheric pressure boiling was optimized.Through two single factor experiments and comprehensive reality,the optimum process of Pollock bone broth was determined as follows:the ratio of material to water was 1:2,the boiling temperature was 100 ~oC,and the boiling time was 3 h.Under this condition,the protein dissolution rate was 5.81 g/(100 g fish bone).Through orthogonal experiment,the three factors of material-water ratio,time and temperature in the process of high pressure boiling were optimized,and the optimum conditions were obtained as follows:material-water ratio 2:1,temperature 110 ~oC and time 2 h.The protein dissolution rate of broth cooked at high atmospheric pressure was 1.54 times that of broth cooked at atmospheric pressure,the polypeptide content was 1.20 times that of broth cooked at atmospheric pressure,and the content of 5'-AMP in flavor nucleotides was 4.87 times that of broth cooked at atmospheric pressure.31 and 37 kinds of volatile flavor substances were detected in broth of fish bones prepared under atmospheric pressure and high atmospheric pressure respectively.The volatile flavor substances of broth of fish bones prepared under atmospheric pressure were richer than that of broth of fish bones prepared under atmospheric pressure.At the same time,more aldehydes and ketones were produced under high pressure,which had better flavor.(2)Fish were determined at 15,30,45,60,75,90,105 and 120 min.After 30 min,the polypeptide began to dissolve steadily,and finally stabilized at 2.00 mg/L.The concentration of three flavoring nucleotides reached the highest in the range of 90-105 min.The lactic acid content of organic acid flavor substances reached the highest level of 67.91 mg/L in 90 min.The continuous high temperature environment would degrade the acid or react with the dissolved volatile alcohols to form esters.Aldehydes and ketones are the main components of the flavor of fish bone soup.With the increase of thermal reaction time,furans increase.Alcohols and acids also produce esters in the reaction process,which further improves the flavor of fish broth at high atmospheric pressure.(3)This chapter was to determine the effect of ultra-high pressure processing(UHP)coupled with enzymatic hydrolysis on the flavour compounds of Alaska pollock frame(APF)hydrolysates.The optimal conditions of the UHP enzymatic hydrolysis were obtained by orthogonal experiments,and then free amino acids,nucleotide and volatile flavour components in atmospheric pressure and UHP of hydrolysates were analyzed.The results indicated that the optimal conditions for UHP enzymatic hydrolysis were as follows:pressure time was 60 min,pH value was 7.5,and pressure was 150 MPa.The amino acid nitrogen and degree of hydrolysis of the hydrolysates were separately 0.380 g/100 mL and 41.62%under the optimum values.The total free amino acid(except Trp and Met)and delicious amino acid(DAA)content of atmospheric pressure and UHP hydrolysates were 5 528,2145 mg/100 g vs 6 234,2411 mg/100g respectively,increased by 12.77%and 12.40%.Compared with atmospheric pressure hydrolysates,UHP treatment showed significantly higher levels of 5'-IMP(P<0.05).The major compounds included 4 kinds of acids(45.73%),5 kinds of aldehydes(6.71%),2 kinds of esters(0.38%)and one kind of amines(0.14%)in the enzymatic hydrolysates of atmospheric pressure.While in the enzymatic hydrolysates of UHP included 7 kinds of Ketones(18.31%),8 kinds of aldehydes(6.35%),3 kinds of alcohols(2.61%),one kind of esters(0.38%)and one kind of furans(7.89%).In conclusion,UHP enzymatic hydrolysis can be a potential tool to improve the flavour compounds of hydrolysates.(4)The orthogonal experiment was carried out to optimize the three factors of time,dosage and proportion(Protamex:Flavorzyme).The optimum conditions were enzymatic hydrolysis for3 h,Protamex:Flavorzyme=2.5:1,total dosage of double enzymes 0.70%.The hydrolysis degree and amino acid nitrogen content were the highest,27.26%and 0.29 g/100 mL,respectively.At the same time,bitterness,astringency and bitter aftertaste were the lowest,the taste was basically the same as other groups,and kokumi was improved.It was concluded that double enzymatic hydrolysis could effectively reduce the bad flavor of enzymatic hydrolysate without reducing the degree of hydrolysis.Thirty-one kinds of volatile flavor compounds were detected in the enzymatic hydrolysate,mainly composed of hydrocarbons,aldehydes,ketones,esters,acids,amines,alcohols,pyrazines and furans(5)The conditions of emulsification and enzymatic hydrolysis were as follows:the amount of alkaline protease added was 0.4%,maltodextrin:beta-cyclodextrin=1:2,the total amount added was 15%,and the enzymatic hydrolysis time was 3 h.17 kinds of free amino acids were detected,the total free amino acids were 104.70 mg/100 g,and essential amino acids accounted for 50.12%of the total free amino acids.Under the same bitter conditions,the polypeptide in the hydrolysate of emulsifying enzyme was 1.20 times as much as that in the atmospheric fish bone soup.A large number of 5'-GMP,5'-IMP and 5'-AMP were released from the hydrolysate of emulsifying enzyme,and the content of 5'-AMP was 3.80 times as much as that of the atmospheric fish bone soup.Thirty-one volatile flavor compounds were detected in the atmospheric fish bone soup,while only 21 compounds were detected in the emulsifying enzyme hydrolysate,which may be due to the masking and embedding of some flavors by maltodextrin and beta-cyclodextrin. |
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