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Study On The Changes And Control Technology Of Biogenic Amines Contents In Fish Protein Hydrolysate

Posted on:2016-04-15Degree:MasterType:Thesis
Country:ChinaCandidate:M T QiuFull Text:PDF
GTID:2381330482467892Subject:Food processing and security
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Fish muscle is an excellent source of nutritive and easily digestible proteins.Over millions tons of fish are harvested each year in China.However,in recent years,the proportion of quality marine fish stocks are declining while that of under-utilized fish species are increasing,in the meanwhile,many fish processing by-products are produced during fish processing.These low-value resources with negligible market value are extremely perishable and considerable amounts of them are discarded each year.Hydrolysis processes can convert these low value resources into marketable and acceptable forms known as fish protein hydrolysate,which rich in free amino acids and peptides.Nevertheless,due to the high content of free amino acids,biogenic amines can be easily produced in these hydrolysates during processing and transporting,by the decarboxylase enzyme produced by microorganism.Some toxicological characteristics and outbreaks of food poisoning are associated with biogenic amines.Up to now,studies on the controlling of biogenic amines accumulation in fish protein hydrolysate are still scarce.A better knowledge of the biogenic amines controlling technology is necessary to improve the quality and safety of fish protein hydrolysates.In the present study,changes in biogenic amines contents during enzymolysis process of fish protein were investigated,and removal of biogenic amines in fish protein hydrolysate by electrodialysis technology was carried out.The results were as follows:(1)With biogenic amines contents as the index,an enzymatic hydrolysis screening experiment was done for neutral protease,trypsin and papain,respectively.With the increase of hydrolysis time,biogenic amines contents in the hydrolyzates increased gradually.And the fish protein hydrolysate hydrolyzed by trypsin contained the lowest contents of putrescine,cadaverine,histamine and tyramine.With a pH value of 8 and temperature at 50?,the protein hydrolysate of trypsin had lower biogenic amines contents,higher degree of hydrolysis and higher recovery rate of nitrogen.(2)The effects of electrodialysis on the removal of biogenic amines in mackerel hydrolyzate were studied.Results showed that electrodialysis could decrease the contents of biogenic amines,accompanied with the loss of AAN.pH value affected the removal rate of histamine and the loss of AAN.When pH ranged 2 to 5.5,the removal rate of biogenic amines increased with the increase of pH value.When pH>5.5,putrescine and cadaverine remained constant while histamine and tyramine decreased sharply.The lowest loss of AAN was got when the pH value was 7.(3)In single-factor experiments,the rate of histamine removal,loss of AAN,energy consumption and the loss of volume of fish sauce were examined at various values of input current(3,4,5,6 and 7A)and pH value(3,4,5,6 and 7)and flow velocity(10,20,30,40 and 50 L/h).Through the experiments,the optimal condition of electrodialysis was as follows: the input current of 4-6A,pH value of pH 3-5 and flow velocity of 20-40 L/h.(4)According to the response surface analysis,regression equations which give the rate of histamine removal and loss of AAN of the fish sauce as a function of the initial values of input current,pH value and flow velocity were obtained.It can be concluded from the regression equations that the top three factors affacting the removal rate of histamine were input current > pH value > flow velocity,the top three factors affacting the loss of AAN were input current > flow velocity > pH value.The parameters of response surface were optimized,and the optimum process conditions were as follows: the input current of 5.1A,pH value of 3.77 and flow velocity of 40 L/h.Under the optimum conditions,the rate of histamine removal was 53.4 %,the loss of AAN was 15.5 %.(5)Under the optimum conditions,the desalting rate of the fish sauce after the electrodialysis was half of the original,the color difference was trace;the biggest change in volatile flavor compounds was the decrease of aldehydes content,which led to the diminished in fishy odor;sensory analysis indicated that the acceptable levels of fish sauce after electrodialysis had a sight decrease,but not significant,and the decline in salty flavor just meets people's pursuit of low-salt diet.
Keywords/Search Tags:fish protein hydrolysate, biogenic a mines, electrodialysis, response surface analysis
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