| Monopterus albus is a kind of characteristic freshwater fish with high protein content and concentrated distribution and cultivation.It is widely loved by consumers in recent years because of its high nutritional value,good taste and nourishing health.In 2020,307,200 tons of eel were farmed in China,and in recent years,both export and farmed scale have been expanding.According to statistics,the national demand for eel is 3 million tons,and there is a huge gap with the current annual output.A large part of the reason is that the shelf life of eel after death is short,the secondary processing industry is backward,and the sales model is limited to the single model of live sales,with low profits.Therefore,the research on the preservation technology of eels and the development of new eels food has broad prospects and economic benefits.The main contents of this paper are as follows:(1)at first,this paper measured the at 4 ℃ under the conditions of refrigerated storage eel meat volatile base nitrogen,total number of colonies and p H,made clear under the condition of the eel’s shelf life for 4 days,irradiation could extend the shelf life of eels to 25 days at most.and irradiation dose was positively correlated with storage shelf life.However,high dose irradiation could destroy the original flavor of eel meat,and combined with other nutritional indexes,the best irradiation dose of eel was recommended to be 6 k Gy.During the storage period of eel,the changes of adipose-related indexes in irradiation group and non-irradiation group were studied.With the increase of storage time,the fat decomposition of non-irradiated group was slower than that of irradiated group,which indicated that irradiation promoted the decomposition of fat of eels.Moreover,by measuring the content of malondialdehyde and lipid peroxides in different storage periods,it was further verified that irradiation promoted the fat decomposition of eels.The results of volatile flavor substances showed that alkenes and aldehydes in the nonirradiated group increased significantly after the shelf life,but compared with the irradiated group,more volatile flavor substances in the irradiated group were detected during the shelf life of eels,which was related to fat oxidation.(2)Protein-related indexes of 6 k Gy irradiation group and non-irradiation group were studied during storage of eels.The results showed that: Eel meat was relatively rich in amino acids,including many essential amino acids,and with the increase of storage time,control group total amino acids content changed little,and irradiation group showed a trend of increase after the first reduce the total amino acid content,and compared under the same time total amino acid content of the irradiation group and the control group,the irradiation group were higher than the control group.These results indicate that γ rays can also promote the peptide chain forging and splitting of protein to amino acid transformation under 6 k Gy irradiation condition.Low field nuclear magnetic resonance(NMR)analysis results show that with the increase of storage time,eel flesh of flowing water,free water content of bound water,Immobile water are gradually reduced,This means that there is a significant loss of juice from the eel meat during storage,and without relaxation spectrum integral in moving to the left of the irradiation group eel,molecular fluidity is reduced.This indicates that in addition to water loss,water also migrates from free water to bound water during storage.Compared with the irradiation group,the relaxation signal of T21 segment of eels was lower after irradiation,indicating that irradiation destroyed the macromolecules binding with water in eels.Biogenic amine results show that the eel produces in the process of storage and spermine,histamine,cadaverine and putrescine,and increased with time,the irradiation group and the biogenic amine content of the irradiation group increased,under the condition of refrigerated storage,storage eel within ten days of biogenic amine content does not exceed the relevant standards,There was no significant difference in biogenic amine content between irradiated and non-irradiated groups.Irradiation did not promote the formation of biogenic amines.(3)This paper also developed an irradiated refrigerated raw eel fillet product.Through experiments,different packaging materials were screened and the formula of the product’s fresh-keeping liquid was determined.The sensory evaluation results showed that under 6 k Gy irradiation and 4℃ refrigerated storage conditions,Selection of polyamide-high temperature of polypropylene-four layer composite aluminum foil,polyester film(PA/RCPP/aluminum foil/PET)for vacuum packing,by adding food additives: TBHQ(TBHQ),potassium sorbate,vitamin c,sodium pyrophosphate,sodium tripolyphosphate of fresh eel slices in 5 days still keep in good taste. |
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