Development And Quality Research Of Prepared Keta

Keta is a special aquatic product in Heilongjiang Province,but its deep processing level is quite low.Developing keta on prepared food can enrich the kinds of fish prepared food and fill the blank of prepared keta.In this paper,the pickling technology,frying technology and microwave reheating technology of keta were determined,the quality and flavor change of fish during freezing storage were studied.The specific research contents and results are as follows:The effect of different seasoning content on the quality and flavor of prepared keta was studied.Through the determination of water content,tenderness and sensory quality,the pickling technology suitable for industrial production was selected.The results showed that the optimal pickling technology of prepared keta was salt content 1.2%,white vinegar content 2.0%,cooking wine content 1.2%,raw soy sauce 1.8% and 0.20% of black pepper,under this content,the fish meat has high water content and moderate shear force,and the overall acceptability score of sensory evaluation is the highest.The effects of different frying temperature and frying time,on the quality and flavor of the prepared keta were studied,and also the microwave reheating power and reheating time.By measuring the moisture content,yield,tenderness and sensory quality,the reheating technology suitable for industrial production of the prepared keta was selected.The results showed that the optimal frying temperature was 160?,the frying time was 100 s,the optimal reheating power was 720 W,and the microwave reheating time was 120 s.Raw meat and prepared keta were determined by electronic nose,and qualitative and quantitative analysis was carried out by solid-phase microextraction gas chromatography-mass spectrometry.The results showed that aldehydes,ketones,alcohols,acids,alkanes and aromatic compounds were the main volatile compounds.The main effect of frying on flavor was the decrease of aldehydes with fishy smell.During the storage period,with the lipid oxidation and microbial reproduction,the main flavor substances gradually changed,among which,the main flavor substances affected by frozen storage of 1-2 month were octanal,?-pinene,?-laurene,dlimonene,etc.;the main flavor substances affected by frozen storage of 3 month were 1,6-octadiene-3-ol,(E,E)-2,4-decadienal,cycloheptadiene;the main flavor substances affected by frozen storage of 4 month were ethanol,heptanal,2,4-octadienal,acetic acid,3-heptanone,etc.Through the determination of the TAMC,POV,TBARS,chroma,shear force and sensory evaluation of prepared keta in 0,1,2,3,4 months of storage,it was found that with the extension of storage time,the physical and chemical indexes and sensory indexes of fish meat had a relatively significant change trend,including discoloration,softening,microbial breeding and fat oxidation,which led to the overall acceptable sensory evaluation was significantly reduced.The a* value of prepared keta in the control group was 14.12 in the first month of storage,and decreased to 5.51 in the fourth month of storage,which resulted in significant discoloration(P < 0.05).The shear strength of the control group was 85.63 N in the first month of storage,and decreased to 63.56 N in the fourth month of storage,which resulted in significant softening(P < 0.05).When the adding amount was 0.06%,the TAMC was 4.62 lg CFU/g in 3 months,which was significantly lower than that of the control group(5.17 lg CFU/g).The TBARS was 1.98 mg MDA/Kg,which was also significantly lower than that of the control group(2.37 mg MDA/Kg).The results showed that the addition of mint extract had a good inhibitory effect on the TAMC and the formation of oxidation.