Effect Of Plant-source Extracts On The Quality Of Pomfret(Pampus Argenteus)during Ice Storage

Pomfret(Pampus Argenteus)of the family Stromateidae is a benthopelagic fish species distributed along the coast of China from the Bohai Sea to the East China Sea and the South China Sea as locally named butterfish,is the most popular fish in China that possesses high economical value,nutritive value and edible value.As a result of the intense market demand and the excessive commercial fishing,the amount of pomfret declined rapidly and the species is now considered overfished.Just like other aquatic products,due to the influence of geography,climate,seasons and other conditions,pomfret is easy to be spoiled in the periods of processing.Bio-preservatives from plants have been widely used in the preservation and processing of aquatic products,which have the advantages of wide source,low cost and good application prospect.Four parts of research on pomfret preservation were carried on in this paper in order to improve the quality of pomfret during ice storage:First,three different concentrations of GBLE(2.5 mg/m L,5 mg/mL,and 10 mg/m L)on the preservation effect of iced pomfret were studied.The change of sensory analysis showed that samples treated by GBLE have a good inhibitory effect on fish quality decline.Through the changes of total viable counts(TVC),GBLE has certain inhibitory effect on microbial in the surface and internal of pomfret,so it can delay the quality decline and enhance economic value.The results showed that 2.5 mg/m L GBLE can keep the better characteristics of most texture parameters in tolerance level,inhibit lipid oxidation,protein degradation and microorganism growth significantly when compared with the controlled.Second,the effects of 2.5 mg/mL GBLE and 2.5 mg/mL BBE on the quality of pomfret(Pampus argenteus)during ice storage were investigated in this part.Different parameters,such as sensory evaluation,TVC,physic-chemical index(K value,TVB-N,TBA,p H value)were used to evaluate the quality of Pampus argenteus with 3 days interval.The results of quality indexes showed that samples with GBLE and BBE treatment could keep the better sensory scores,lipid oxidation,protein degradation and the growth of microorganism in samples with treatment could be inhibited significantly.GBLE could extend the shelf life at least 3 days.It can be seen from the change of K value and TBA value,GBLE and BBE had good inhibition activity on fish enzyme,and using them could significantly slow down the freshness decline,prolong its shelf life and enhance its economic value.In addition,the color of BBE is more evident than that of GBLE and it shows almost no influence on the inherent characteristics,so it can make up for the adverse effects of tea polyphenols and other plant preservatives on the surface of pomfret.Therefore,GBLE has a good application prospect as a biological preservative.Third,the effects of 1% GBLE and 1% BV on the change of pomfret moisture and protein were investigated during ice storage.Samples without extraction were taken as control group.Change of microbial(TVC),chemical(K value,TVB-N,TBA,pH value,water holding capacity and water activity),protein(actomyosin,total thiol content and Ca2+-ATP content)were investigated,combined with LF-NMR.Sensory score of the samples in control group was lower than 4 after day 9,while samples of GBLE group and BV group had better sensory quality at 12 d and 15 d.From the results of water holding capacity(WHC),water activity and low-field nuclear magnetic resonance(LF-NMR),GBLE and BV can effectively improve the water retention properties of pomfret.The results of protein index(actomyosin content,thiol content and Ca2+-ATPase activity)showed that at 4? storage conditions,GBLE and BV can effectively inhibit degeneration of protein,protect fish samples from spoilage.The shelf life of the control group was 9~12 d,while it could be extended to 15~18 d of treated groups.Last,the effects of slurry ice with GBLE and BV on the quality of pomfret during storage were researched.The sensory and physicochemical(elasticity,conductivity value,pH value,K value,TBA,TVB-N)and microorganisms(TVC,Pseudomonas and Shewanella)were analyzed.There was significant correlation among indexes of PH,K value,TVC and Shewanella.TVC of control group exceeded the limit standard at day 12,while it remained good quality in the treated groups.The growth trend of Pseudomonas is similar to TVC,during the late period of storage,the number of Shewanella in control group increased rapidly,while remains at a low level in treated groups,pomfret in GBLE group had a good antibacterial effect on the growth of Shewanella.The results of quality indexes were shown that samples with slurry ice of GBLE and BV could keep the better sensory scores,lipid oxidation,protein degradation and the growth of microorganism could be inhibited significantly,and the shelf-life of pomfret with slurry ice of GBLE and BV can be extended from 9~12 d to 15~16 d and 17~18 d respectively.