| The large yellow croaker(Pseudosciaena Crocea),belongs to family Sciaenidae,is one of the most economically important marine fish in Fujian province with high yield.The large yellow croaker roes are the main processing by-products with abundant resources.How to rational utilization of the resources and improve the added value of large yellow croaker products will be the hotspots in the development of large yellow croaker processing.The large yellow croaker roes contain abundant lipids,are expected to be a natural source of high quality fish oil which are rich in omega-3 polyunsaturated fatty acids(PUFAs).However,there are few reports about the extraction,quality control,product development and application of large yellow croaker roe oil.Therefore,this subject first obtained the large yellow croaker roe oil by solvent method,and the effects of storage temperature and time on the quality of fish roe oil were studied.Furtherly,microencapsulation technology was used to produce fish roe oil powder in order to develop new type of large yellow croaker roe oil products.The studies provide new ideas and theoretical support for the high value utilization of large yellow croaker roe.The main research contents and results are as follows:(1)The large yellow croaker roe oil was extracted by different kinds of organic solvents,such as n-Hexane,cyclohexane,isopropanol,ethyl acetate,95%ethanol,and chloroform-methanol.The parameters of phospholipids(PL),peroxide value(POV),free fatty acids(FFA),thiobarbituric acid-reactive substances(TBARS)and fatty acids(FA)composition of large yellow croaker roe oil were investigated.The results indicated that the roe oil obtained with 95%ethanol has the best extraction effect but more severe degree of oxidation,while chloroform-methanol has lower oxidation and better quality.Furthermore,the different proportion of eicosapentaenoic acid(EPA)and docosahexaenoic acid(DHA)to polyunsaturated fatty acids were 89.73%(chloroform-methanol),88.49%(95%ethanol),87.59%(isopropanol),87.21%(n-Hexane),86.25%(cyclohexane)and 82.02%(ethyl acetate).Therefore,chloroform-methanol can be selected as the optimal solvent in extraction of large yellow croaker roe oil.(2)Fish roe oil samples extracted by chloroform-methanol were stored at different temperatures(-20,4,25 and 40℃)for 28 days respectively,and changes in physicochemical indexes(peroxide value,free fatty acid,and thiobarbituric acid-reactive substances)were detected at regular intervals during the storage period.The electronic nose and headspace solid phase microextraction-gas chromatography-mass spectrometry(HS-SPME-GC-MS)were used to analyze the volatile flavor components of samples.The results declared that peroxide value,free fatty acid,and thiobarbituric acid-reactive substances increased significantly during the storage period,and the volatile flavor compounds and relative content changed obviously.The oxidation index of fish roe oil storaged at-20°C and 4°C increased slightly,while 40°C temperature treatment group had the largest increase,and the oxidation degree of fish roe oil storaged at40°C temperature was the most serious.(E)-4-Oxohex-2-enal,3,5-Octadien-2-one,2-Nonanone,1,4-Cyclohexanedione,3,3,6-trimethyl-1,5-Heptadien-4-one,2-(2-Pentenyl)furan and acetic acid were the most significant volatile flavor compounds,which increased with increasing temperature.Consequently,storage at low temperature conditions is beneficial to delay the oxidation of large yellow croaker fish oil.(3)The sodium starch octenyl succinate and maltodextrin were used as the composite wall materials.The response surface methodology(RSM)was applied to optimize the microcapsule process by spray drying of the large yellow croaker roe oil.And then,the physicochemical properties and the quality of microcapsules were measured and evaluated.The results showed that the optimum conditions of microcapsule process were determined as follows:sodium starch octenyl succinate/maltodextrin ratio for 1:1,total solids content for 20%,core-to-wall ratio for 1:1.5 and inlet air temperature for 80℃.Under these conditions,the microencapsulation efficiency was 97.87%.In addition,the microcapsules prepared under the optimal process conditions had good sensory quality,whitish yellow powder,slight-fishy smell,no rancidity peculiar smell,fine and uniform particles and good dispersibility.Microscopy structure by SEM also showed microcapsules were nearly spherical in shape with depression surface and the particle size was between 3μm and 20μm.The powders had relatively low moisture contents(1.1%),the bulk density 0.718 g/cm~3,the angle of repose 32.47°and good fluidity. |
