Study On Effect Of Macroporous Resin Adsorption Treatment Of Tilapia Scraps Enzymatic Hydrolysates

Although the enzymatic hydrolysates of tilapia scraps are rich in bioactive peptides,amino acids and minerals,its turbid apperence,heavy bitterness and fishy smell and severe sensory quality are a serious constraint to the development and utilization in the food industry.In this study,the enzymatic hydrolysates of tilapia scraps were used as raw material.and were treated with macroporous resin in the way of static and dynamic adsorption,then adsorption characteristics were researched,simultaneously the optimization of adsorption and elution were studied.Its application and development in food field was promoted and a simple,economic and efficient method to remove bad flavor of aquatic proteolytic digestion liquid was provided with macroporous resin treating enzymolysis hydrolysates.The main results were as follows:1.Protein preservation rate and sensory score for the index,two adsorption resins were preliminary screened from seven kinds of macroporous adsorption resin through static adsorption method,which are known as AB-8 and DA201-C.The kinetic equations were examined and the results showed that the adsorptions of protein on AB-8 and DA201-C were fitted to pseudo first-order kinetic model with R2 of 0.996 and 0.925,respectively.The Freundlich equation was the best fit by AB-8(R2 = 0.93)and DA201-C(R2 = 0.95).In this study,the effect of adsorption time,resin amount and p H on the adsorption of the resin for two absorption resin was studied.The result showed that the remaining protein of enzymatic hydrolyzates treated with AB-8 was 85.92% and its sensory score was 2.0 under the optimal condition that mixture was added 5.0% resin with p H value adjusted to 6.0 and absorbed for 1.5 h while the remaining protein of enzymatic hydrolyzates treated with DA201-C was 74.52% and its sensory score was 1.6 under the optimal condition that mixture was added 4.0% resin with p H value adjusted to 5.0 and absorbed for 2.5 h.2.The adsorption breakthrough curve of enzymatic hydrolysates protein was studied,and the dynamic adsorption capacity of AB-8 and DA201-C resin was 6 BV and 10 BV,respectively.The influence of sample concentration and flow rate on absorption and the optimum conditions of the dynamic elution were studied.The results are as follows: for AB-8 sample concentration of protein was 7.2mg/m L and flow rate was 5BV/h;sample concentration of protein was 7.2mg/m L,flow rate was 3BV/h.The influence of eluent composition and elution rate on macroporous resin elution and the optimum conditions of the elution were studied.The results are as follows: for AB-8 eluent was 40% ethanol,elution rate is 3BV / h;for DA201-C eluent was 60% ethanol,elution rate was 3BV / h.3.The enzymatic hydrolyzate treated by absorption was analyzed by the sensory evaluation,basic composition and some unconventional indicators.After absorption treatment,the yellow color degraded,and the fishiness and bitterness also became light.Protein loss rate were 2.02% and 9.05%,and an increased relative content of fat and ash.The enzymatic hydrolyzates before and after absorption treatment,as well as the molecular weight distribution of adsorbed components,were analyzed by the high-performance size exclusion chromatography(HPSEC).The results show that the resin prefers to absorb the components with molecular weight less than 1k Da.and decreased by 49.1% and 53.6%.The components with molecular weight less than 1k Da in ethanol eluent account for above 68%.The results of amino acid showed: the relative content of bitter amino in both of the hydrolysis and free amino acids decreased.Generally,the adsorption ability of DA201-C is better than AB-8;the resin has a selective adsorption on the amino acids;also,the resin would absorb both the free amino acids and some kind of polypeptide.The volatile flavor compounds in the enzymatic hydrolyzates before and after the treatment of resins were analyzed by the HS-SPME-GC-MS.Among the volatile flavor compounds in the enzymatic hydrolyzates treated with absorption,the content ratio of aldehydes,esters and nitrogen-containing substances got deceased,the aldehydes substances down from 35.94% to 31.22% and 34.01%,and the esters substances down from 4.03% to 2.38% and 1.99%.and Nitrogenous down from 13.95% to 13.60% and 12.07%;The relative content of acids and hydrocarbon were increased,the former up from 12.47% to 23.03% and 17.39% and the latter up from 9.34% to 10.18% and 14.11% respectively.