Studies On Recovering Engraulis Japonicus Cooking Soup By Membrane Concentrating Technologies

With the improvement of the technology in on-board processing,it had formed a"fishing-processing integration" of mobile processing mode to produce dried Engraulis Japonicus products.As the annual output had reached 3000 tons per ship,there would be 6000 tons cooking soup every year.The cooking soup contain plenty of protein,amino acid,nucleotides and some other mineral elements,but almost no recovery of this part of the biological resources,and directly discard in environment to cause pollution and waste.In order to achieve clean production methods,so it's a necessary trend for modern aquaculture enterprises recycling the cooking soup.In this study,flocculation and membrane concentrating technologies were used for recovering protein and amino acids from Engraulis Japonicus cooking soup and to explore the concentration technologies,the main contents and results of this paper as following:(1)The concentration effect of the process of combining microfiltration(MF)and nanofiltration(NF)is better than the process of combining microfiltration,Ultrafiltration(UF)and nanofiltration.So,MF-NF process was more simple and available than MF-UF-NF process and suitable for concentrating the cooking soup on board.In the process of MF-NF,the recovery rate of the protein and amino acids were 70.74%and 39.83%?46.64%,respectively.The content of protein increased 3.30 times in the retentate by microfiltration process,but the fishy odor was enhanced.Meantime,the content of amino acid increased 2.71 times in the retentate by nanofiltration process,especially glutamate and aspartate were increased 336%and 672%.Moreover,the fishy odor was disappeared,the flavor of the cooking soup has been effectively improved.(2)Compared with the traditional evaporation,membrane concentration combined MF and NF has the advantage of short time,low energy consumption,high efficiency,avoid thermal chemical reactions and prevent the destruction of the effective content in the thermal sensitive material.So it can better maintain the flavor and color of cooking soup.(3)Before beginning the process of membrane concentration,the flocculation was used as a pretreatment method to reduce membrane fouling and improve concentrating efficiency.Chitosan is a safe and healthy flocculant for food.It was mainly depended on charge neutralization and bridging effects to remove high molecular weight proteins,which was more than 19 kDa,under acid condition.Under alkaline conditions the adsorption was dominant in the flocculating process.Flocculation of water-souble protein in cooking soup using chitosan showed that the optimal efficiency and simple handling was obtained under the condition of chitosan dosage 1 g/L,room temperature,low stirring 10 min and pH 5.5.It was found that 30%of water-souble protein could be removed was and the heavy metals content of Cr,Se,As and Hg had significantly changes,respectively decreased 52.82%,40.59%,21.92%and 13.63%,but a variety of amino acids had not been significantly changes.While the average flux of microfiltration was increased by 9.75%.(4)Under the exploration of optimized parameters of microfiltration,the results showed that inorganic ceramic microfiltration membrane contributed to high flux and short concentrated time,as compared with organic hollow fiber membrane.Ceramic membrane was a promising technology for concentrating cooking Soup.There is no difference of the protein concentration efficiency between 0.14 ?m and 0.45 ?m ceramic membrane,however the integral concentration efficiency was much higher when using 0.14 ?m.The permeate flux increased with temperature,pressure,intermittent feeding and decreased concentration.However,for reducing the concentration of cooking soup,the increased rate of permeate flux was much less than the decreased rate of concentration of cooking soup,then the concentrated protein efficiency was decreased.With the volume concentration increasing,the growth rate of total bacterial count and total volatile base nitrogen(TVB-N)value was minimum at 45 ? compared to 25 ? and 35 ?,and the growth rate of thiobarbituric acid reactive substances(TBARS)value was consistent among them,which demonstrated that the concentrated cooking soup at 45 ? was of good quality.Consequently,the optimal concentrate process was obtained under the condition of 0.14?m ceramic membrane,3 bar,45 ? and intermittent feeding.(5)When nanofiltration with the molecular weight cutoffs of 360 Da was used for concentrating microfiltration permeate,the retention rate of protein and amino nitrogen were small under the operating conditions of 20 bar and 45 ?.Whereas the permeate flux was large,it would reduce the concentration time and maintain the quality of the cooking soup.(6)For the membrane fouling that was produced by concentrating cooking soup,the cleanser with NaOH and SDS was better.The most effective cleaning method was 40 min at 45 ? with solution containing NaOH(1%,w/w)and SDS(0.05%,w/w)and the microfiltration flux recovery ratio was 98.99%,which was 22.85%higher than that of solution only with NaOH(1%,w/w).For cleaning nanofiltration membrane,Chemical cleaning agents containing NaOH(pH 10)and SDS(0.1%.w/w)were used was more effective.The nanofiltration flux recovery ratio was over 96%under the condition of 30 ? and washing 40 min.