| Mussel cooking juice is a kind of water, which is produced in theprocess of mussel freezing or canning. When 1 ton mussel products aremanufactured, it will produce 1.5 tons this water at the same time.Usually, we just dump this juice, which contains a large amount ofprotein, total-sugar, into the ocean. This can cause the rich nutritionalpollution. Therefore, the juice should not be released without any efficienttreatment in order to prevent a negative impact on the environment. Onthe other hand, concentrated cooking juice could be used as flavoring inhuman food.Mussel is a sort of coastwise dermarsal double-hull seashell, whichhas a series of characters, such as wide distribution, low activities and soon. On the other hand, it has the ability to enrich the pollution and heavymetals. Finally, it can affect the content of heavy metals in the musselcooking juice. Therefore, it is important to reduce the content of heavy metals in the juice.Nowadays, only a few methods have been applied to decrease thecontent of heavy metals in food. For example, ethylenediaminetetraaceticacid can combine heavy metal ions to form compounds, which arewater-soluble, so this method can not be applied to mussel cooking juicewhich is a water solution. In this experiment, phytic acid and chitosanwere applied to reduce the content of heavy metals in food. The RSREGprocedure of SAS software was used for the response surfacemethodology analysis. Data was analyzed to fit the followingsecond-order polynomial equation to all dependentvariables: Y=β0+sum from i=1 to nβiXi+sum from i=1 to nβiiXi2+∑sum from i＜j=1 to nβijXiXj. Three dimensionalresponse graphs and contour plots of predicted values of the model ofRSM were plotted using OriginPro. 7.5.Phytic acid has both phosphate radical and hydroxyl groups whichhave a high capacity to form insoluble complexes (phytates) with heavymetal ions. The effects of pH, heating time, heating temperature and thequantity of phytic acid on cadmium decreased ratio, chromium decreasedratio, protein residual content and total-sugar residual content wereinvestigated by single factor experiments. It educed the ranges inquadrature reaction. By the quadratic orthogonal rotation combinationdesign, it educed the four values of cadmium decreased ratio, chromiumdecreased ratio, protein residual content and total-sugar residual content. Response Surface Methodology analysis showed that the optimizeconditions were pH=8.5, time=21.9hours, temperature=88℃andchitosan=0.90%.Chitosan is a biopolymer made up of glucosamine units. It has bothamine and hydroxyl groups. So it could chelate with heavy metal ions bythe cage molecule that formed by hydrogen bond and/or electrovalentbond. The effects of pH, heating time, heating temperature, the quantityof chitosan and rotate speed on cadmium decreased ratio, chromiumdecreased ratio, protein residual content and total-sugar residual contentwere investigated by single factor experiments. It educed the ranges inquadrature reaction. By the quadratic orthogonal rotation combinationdesign, it educed the fours values of cadmium decreased ratio, chromiumdecreased ratio, protein residual content and total-sugar residual content.Response Surface Methodology analysis showed that the optimizeconditions were pH=7.5, time=7.3hours, temperature=73℃, chitosan=227mg/35mL, rotate speed=271r/min.Compared with the phytic acid method, the chitosan method couldgive better application prospect. The infrared spectras were proved thatthe complexation reaction could happen between chitosan with chromiumion and cadmium ion.
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