Salting-out Extraction Of Effective Components From Processing Liquid Of Sea Cucumber

More than 90% of sea cucumbers must be boiled to prevent them from autolysis when leaving the sea water, which will definitely produce a great quantity of processing liquid of sea cucumber. This kind of processing liquid contains almost the same chemical composition as fresh sea cucumber, such as polysaccharides, proteins, fats, and saponins. Some of them are even more than the processed sea cucumber, such as oil and saponins. The proteins and polysaccharides in the processing liquid of sea cucumber are mostly soluble, so they can be absorbed by the body more easily than those exist in the sea cucumber. If these active ingredients could be fully developed and utilized, a huge economic benefits would be obtained. Currently, almost all the processing liquid of sea cucumber are treated as waste liquid, leading to environmental pollution and huge economic losses. Therefore, to enhance the added-value of sea cucumber and reduce environmental pollution, the ingredients such as polysaccharides, proteins, fats and saponins in the processing liquid of sea cucumber are investigated to recovery in this paper as follows:First, the salting-out extraction behavior of processing liquid of sea cucumber is studied in an aqueous two-phase system (ATPS) composed of different hydrophilic organic solvents and inorganic salts. The results showed that ethanol/sodium carbonate, and tert-butanol/ ammonium sulfate system perform better in extracting proteins and polysaccharides of sea cucumber. The extraction conditions were determined and optimized. For ethanol/sodium carbonate system the optimum conditions are:16%(w/w) ethanol/12%(w/w) sodium carbonate/72%(w/w) processing liquid of sea cucumber, temperature 37℃, the yields (Y) for proteins and polysaccharides of 96.9% and 90.6%, respectively. For tert-butanol/ ammonium sulfate system, the process was conducted by adding t-butanol (1:1.5, v/v) and 30%(w/v) ammonium sulphate into the processing liquid of sea cucumber at room temperature, resulting in the highest yields (Y) for proteins and polysaccharides of 99.6% and 92.1%, respectively. These results demonstrated that salting-out extraction is effective for the extraction of proteins and polysaccharides from the processing liquid of sea cucumber. Meanwhile, removal of heavy metal ions from the processing liquid of sea cucumber was studied in salting-out extraction composed of ethanol/sodium carbonate. The results showed that this system can effectively reduce the heavy metal content. Almost all of the arsenic(As),mercury (Hg) and plumbum (Pb) are removed, while the residual ratio of cadmium (Cd) is 13.8%.Secondly, a three-liquid-phase extraction system (TLPS) composed of n-hexane/ ethanol/sodium carbonate/water was investigated to extract oils, saponins, proteins and polysaccharides from the processing liquid of sea cucumber simultaneously. The effects of the ratio of ethanol and sodium carbonate, concentration of n-hexane and temperature were investigated. The results showed that the system composed of 28%(w/w) n-hexane/16% (w/w) ethanol/12%(w/w) sodium carbonate at 37℃can distribute 86.9% f the fats in the top phase,82.9% of saponins in the middle phase,92.9% of proteins and 93.2% of polysaccharides in the interface between the top and middle phase, while mercury, plumbum, arsenic and cadmium and other heavy metal ions in the bottom phase. When the system was progressively enlarged to 40 mL,3 L,20 L and 30 L, the yields for polysaccharides, proteins and oils decrease only by 1%,2.8% and 1%, respectively, from 20 mL to 30 L, showing unobvious effect of scale up. The recovery of salt and solvent in TLPS was also studied, and the results showed that the recovery of n-hexane, ethanol, and salt is 90%,80%, and 72%, respectively. Recycling materials for the extraction, the yield for proteins and oils decreases by 1.96% and 5.4% respectively comparing with the pure system, which could meet the separation requirements. In summary, the salting-out extraction system can extract and separate various components from the processing liquid of sea cucumber. This technology is a simple operation at mild condition and low cost. It is easy to enlarge and can reduce the risk of heavy metal poisoning.Finally, based on experimental parameters, we have designed the process and equipments for salting-out extraction of processing liquid of sea cucumber, and estimated the economic of the entire process. The design consists of three parts:the first one is design of storage tanks for raw materials; the second is design of extractor; and the last is design of evaporators, dry instrument, and containers for products from different phases. The economic analysis showed that raw material costs and sales expenses are the most important factors in this process, accounting for 77.8% of the total cost. The sensitivity analysis showed that the cost of sales expenses is the key factor influencing the profit, followed by the cost of hexane and ethanol.