| Silk is a kind of polymer silk fibroin fiber produced by Bombyx mori. Its outer layer is coated with sericin protein, which mainly used for the raw materials of silk reeling industry and silk flossing industry. In silk reeling industry and silk flossing industry, two by-products(sericin and silkworm pupae) are not allowed to ignore. In machining process, the silkworm pupae is only tried to use as low additional value livestock feed additives, and many of the silk sericin is discarded directly with a large number of silk reeling liquid and silk flossing alkaline waste liquid, which not only causes serious environmental pollution, also causes waste of protein resources. So, the recycling of silk sericin and high value-added utilization of silkworm pupae has always been the focus of this research field.Surfactant is of great demand in daily life, various types of surfactants in recent years are listed in the market, it is also one of the main research hotspot both in and out of the country, and the amino acid type anionic surfactant is one of the most popular. In this paper, combining with the demand of silk processing industry and the problems, we use silk fibroin, silk sericin and silkworm pupae protein as raw material to obtain silk fibroin amino acids, silk sericin amino acids and silkworm pupae amino acids by recycling or separation, purification and degradation methods, and, synthesized three laurel acyl silk protein amino acid sodium of surfactant through the classic methods of Schotten-Baumann shrinkage, respectively. The three kinds of anionic surfactant are referred to as lauryl silk fibroin amino acid type surfactant(SFA), lauryl silk sericin amino acid type surfactant(SSA) and lauryl silkworm pupae amino acid type surfactant(SPA), and has carried on the analysis and test of surface features. In order to apply them for daily cleaning products, we mixed three kinds of amino acid type surfactant with mice feed in proportion and carried out eight weeks of biological safety evaluation test in mice to analyze the growth, development and metabolism of mice.The main work of this paper is as follows:(1) In this paper, self-made machine was used to simulate industrial silk flossing production processing. We use 50 kg silkworm cocoon doupion as raw material, after processing, 18 kg(drying) silk sheet(silk fibroin protein fiber), about 100 L alkali sericin waste water, 20 kg pupa(drying) and some waste silk formed by husks and tetelettes were prepared. ? Boiling the collected waste with 0.2 % sodium carbonate solution for 30 min, repeated once, remove the degummed silk fiber, cleaned and dried. Then silk fibroin fiber will be collected and put it into 121 degrees C(0.235 MPa) hydrolysis for 30 min, the pale yellow silk protein hydrolysate was received, followed by adjusting its p H to 4.0, after filtration and purification, get the powder by spray drying and set aside. ? Sericin waste firstly put through PP(polypropylene) fiber and activated carbon for coarse filtration, and then use the ultrafiltration membrane for ultrafiltration separation, received a total of 10 L containing high molecular weight sericin polypeptide and 5 L of small molecular weight. After that, they were spray dried. Finally, we get the high purity of the high molecular weight of silk sericin powder and small molecule sericin protein powder respectively. ? 20 kg dried silkworm pupa was successively pressed and defatted by oil expeller and n-hexane, about 4 L silkworm pupa fatty acid and 16 kg of defatted silkworm pupa powder(silkworm pupa protein) were obtained. Then the defatted silkworm pupa powder was put into 125 degrees C(0.235 MPa) to hydrolyze for 30 min, a lot of pupa protein hydrolysate was received. After that, the pupa protein hydrolysate was put into PP fiber and activated carbon filter, followed by deacidification. Finally, the orange red pupa protein hydrolysate was obtained. The powder after spray dried is used as the raw material for the synthesis of the surfactant.(2) The silk fibroin amino acids, silk sericin amino acids and pupa amino acid are configured for 20 % of the amino acid solution, p H value adjusted to 8.0-9.0. Three kinds of amino acid solution were placed in the reaction kettle with a programed control thermometer and stirring device, adding an appropriate amount of acetone and reaction temperature control in less than 5 degrees C, followed by a slow dropping lauroyl chloride, also drops 2.0 mol/L Na OH solution, enable reaction system p H value control in about 9.0-10.0. After finishing dropping, makes the temperature of the reaction to 20 degrees C for 4 h. After the reaction, adjust the reaction mixture of the p H value to 1.0-2.0, the milky white and red brown precipitate, namely for crude products. Finally, will receive precipitation followed by the use of the hot water and petroleum ether washing a few times. Then the product was dissolved in anhydrous ethanol in 55 degrees C under the dripping Na OH ethanol solution enable reaction solution adjusted to p H 7.0-8.0, continue to react at room temperature for 30 minutes. The organic solvents used in the whole reaction are concentrated and recovered by the rotary evaporation apparatus. The synthesized surfactants were then analyzed by IR spectrum to characterize their structure. The production rate of synthesis of the three kinds of laurel acyl amino acid surfactant sodium is about 78 %, 75 % and 70 % respectively. Considering the CMC, γCMC, foaming capacity and the emulsifying power, the SFA displayed a good property of surface among three kinds of surfactants.(3) To study the effect of surfactant on growth, development and metabolism of mice, we mixed the surfactants which were synthetized above with mice normal diet, and the new diets were fed to the mice for 8 weeks with different proportion. Experimental results show that eating different proportions of the diets mice presents the phenomenon of weight gain compared to the normal group; the experimental mice liver coefficient, kidney coefficient had no significant difference compared to the normal group, the spleen coefficient of 2.5 % SPA group increased significantly compared to the other groups, suspected to be caused by individual differences; in experimental animals, the quality of abdominal fat pads of mice were significantly increase compared to the normal group. The blood index of mice in each experimental group compared with the normal group showed no significant difference. In each experimental group, the detection of oxidase of liver tissue from mice, GSH-PX, MDA, T-AOC, T-SOD activity showed no significant difference compared to normal group. Pathological sections of mice in each experimental group of liver, kidney, spleen presents no significant difference compared with normal group, which can infer surfactant added to the diet will not affect digestion and absorption of mice. Through the detection of key enzymes of lipid metabolism of mice m RNA expression, the quantitative PCR results showed that surfactant will not stimulate the expression of key enzyme genes of lipid metabolism in mice.To sum up, in this paper, by using the waste sericin, waste liquid and silkworm pupae of silk flossing processing as raw materials, we synthesized three kinds of amino acid sodium salt of anionic surfactant. After oral test in mice, the mice liver, kidney, pathological tissue and blood index and antioxidant enzymes have no obvious adverse effects. This fully confirmed that three kinds of amino acid surfactant have no adverse effects to the growth and development of mice. It also fully shows that the three kinds of amino acid surfactant are of biological safety. They can be used in people’s daily supplies as cleaning products. |
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