Preparation and physical and chemical properties of silk fibroin peptide

Chinese. 为了研究丝素肽的制备工艺及其理化性质，用沸腾的质量分数40% CaCl2溶液溶解精炼的废蚕丝，将制得的丝素蛋白盐溶液加入Alcalase酶进行酶解反应，酶解液经超滤器超滤后的丝素肽溶液再用纳滤设备脱盐，得到的溶液进行喷雾干燥即制得丝素肽粉，同时对丝素肽粉的理化性质进行测定。结果表明，制得的丝素肽粉中丝素肽含量为929.6 g/kg；当其水解度为17%时，丝素蛋白水解产物中主要组分的相对分子质量分别为249和762，含量分别约占72.9%和15.5%，当水解度为21%时，丝素蛋白水解产物中主要组分的相对分子质量分别为209和668，含量分别约占84.4%和7.2%；丝素肽主要氨基酸（甘氨酸、丙氨酸、酪氨酸和丝氨酸）的含量之和占其氨基酸总量的85%左右；其平均疏水性为2.29 kJ/残基；丝素肽在pH为2～10时具有很好的溶解性；丝素肽溶液的黏度较小，且随浓度增加，丝素肽溶液的黏度增加不大。可见，丝素肽具有良好的理化特性和营养特性，应用前景广阔。

English. To study the preparation technics, and physical and chemical properties of silk fibroin peptide, refined waste silk was dissolved in 40% calcium chloride solution. The solution obtained was hydrolyzed with alcalase, then ultrafiltrated, and after these processes, desalted by nanofiltration (NF). Finally the desalted solution was sprayed dry. The physical and chemical properties of silk fibroin peptide powder were determined. The results showed that the content of silk fibroin peptide in silk fibroin peptide powder was 929.6 g/kg. The relative molecular weights of the main components of silk fibroin hydrolysate with DH 17% were 249 and 762, respectively, and the water contents took up about 72.9% and 15.5%, respectively. The relative molecular weights of the main components of silk fibroin hydrolysate with DH 21% were 209 and 668, respectively, the contents taking up about 84.4% and 7.2%, respectively. The main amino acids of silk fibroin peptide were glycine, alanine, serine and tyrosine, taking up 85% of a total amount of amino acid. The average hydrophobicity was 2.29 kJ/residues. The solubility of silk fibroin peptide was very good in the pH ranging from 2 to 10. The viscosity of silk fibroin peptide solution was low, and increased lentamente with the concentration increased. So silk fibroin peptide had good physical, chemical and nutrient properties, and would have a wide application foreground.