Development of new chemistry teaching materials using silkworm cocoons

~ Chemical properties of sericin and fibroin

Abstract

　　We have been using silkworms as biological materials such as the breeding of it, observation / dissection, crossing experiments of crossing tests. Sericin and fibroin of silkworm cocoons are processed into powder and film and are being researched and developed as new materials. However, their chemical properties have not been treated as experimental teaching materials. In this study, we tried developing new chemistry teaching materials focusing on the chemical properties of sericin and fibroin, and conducted a practical chemical experiment and a questionnaire survey.

　　Sericin was fractionated into two by the difference in solubility between hot water and alkaline aqueous solution. According to the scanning electron microscope (SEM) image, we confirmed the presence of sericin in cocoon thread treated with hot water. The fibroin aqueous solution produced from cocoons tends to undergo gelation, so long-term preservation is difficult. Therefore, to make it a practical chemistry experiment sample, we examined long-term storage methods of fibroin aqueous solution at low temperature. We confirmed that the fibroin solution frozen at -80 °C maintained the state of the aqueous solution even after thawing for over 6 months. The results of questionnaires to people who participated in chemical experiments using silkworm cocoons suggested that experiments on the chemical properties of sericin and fibroin could be expected to raise awareness about methods other than clothing fibers.