2020 Volume 28 Pages 73-80
The effect of protein coating on the cohesion of raw silk made from low-temperature cooked cocoons was assessed. An experimental coating-system was constructed and installed on a reeling machine. The cocoons of Gunma×200, a commercial silkworm race, were cooked using a low-temperature cocoon cooking method and analyzed. Coating was performed in two different places: before and after the kenneru-system. In the case of sericin coating, natural glue proteins of cocoon filaments, the native sericin showed significant improvement in the cohesion of raw silk treated before and after the kenneru-system. On the other hand, the sericin extracted at 121°C did not show any effect on the raw silk cohesion. However, the sericin extracted at 115°C showed a slight improvement in cohesion of raw silk coated after the kenneru-system. The composition of the sericin protein sizes in the prepared sericin solutions was different, and high molecular-weight sericin protein was apparently effective in improving the raw silk cohesion. In addition to sericin, the effect of the gelatin coat on the improvement of raw silk cohesion was assessed. Application of more than 5% gelatin coating before the kenneru-system and 3% gelatin coating after the kenneru-system resulted in significant increase in raw silk cohesion. Furthermore, the gelatin coating did not affect the degumming process. The strength of coated raw silks decreased; however, the strength of the silk fiber itself was not affected.