Effects of Low-Temperature Cocoon Cooking Method and Chemicals on Raw Silk Cohesion and Physical Properties

Abstract

　　Differences in raw silk cohesion and physical properties between usual and low temperature cocoon cooking methods were assessed. Cocoons of a commercial silkworm race, Gunma × 200, were used for these analyses. Physical properties such as stress and strain were slightly but significantly lower in raw silk made from low-temperature cooked cocoons compared to the properties of usually cooked cocoons, although no significant difference was found for Young’s modulus. The raw silk surfaces of usual and low-temperature cooked cocoons after reeling showed no significant difference, and binding of cocoon filaments was observed. However, the cohesion of raw silk made from low-temperature cooked cocoons was significantly lower. To investigate factors affecting the reduction of cohesion, further analyses were performed. Results revealed that both detergent and alkaline agent used in low-temperature cocoon cooking method adversely affected raw silk cohesion. In addition to cohesion, reeling tests were performed to ascertain the influence of detergent and alkaline agent used with cocoons during low-temperature cooking. Reeling tests revealed that alkaline agent treatment lowered the raw silk percentage of cocoon and the neatness, although those properties recovered when treated concomitantly with detergent. Furthermore, results demonstrated that reelability was improved when cocoons were treated with a combination of detergent and an alkaline agent.