Analysis of “Cévennes White” cocoon color

Abstract

The National Agriculture and Food Research Organization (NARO) in Japan maintains 27 native European strains of the domesticated silkworms (Bombyx mori). Many of them are distinguished by their flesh color, oval cocoon shape, high yarn volume, and thick cocoon filament. Among the native European varieties, “Cévennes White” is a white cocoon that is not commonly found. This cocoon has relatively thick filaments that are shallowly wrung-out and bale-shaped. Court costumes from the French Rococo era were restored using “Cévennes White.” Several features of the court costume, such as whiteness, lightness, three-dimensional shape, and softness, are attributed to “Cévennes White.” Therefore, to examine the whiteness of “Cévennes White,” we first measured cocoon color with a colorimeter. The results showed that “Cévennes White” had a lower yellowness index as well as less whiteness than the Chinese or Japanese white cocoon strains. In addition, the silk proteins of “Cévennes White” exhibited a strong blue fluorescence, as revealed by a three-dimensional fluorescence analysis performed using a fluorescence spectrophotometer.