Study on the distribution of flavonols in the yellow green Irodori cocoon

Abstract

This experiment was conducted to investigate the distribution of flavonols in the yellow green Irodori cocoon, a flavonol rich cocoon harvested in Saitama Prefecture. A free flavonol fraction was prepared by extraction from cocoon shells in 80% methanol. The shells that remained after removing the soluble flavonol were boiled in hot water at 115°C for 30 min to separate sericin and fibroin fractions. The flavonol content in the three fractions, i.e., the free flavonol fraction, sericin fraction, and fibroin fraction, were found to be quercetin equivalent by measuring absorbance at 365 nm. The results were 2227, 132 and 226 µg/g cocoon shell, respectively. It was found that the Irodori cocoon remained yellow after the removal of free flavonol, suggesting that some flavonol resistant solubilization may closely be associated with silk protein. (E-mail: [e-mail])