Naturally colored silks are not durable and apt to fade during fabric processing and home laundering due
to the unstable pigment composition and the accumulation of pigment in the surface sericin layer. In this
study, the pigment of naturally yellow-colored silk was isolated, characterized and quantified. A dominant
pigment composition identified by NMR analysis was all-trans-lutein and other five components
were identified as all-trans-neoxanthin, all-trans-violaxanthin, all-trans-a-carotene, all-trans-b-carotene
and 9-cis-b-carotene, according to their characteristic UVeVis spectra and EI-MS data. All six carotenoids
were accumulated in sericin layer and exhibited a remarkable decrease in total content in the outer layer
(220 mg/g), middle layer (117 mg/g) and inner layer (50 mg/g) of the cocoon shell as determined by
analyzing the reeled fiber from one end to the other.
© 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND