We've just found an amount of silk without any notification of whether it is just silk fibroin or fibroin+sericin combination. Although it looks like cotton wool, we wanna be sure that it doesn't contain sericin.
As far as I am aware of, FTIR allows the detection of sericin in silk. You can refer to this article on the topic: Article Using FTIR spectroscopy to detect sericin on historic silk