Finely powdered fibroin and process for producing same

Abstract

Finely powdered high-purity fibroin and a process for producing the same are disclosed. The fibroin is a fine powder of fibroin in nonfibrous and particulate form which has an average molecular weight of not less than 50,000, particle diameters of from 1 to 100.mu., and a bulk density of from 0.1 to 0.7 g/cm.sup.3 as measured in the dry state and which contains at least 50% by weight of hot-water-insoluble fibroin having the .beta.-configuration. The process comprises dissolving a degummed silk material in an aqueous salt solution containing from 5 to 80% by weight of an alkali metal salt or alkaline earth metal salt; dialyzing the resulting aqueous fibroin solution; adding from 1 to 150 parts by weight of an alcohol to 100 parts by weight of the dialyzed aqueous fibroin solution having a fibroin concentration of from 3 to 20% by weight to form a gel of fibroin; dehydrating and drying the gel so formed; and then pulverizing the resulting powder. The fine powder of fibroin thus obtained is useful as an additive for cosmetic and pharmaceutical preparations.

Dependencies are inferred from the claim text.