Method of Removal of Protein from Silk

Introduction

Raw silk thread obtained from cocoon contains 20% to 30% serecin protein, which affects the luster and strength of the thread and the resultant fabric. Presently used methods of removal of such protein involving extraction of silk with water followed by boiling off in soap with alkali, acid and enzymes has number of disadvantages like higher consumption of energy, use of expensive Marseilles soap, longer reaction time, single usage of soap solution, quality of water affecting the luster of fabric, residual soap causing uneven dyeing & embrittlement, non-removal of protein completely, destruction of protein fiber by alkalies, etc. These disadvantages lead to highly uneconomical process as well as affecting the quality of the end product. Taking these into consideration, a new method has been developed for removal of protein from raw silk, in particular the Mulberry type of silk yarn.

A weighted quantity of silk yarn is reacted with a protease enzyme, which in turn is drawn from fungus, for certain period of time. Quantity of enzyme is related to the weight of the silk fabric used while its activity has to be as per international standards. The reaction of silk fabric and of protease enzyme is carriedout in sodium carbonate-bicarbonate buffer having the desired concentration. Further, the material to liquor ratio is maintained at a specified ratio. A surfactant, preferably a non ionic lissapol-N is added according to the weight of the fabric. On completion of reaction the silk fabric/yarn is washed in water to yield the desired silk yarn, which is devoid of any protein, particularly serecin. The removal of serecin is indicated by loss in weight and retention of luster and softness. Figure 1 shows the scanning electron microscopic scan before processing as per the newly developed method. Figure 2 shows the scanning electron microscopic scan after processing as per the newly developed method

Special Features:

Cost effective process, No expensive material used, Increase in the strength of fiber/yarn, Retention of beter luster by the fabric, No problems of uneven dyeing, embrittlement, etc, Higher efficiency in removal of serecin protein, Possibility for recycling of recovered enzyme.

Prospective Users:

All Silk yarn/fabric manufacturers

Keywords:

Silk, Yarn, Enzyme, fabric

Type of Technology:

Method/Process

Status of IPR Protection:

Indian Patent Application No. 2493/DEL/1998 dated 25.8.1998 with title 'Degumming pf Silk with Fungal Protease' jointly held by IIT, Delhi and Dept. of Bio-Technology, Govt. of India

Contact for more information

The Director
Foundation for Innovation and Technology Transfer
Indian Institute of Technology Delhi
Hauz Khas, New Delhi-110016
Tel : 91-011-26597167, 26857762, 26581013
Fax : 91-011-26851169
E-mail : mdfitt@gmail.com