Evaluation of Silk Fibres Obtained by Degumming Tasar Cocoons Using Antheraea mylitta Cocoonase and the Existing Classical Methods: A Comparative Study

Abstract

Antheraea mylitta cocoonase a proteolytic enzyme is reported to have its potential application in cocoon degumming. Although, no detailed study on the properties of silk fibre obtained using this naturally secreted protease is available. Therefore, an attempt has been made to evaluate the tasar silk fibres obtained using A. mylitta cocoonase and compared to that obtained from trypsin and papain along with the existing chemical based degumming methods. The silk fibres obtained were characterized using various parameters, such as FT-IR, DSC, TGA, colorimetry, tensile strength, XRD, Yellowness Index, CHNS and FE-SEM. The FE-SEM images depicted that the surface of the CDSF (Cocoonase degummed silk fibre), PDSF (Papain degummed silk fibre) and TDSF (Trypsin degummed silk fibre) was comparatively smooth to that of the HDSF (H₂O₂ + Neutral soap degummed silk fibre) and SDSF (Na₂CO₃ + NaHCO₃ degummed silk fibre). The absorption pattern in FT-IR indicated slight shifting or vibration of the functional group in SDSF silk fibre. Moreover, much variation was not observed in the mechanical properties of silk fibres. Minor variation in 2θ position can be observed from the XRD plot in case of HDSF and SDSF silk fibres. The DSC graph showed remarkable differences in the thermal properties of SDSF silk fibre comparatively to that of the HDSF and other silk fibres. The TGA study infers that PDSF and CDSF silk fibre were more stable to the degradation. Thus, the present study observes that cocoonase was found to be efficient in degumming tasar cocoons. Therefore, in the future cocoonase can be adopted as one of the methods for degumming. This will aid in a new dimension towards the way of enzymatic silk processing.