Silk protein sericin preparation and its characterization

Abstract

The objective of this study was to optimize the appropriate method for the preparation of sericin powder in order to obtain the highest yield and a suitable particle size for cosmetic applications. We investigated the methods for sericin extraction from silkworm cocoon (UB1xUB5 strain) by alkaline and hot water degumming. The highest yield of sericin powder was 21.67 % w/w by hot water degumming, at 100 ํC for 9 hrs with the molecular weight range observed being between 37 kDa to 250 kDa by SDS-PAGE. For alkaline degumming and hydrolyzed sericin by 1.0 N NaOH, we observed the molecular weight to be less than 37 kDa. In the drying process, spray drying yielded less than lyophilization but provided more homogeneous and smaller sericin powder than lyophilization. All sericin powder from the different extraction methods showed similar physical properties on UV and IR spectra due to the same functional groups on their amino acids. However, the morphology of sericin powder obtained from different extraction methods and different drying processes showed different shapes by SEM.