Degumming of Persian silk with mixed proteolytic enzymes

Abstract

The feasibility of degumming Persian silk with alcalase, savinase, and mixtures of these enzymes with different alcalase/savinase weight ratios (0/1, 0.25/ 0.75, 0.5/0.5, 0.75/0.25, and 1/0 g/L) was investigated. The results were compared with those of soap degumming, which is a common silk degumming process. The effectiveness of parameters such as the treatment time, concentration of enzymes, and liquid ratio on degumming was studied. The enzymatic degumming process was performed at 558C with an operation time of approximately 30 min, whereas the soap degumming process was carried out around the boiling point in 120 min. The evaluation of the data was carried out through the measurement of the weight loss, strength, and elongation of the samples. The optimum amount of sericin removed was 21.52 wt % for alcalase in 30 min, 20.08 wt % for savinase in 60 min, and 22.58 wt % for soap in 120 min. Also, the enzymatic treatment improved properties of the silk yarn such as the strength (33.76 cN/tex for alcalase and 32.03 cN/tex for savinase) and elongation (20.08% for alcalase and 18.42% for savinase). The obtained values were better than the strength (29.90 cN/tex) and elongation (18.59%) from the soap degumming method. Through the use of an enzyme mixture (0.5/0.5 g/L), good weight loss (22.43%), strength (33.22 cN/tex), and elongation (17.74%) were achieved in 30 min. Scanning electron micrographs confirmed and supported the observed data.

Functional expression of a <italic>Bombyx mori</italic> cocoonase: potential application for silk degumming

“…Alcalase, a commercially available protease prepared from Bacillus licheniformis having the serine protease subtilisin as the major enzyme component, has been explored for use in silk degumming [6][7][8][9]. However, the use of alcalase for silk degumming is difficult to control due to its ability to hydrolyze fibroin to some extent, leading to damage in fibroin [10].…”

Sustainable Textile Wet Processing: Applications of Enzymes

“…Alkaline proteases seem to be the best for removing sericin and improving silk surface properties including handle, shine, and smoothness [4], although they are not in commercial use.…”

Microbial keratinases: characteristics, biotechnological applications and potential.

“…During the degumming process, sericin is hydroblised and solubilised in degumming agents and media (Chopra and Gulrajani 1994). A number of proteases have examined for their ability to degum silk (Arami et al 2007), but some appeared to be only suitable for treating Murshidabad silk (Chopra and Gulrajani 1994.) and many appeared to be low in specificity towards sericin (Freddi et al 2003).…”