Degumming of Persian silk with mixed proteolytic enzymes

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 55 degrees C 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. (c) 2007 Wiley Periodicals, Inc.