Degumming of Eri silk by Sapindus (soapnut) extract and optimisation by response surface methodology

The present investigation aims to develop a method for degumming Eri silk using Sapindus (soapnut) extract and optimise it using response surface methodology (RSM). The initial experiment was conducted with 10 g/L Sapindus extract for 60 min at a boil, and the initial experiments indicated effective degumming. Further degumming experiments were conducted using RSM to optimise the process parameters, with weight loss being the primary response. The results revealed an optimised recipe for degumming was 9 g/L Sapindus extract at 92°C for 30 min, and the desirability value for this optimised recipe is 0.376. Eri silk that has been alkali-degummed loses more weight than silk degummed with Sapindus extract and soap. Comparatively speaking, degumming with Sapindus extract has a lesser impact on tensile strength than degumming with alkaline and soap. The whiteness, yellowness, brightness, and absorbency values between Sapindus extract and conventional degumming do not significantly differ. Compared with soap and Sapindus extract degumming, alkaline degummed fabric exhibits higher dye uptake. After being degummed with soap and Sapindus extract instead of alkaline, the fabric felt softer. Overall, the results show that both degumming with Sapindus extract and traditional methods are equally effective.