Preparation and Application Performance of a Silkworm Cocoon Protein‐Derived Surfactant

ABSTRACT

A silkworm cocoon protein‐derived surfactant (SPS) was prepared by direct alkaline hydrolysis of non‐degummed silkworm cocoons followed by lauroylation. Under the optimized conditions of 3.5 wt% NaOH, 95°C, and 5 h for hydrolysis, followed by acylation at a free amino acid/lauroyl chloride molar feed ratio of 1.1:1, 25°C, and 2 h, the free amino acid yield and subsequent SPS yield were 73.5% and 75.5%, respectively, corresponding to an overall SPS yield of approximately 55.5%. SPS exhibited a Krafft point below 0°C, an apparent isoelectric point of 7.02, a critical micelle concentration (CMC) of 0.7 g L ⁻¹ , and a surface tension of 31.7 mN m ⁻¹ at the CMC. In model liquid laundry detergents, F‐SPS exhibited a higher initial foam volume (63 mL) than F‐sodium cocoyl alaninate (SCA) (38 mL) and F‐sodium cocoyl glycinate (SCG) (34 mL) as well as higher detergency toward JB‐01 carbon‐black soil. However, F‐SCA and F‐SCG showed better foam stability during prolonged standing.