One-Step Preparation of Silk Fibroin and Sericin from Silkworm Cocoons Using High-Temperature High-Pressure Treatment

Conventional silk degumming processes are primarily designed to recover either silk fibroin (SF) or sericin, resulting in inefficient utilization of silk resources and substantial sericin waste. In this study, a one-step high-temperature high-pressure (HTHP) process was developed for the simultaneous preparation of SF and sericin from silkworm cocoons. To determine the optimum processing conditions, HTHP treatment was performed at 120 °C for 10, 20, and 30 min. The effects of treatment time on the degumming efficiency and the physicochemical properties of SF and sericin were systematically investigated through the characterization of SF as degummed fibers, regenerated solutions, and electrospun fibers, and sericin as solutions and gels. Complete degumming was achieved after 10 min of HTHP treatment, corresponding to a degumming ratio of 25.4%, with no further increase at longer treatment times. While complete degumming was maintained beyond 10 min, prolonged treatment progressively deteriorated the physicochemical properties of sericin and eventually reduced the molecular integrity of SF, as consistently demonstrated across the different material forms. Compared with the conventional soap/soda method, the HTHP process better preserved the molecular integrity of SF while simultaneously recovering an aqueous sericin fraction without chemical degumming. Based on the degumming efficiency and the physicochemical properties of both silk proteins, 10 min was identified as the optimum HTHP treatment time for the simultaneous preparation of SF and sericin. This one-step HTHP process provides a simple and efficient process for improving silk resource utilization and facilitating the industrial production of SF and sericin-based biomaterials.