Silk reeling of silkworm cocoon in strongly alkaline electrolyzed water as a sericin swelling agent at low temperature

Strongly alkaline electrolyzed water (SAEW) was used as a sericin swelling agent for silk reeling from cocoons of the silkworm Bombyx mori. Tap water was electrolyzed with a laboratory-made combined water electrolyzer to generate SAEW with pH 11.50. The hardness of SAEW was 30% less than that of the tap water, whereas the concentrations of Na+ in SAEW were 18% higher than those in the tap water. The pH of the SAEW was stable for at least a month in an airtight container. Cocoons were immersed in pH 11.50 SAEW for 15 min with shaking, which replaces one step of the complex cocoon cooking process in the traditional reeling method (TRM) where penetration is achieved by repeatedly alternating high and low temperatures. The swollen cocoons were transferred into fresh pH 11.50 SAEW for reeling at the same, or slightly lower, temperature. The sericin loss from the whole cocoon in pH 11.50 SAEW is about 3.5% and the tensile property of the single silk fibroin filament is similar to or better than that of TRM. Silk reeling in SAEW involves only one step of cocoon swelling in pH 11.50 SAEW (70°C), which replaces a series of complex processes including water penetration, water absorption, swelling, and then silk reeling in the TRM. A novel low-temperature and simple reeling technology suitable for development by the silk industry is described.