Chemical and physical properties of cocoon filaments from various races

In response to the Silk industry's demand for disease-resistant strains of Bombyx mori silkworms, as well as filament fineness determined by strain, new strains were breed to answer the request. This study considers the chemical and physical properties of the silk fibers from the resultant strains of Bombyx mori. Silk fibers from various race of silkworms were evaluated for variations in physical and chemical properties in addition to visual evaluation. The percent of sericin, water content, reelability and size/shape of cocoons were all similar. Some strains had different amounts of water retained in the cocoons after drying. The fineness of the fibroin filaments was not very different between the strains. Strains that extruded filaments with small figure 8 motions were more difficult to reel. These samples show slight variations in physical properties and visual evaluation between each samples but show similar compositions for all the races. All the strains extrude fibroin with essentially the same amino acid composition, thus all domesticated silks are compositionally equivalent. The X-ray diffraction patterns of the silk fiber bundles indicate similar lattice coordinates, or unit cells for all the strains observed. The Fraunhoffer diffraction patterns of seemlier weave construction fabrics from the various strains were also equivalent. The yellow cocoon of the "Ohaku" strain was determined to rapidly yellow under ambient conditions