Cocoon Appearance Characteristics

The external symptoms of silkworm cocoons that can be observed by the naked eye are part of the characteristics of silkworm cocoons, which mainly include four items: cocoon shape, cocoon color, cocoon layer tightness and cocoon layer shrinkage.

The morphology of silkworm cocoons varies greatly depending on the silkworm species. Silkworm cocoons usually have oval, tunic, spherical, oval and spindle shapes. The cocoon shape is determined by the habit and body shape of silkworm species when spinning, and it is inherited. The cocoons of Chinese silkworm varieties are elliptical, spherical and oval; Japanese silkworm varieties are elliptical in a deep girdle shape; European silkworm varieties have long elliptical cocoons and have a shallow girdle shape; Guangdong and southern China have more diversified cocoons. It is fusiform. The first generation of hybrid cocoons are in the middle of their parents. Most of the silkworm cocoons produced in the rural areas of China in modern times are mostly hybrid cocoons of the Chinese and Japanese generations, which are elliptical and micro-waisted. The size of cocoon grains varies depending on the variety and production period, etc., measured by the number of cocoons per liter, about 65 to 95 grains. Deformed cocoons can also occur due to the health of the silkworm body and the different methods of stalking or stalking.

The color of silkworm cocoons also varies from species to species. There are many cocoon colors such as white, yellow, pink, creamy yellow, light yellow green (light bamboo blue), green and its intermediate colors. The same hue is also dark and light. Although the pigment of the cocoon comes from the plant pigment of the mulberry leaf, the digestive tract and the silk gland of the silkworm differ in their ability to penetrate the pigment due to different silkworm species. Therefore, different species of silkworms will produce different results if they eat the same mulberry leaf. Color cocoons. Usually the cocoon layer of yellow cocoons contains lutein, red cocoons or cream yellow cocoons contain carotene, light bamboo blue cocoons or green-yellow cocoon pigments, lack of carotenoids or have a minimal content of white cocoons. The color of the cocoons is hereditary. In China, there are many white cocoons and yellow cocoons. Diversified cocoons include light bamboo blue cocoons and green cocoons; Japanese cocoons are mostly white cocoons, but also yellow cocoons, green cocoons, etc.; European cocoons include creamy yellow, white, yellow, and pink cocoons. The white cocoons produced in rural China are all hybrid white cocoons of the Chinese and Japanese generations, and some are slightly bamboo-blue and brown-beige. Colored cocoon species, the color of the cocoon raised at high temperature is dark, and the color of cocoon raised at low temperature is light, the cocoon formation environment is wet, and the color of the cocoon is dark. The pigment of colored cocoons mainly exists in cocoon sericin. After degumming and refining, it can generally become white. However, the green cocoon pigment and sericin silk fibroin are both present, and it is not easy to remove it only by degumming. Fluorescence occurs when the cocoons are irradiated with ultraviolet rays. The color of the fluorescence varies from cocoon: white cocoons are yellow, purple, and their intermediate colors. The yellow cocoons are bright yellow, dark yellow and their intermediate colors. The fluorescence that occurs on the cocoon layer is all yellow or purple, some yellow, and some purple is a mixture of purple and yellow. The fluorescent color of the cocoon is related to its unwinding performance. In the same silkworm species, the yellow fluorescent cocoon unwinds better, the purple fluorescent cocoon unwinds poorly, and the unwinding mixed with purple and yellow is somewhere in between.

The degree of density of the cocoon layer structure. In addition to the variety factor, depending on the climatic environment of the cocoon when forming the cocoon, the cocoon layer will be soft when the cocoon is formed under high temperature and dryness or strong wind. In the former, the cocoon silk is easy to cut when reeling, which relieves the bad. The latter cocoon has many ring knots and sliver knots, and the cocoons are prone to over-cooking.

Wrinkles appearing on the outer part of the cocoon. After the first cocoon layer formed by the mature silkworm dries, when the cocoon layer formed close to it dries and shrinks, the dried outer layer shrinks. Usually the outer layer shrinks deeply and becomes shallower toward the inner layer until smooth and wrinkle-free. The shrinkage is also different due to different varieties. The shrinkage of the cocoon is rough and hard in a humid environment, and the shrinkage of the cocoon is loose and floating in an excessively dry environment. Rough and uneven relief, many loose and soft shackles.