Two Types of Sericin Silkworm
There are two kinds of sericin silkworms. One is the naked pupa Nd strain, which secretes silk thread at a rate of 30 mg/head, with spinning and cocooning rates of 99%. The other sericin silkworm, the Nd-s strain, which secretes only a few silk threads, with a sericin content as low as 92%, at the cocoon stage. Hence, neither of the existing strains are practical for sericin extraction.
Efficient Production of Sericin
Therefore, it was necessary to develop a silkworm variety which produces sericin protein efficiently. It secretes silk thread, at the rate of about 80 mg/head, while the spinning and cocooning rates have been improved to 99%.
High Sericin Output
The output of the cocoon layer is over four times that of the Nd strain. Sericin can be very efficiently produced, because the sericin purity is as high as 98.5% at the cocoon stage.
Medical Use of Sericin
The sericin protein appears to be a functional material with antioxidative properties. It is expected to be of medical use in skin care and other fields.
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