2024 Volume 32 Pages 11-19
The multi-band progressive type of cocoon drying machine is a hot air-drying method commonly used for cocoon drying. It is recommended that a hot air-drying temperature at 115 ˚C be used in contact with the cocoon. Thereafter, the finishing temperature should be gradually reduced to 60 ˚C. However, in this study, the harvested cocoons were dried at 60 ˚C for 24 hours because high temperature treatment usually causes the fluorescent color to disappear. Therefore, we considered introducing an air-heated decompression dryer, which is used in the production of dried persimmon, “Ichida-gaki,” to improve the efficiency of cocoon drying. The results of drying white cocoons using an air-heated decompression dryer showed that the yellow index was significantly low, and the discoloration caused by heat was suppressed to a considerable extent. Furthermore, the result of drying green fluorescent cocoons, which are genetically modified silkworms, using the air-heated decompression dryer showed that discoloration was prevented to a considerable extent. Regarding constant drying at 60 ˚C, low temperature drying without decompression required 24 hours of drying, whereas decompression drying reduced the drying time to 14 hours; this is expected to improve the cocoon processing efficiency.
