Studies On The Technologies Of Male Silkworm Cocoon Drying And Cooking

The demonstration and extension of male silkworm varieties greatly enhance the traditional sericulture industry, which substantially increased the economic benefits of sericulture. But it is only in recent years specially to rear male silkworms and to achieve scientific and technological achievements, related techniques of cocoon drying and cooking fail to keep up, It is still used that the old technologies of cocoon drying and cooking designed for mixed cocoons of male and female silkworms in the production with the result that it is difficult to reel high-quality raw silk from high quality cocoons of male worms, such as over dried cocoons and lower reelability percentage, which affect the large scale spreading of male silkworms. According to the characteristics of male silkworm cocoons, this study targeted to carry out a series of cocoon drying and cooking trials for the cocoons from male silkworms based on the investigation and comparison of cocoon quality difference between the male silkworms and conventional worm varieties, and proposed a suitable technology conditions for male silkworm cocoon drying and cooking, to raise the male worm's cocoon processing technology in order to provide reference. The main findings are as follows.1. Mastered the quality characteristics of male worm's cocoons that were:compared with conventional varieties, the cocoons of male silkworm varieties were lower cocoon weight, higher cocoon shell percentage (all more than 23%),higher cocoon drying ratio, thicker cocoon shell and more uniform, and evener cocoon width among the cocoons; lower cocoon shell weight than that conventional varieties in spring, and hither than that conventional varieties in autumn; the dried and fresh weight or water content of pupa were significantly less than that of conventional varieties and water content rate of fresh cocoon shell was relatively close to both..2. Understanding the drying characteristics of the male worm's cocoons, drawing comparison chart of constant temperature drying curve, graph shown that male worm's cocoon drying process was faster than that conventional varieties both for spring and autumn.3. Identified the drying rate of suitable dried cocoon shell, of which the standard for conventional varieties could be used for the male silkworm cocoons, that was 95% and the drying rate of suitable dried pupa to use the new standard that was 32%±1%, in order to calculate the theoretical drying rate of suitable dried cocoons for male silkworms, providing the basis to dry the male worm's cocoons till suitable dried. 4. Raised drying technological conditions for male silkworm cocoons:that the existing technologies and equipments for the cocoons of conventional varieties could also be applied for the cocoons of male silkworm varieties, but compared with the conventional variety, when male silkworm cocoons are dried, the dehumidification should be reduced, the drying time should be shorted and the cocoon amount in every tray could appropriately be increased. It is recommend for the operation that twice dried method was adopted, cocoon amount put in the trays was 4.8kg/m2 5.5kg/m2, the temperature was 100℃and the drying time was about 2h20min and 2h40min for first drying under the consideration of the existing conditions of the actual production of cocoon drying station; for the second drying, the variable temperature method was adopted, the drying time was about 3h and actual duration time would be determined by the combination of pupa test.5. Detection of skein content and percentage of the male silkworm cocoon shell, shown that the skein percentage of male silkworm hybrid Qiufeng×Ping28 was in the range between 24.50%-27.55%, which was lower than that of control hybrid Jinsong×Haoyue under the same rearing conditions.6. Proposed the male silkworm cocoon cooking technological conditions under the pot cooking condition:that was not suitable for immersion approach before cooking process. Appropriate extension of cooking time during the periods of the high temperature replacement and the low water absorption could help to improve reelability, but that would be resulting in reducing raw silk rate resulting from large loss of skein dissolved. Combined with the characteristics of lower skein content and thicker cocoon shell of male worm's cocoons, suggestions appropriate to extend the low temperature absorption phase of the processing time, reduce the cooking time of adjustment phase, the specific time duration could be determined according to the reelability percentage and raw silk ratio of the cocoons. Based on the present study of cocoon quality of male silkworm hybrid Qiufeng×Ping 28, we recommend that the heat treatment temperature should adopt the 98℃, the processing time would be lmin, the temperature for low temperature treatment should be 65℃and duration time should be 5min, and the total cooking time should be controlled around the 11-13min as well.