Preservation of silkworm cocoons - by treating with methyl bromide and drying with hot air

摘要

Preservation of silkworm cocoons is effected by (a) contacting the cocoons for 10-60 min. with an air stream contg. 40-150 g/ cubic m of methyl bromide and having a moisture content of 10-30 g/kg, and (b) drying the cocoons by contacting for 120-180 min. with an air stream having a temp. of 70-140 deg.C and a moisture content of 100-180 g/kg. The contact time in step (a) is pref. 10 min. when the air contains up to 150 g/cubic m of MeBr and 10 g/kg moisture, or 60 min. when the air contains 40 g/cubic m of MeBr and 20 g;kg moisutre. moisture. The contact time in step (b) is pref. 180 min. when the air is at 100 deg.C and contains 120 g/kg moisture, or 120 min. when the air is at 140 deg.C and contains 130 g/kg moisture. In step (b), the air temp. is pref. gradually decreased at a rate of 10-35 deg./hr. while the moisture content of the air is increased at a rate of 20-40 g/kg. The process can be operated continuously with a high throughput and low energy consumption. The treated cocoons can be stored for long periods (e.g. 12-24 months) and give high yields of raw silk.