Study On The Cryopreservation Of Fresh Cocoon

The fresh pupa rich in essential nutrients and ingredients,widely used in the field of medicine and food,bring good economic benefits.When the fresh cocoon is concentrated on the market,it is necessary to store the fresh cocoon at low temperature during the process of reeling.In view of the casual phenomenon of low temperature preservation technology in silk industry,the low temperature preservation process of fresh cocoon was studied.How to preserve fresh cocoon,to meet the production of fresh cocoon silk reeling and to ensure the quality of fresh pupa is a subject worthy of study.In order to explore the cryopreservation process of fresh cocoon,5 different preservation temperatures were designed,which were 0 ?,-5 ?,-10 ?,-20 ? and-30 ?,respectively.4different preservation days were 10 days,25 days,40 days and 60 days respectively.To test and analyze cocoon quality,permeability of cocoon layer,structure of silk and silk shape of fresh cocoon after cryopreservation and dried cocoon,fresh cocoon of the control group.The results show that low temperature preservation is beneficial to increase the reelability rate and the length of reelable silk,and the number of times of roughness per 10000 meters is less than that of dry cocoon.The water contact angle value of cocoon layer decreased after cryopreservation of fresh cocoon at low temperature,the penetration of cocoon layer is improved,improvement of penetration uniformity of cocoon layer,and the stripping tension value and fluctuation amplitude of cocoon silk decrease,especially the inner cocoon silk stripping tension value decreased significantly.After cryopreservation,the number of thread dropping decreased,and the number of thread dropping in inner layer decreased obviously.Low temperature preservation of fresh cocoon can improve the production and stand ability of automatic silk reeling.The low temperature preservation temperature and preservation time of fresh cocoon have great influence on the quality of pupa body.When the preservation temperatures were 0 ?,-5 ? and-10 ?,the rate of good pupa decreased obviously with the prolongation of the preservation days.The cryopreservation time should not exceed 10 days,when the preservation temperature is between 0 ? and-10 ?.The cryopreservation temperature below-20 ? can be kept for a long time,and the pupa body is basically not metamorphosed.The results of X-ray diffraction,Fourier transform infrared spectroscopy and scanning electron microscope analysis of the fresh cocoon silk preserved at low temperature show that there is no change in the structure of cocoon silk of the cocoon after cryopreservation,and thereis still the ?-helical structure,?-folding structure and the uncurving structure in the cocoon filament,and the structure is dominated by the ?-folding structure.After cryopreservation,smaller voids and cracks will occur in some parts of cocoon filaments.Through the analysis on the cryopreservation of fresh cocoon of cocoon quality and cocoon layer inspection penetration effect and structural properties of silk,comprehensive results show that low temperature preservation of fresh cocoon can not only solve the preservation problem of fresh cocoon,but also improve the reelability,reduce the number of thread,the effect of cocoon layer inspection penetration is better,and the structure of cocoon silk does not change.To keep fresh pupa fresh and not affect cocoon quality,it is suggested that the preservation temperature is between-20 ? and-30 ?,and the number of preservation days is not more than 40 days.