Establishment Of HPLC Fingerprint Structure For Fresh Cocoon/Dry Cocoon Raw Silk

In the production of raw silk,the cocoon of fresh cocoon raw silk is not dried,and reeling is carried out directly in vacuum infiltration.The raw silk reeled by cocoon drying and cocoon cooking is called dry cocoon raw silk.Silk is composed of a variety of proteins,including polyphenols,esters and other trace components.When different reeling processes are used,the protein structure of raw silk and the trace components in raw silk will change.Therefore,different types of raw silk have certain differences in adhesion,stretching,cleanliness and other properties,which is not conducive to the quality management of raw silk products.Traditional silk weaving enterprises usually use dry cocoon raw silk as the main raw material for production.However,due to the less fresh cocoon reeling process and relatively less energy consumption,it has been rapidly promoted in recent years and its proportion in the market has been expanding.As a result,the types of fresh cocoon raw silk and dry cocoon raw silk products on the market are mixed and difficult to distinguish,which causes trouble to the raw material procurement and production arrangement of silk weaving enterprises.Therefore,it is necessary to distinguish fresh cocoon / dried cocoon raw silk.In this paper,high performance liquid chromatography was used to obtain the trace component information of fresh cocoon / dry cocoon raw silk from different sources.Through the extraction and analysis of the trace component information of raw silk,the HPLC fingerprints of fresh cocoon / dry cocoon raw silk were established respectively to identify the types of raw silk.At the same time,the effects of various internal and external environmental factors and processing and storage conditions on the trace components of raw silk were also explored.The results are as follows :(1)Fresh / dried cocoon raw silk samples from different sources were tested by HPLC to analyze the effects of biological and regional factors on the trace components of raw silk.The chromatographic peak area of raw silk samples was used as a variable factor to explore the influence of various factors on the trace components of raw silk.The results of similarity evaluation and cluster analysis showed that silkworm eggs and feeding methods had significant effects on the trace components of raw silk,while cocoon period and origin had little effect on the trace components of raw silk.The results of orthogonal partial least squares discriminant analysis showed that silkworm egg was the most important factor affecting the trace components of raw silk,and the trace components that contributed greatly to the difference in the characteristics of fresh/ dry cocoon raw silk components were concentrated between 8.80 and 17.43 min.(2)According to the HPLC fingerprint data of raw silk from different sources,the HPLC fingerprint of fresh / dried cocoon raw silk was constructed.Different classification methods were used to verify the identification effect of HPLC fingerprints.According to the common fingerprint of HPLC,there were five common characteristic peaks in fresh cocoon raw silk,which were 1.70 min,5.90 min,8.69 min,10.32 min and 14.59-16.50 min,respectively.There were two common characteristic peaks in dry cocoon raw silk,and the retention time was 1.70 min and 5.64 min,respectively.According to the similarity evaluation,the similarity of fresh cocoon raw silk samples is greater than 0.861,the similarity of dry cocoon raw silk samples is greater than 0.987,and the characteristics of similar raw silk are similar.Cluster analysis and discriminant factor analysis showed that the two types of raw silk could be classified by HPLC fingerprint.The methodological verification showed that the fingerprint had good reliability and repeatability in the determination of trace components of raw silk.(3)The effects of baking treatment and storage conditions on the characteristics of trace components of fresh / dry cocoon raw silk were investigated.The results show that the total phenolic content of cocoon filaments is significantly reduced by baking and boiling in the reeling process.The trace component characteristics of cocoon filaments treated only by baking or boiling are different from those of fresh cocoons and dried cocoons,while the trace component characteristics of cocoon filaments treated by baking and boiling are similar to those of dried cocoons.It can be seen that the difference in trace components of fresh cocoon / dry cocoon raw silk is caused by the combined action of baking and boiling treatment during silk reeling.The results of storage conditions showed that the total phenolic content in raw silk decreased gradually with the increase of storage time of raw silk or frozen storage time of living pupae cocoon as raw material for reeling,but the trace component characteristics of raw silk did not change.