Multidimensional Analysis of Silkworm Cocoons Produced with Different Feeding Diets

Artificial diets are increasingly utilized in sericulture, yet they often yield cocoons with properties that differ from those produced by mulberry leaf-fed silkworms. A reliable method to distinguish between these two types of cocoons remains lacking, compromising quality control in silk-related industries. In this study, we report a multidimensional analysis method integrating chemical, structural, and biomarker analyses to distinguish cocoons produced by mulberry leaf-fed (Mul-fed) silkworms from those produced by artificial diet-fed (Art-fed) silkworms. The SEM images showed that after the process of biomarker extraction, Mul-fed cocoons had a more complete morphological structure than Art-fed cocoons, and the sericin layer of Mul-fed cocoons was less damaged. Thermogravimetric and amino acid analyses revealed no significant differences between the two types of cocoons. Biomarker analyses via ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) revealed that quercitrin and quercetin were enriched in Mul-fed cocoons, while daidzein and genistein were enriched in cocoons produced by artificial diet-fed silkworms. Furthermore, materials extracted from Mul-fed cocoons demonstrated significantly superior bioactivity than those from Art-fed cocoons in in vitro assays. This study provides a reliable and accurate method for assessing cocoon quality and distinguishing cocoons from different feeding methods, laying a robust basis for quality evaluation and silk product development.