Cold‐stored mulberry leaves affect antioxidant system and silk proteins of silkworm (Bombyx mori) larva

Abstract BACKGROUND Cold storage has been widely used to maintain the quality of vegetables, but whether eating cold‐stored vegetables affects health remains unknown. RESULTS This study used silkworms as an animal model to evaluate the effects of nutrient changes in cold‐stored mulberry leaves (CSML) on health. Compared with fresh mulberry leaves (FML), CSML contained lower vitamin C, soluble sugars and proteins, and higher H 2 O 2 , suggesting decreased antioxidant ability and nutrition. The CSML did not obviously affect larval survival rate, body weight or dry matter rate, cocoon shape, weight and size, or final rates of cluster and cocooning relative to the FML, suggesting CSML did not alter overall growth and development. However, the CSML increased the initial rates of cluster and cocooning and upregulated BmRpd3 , suggesting CSML shortened larval lifespan and enhanced senescence. CSML upregulated BmNOX4 , downregulated BmCAT , BmSOD and BmGSH‐Px and increased H 2 O 2 in silkworms, suggesting CSML caused oxidative stress. CSML upregulated ecdysone biosynthesis and inactivation genes and elevated ecdysone concentration in silkworms, suggesting that CSML affected hormone homeostasis. CSML upregulated apoptosis‐related genes, downregulated sericin and silk fibroin genes and decreased sericin content rate in silkworms, suggesting oxidative stress and protein deficiency. CONCLUSION Cold storage reduced nutrition and antioxidant capability of mulberry leaves. CSML did not influence growth and development of silkworm larva, but affected health by causing oxidative stress and reducing protein synthesis. The findings show that the ingredient changes in CSML had negative effects on health of silkworms. © 2023 Society of Chemical Industry.