Chlorophyll and Carotenoid Degradation in Pepper (Capsicum spp.): Pathways, Mechanisms, and Postharvest Implications

Pepper (Capsicum spp.) is a globally significant crop with extensive economic and nutritional value. The degradation of chlorophyll and carotenoids, the primary pigments responsible for fruit coloration, directly impacts postharvest quality and processing stability. However, current knowledge of pigment degradation in pepper fruits remains fragmented: the molecular identities of key chlorophyll catabolic enzymes (e.g. Mg-dechelatase) are still elusive, direct functional evidence for specific carotenoid cleavage dioxygenases (CCDs) and lipoxygenases (LOXs) in Capsicum is limited, and an integrated analysis of concurrent chlorophyll and carotenoid degradation pathways is lacking. This review systematically fills these gaps by comparing the enzymatic (PAO pathway for chlorophylls; CCD/LOX-mediated for carotenoids) and non-enzymatic (ROS, light, pH, metal ions) degradation pathways specifically in pepper. We further evaluate external drivers—including agricultural practices, postharvest handling, food processing technologies, and environmental stressors—and discuss emerging tools such as multi-omics and CRISPR-Cas9 as promising strategies to regulate pigment degradation. By synthesizing these advances, this review provides a comprehensive foundation for future research aimed at preserving pepper quality, reducing postharvest losses, and improving storage stability through integrated, interdisciplinary approaches.