Targeted and untargeted metabolites and antioxidant properties in chili pepper at different maturity stages

Chilies (Capsicum sp.) are popular for their pungency and nutrition; however, these parameters vary with harvesting maturity. The effects of maturity stages on secondary compound levels and antioxidant activities in “super hot” chilies were investigated. Seven maturity stages were selected (i.e., 100% green to overripe stage). The differences in overall compounds were examined at each maturity stage, including the capsaicinoid, total phenolic content (TPC), and total flavonoid content (TFC) levels and the antioxidant activities. Untargeted metabolic analysis revealed that the abundance of capsaicin and dihydrocapsaicin, the pungency factors, was the highest among compounds, irrespective of maturity stage. The same was observed for piperidine-containing compounds (e.g., piperidine propionic acid), which serve as an antidepressant and antioxidant agents. Targeted analysis showed that capsaicinoid levels in chilies increased from 100% green to 70% red stage, followed by a decrease and subsequent increase at the overripe stage. TPC was significantly the highest at the full red stage (13.51 mg GAE/g dry weight [DW]), whereas TFC was the highest at the 90% red stage (223.20 mg RUE/g DW). Regarding antioxidant activities, a decreasing trend was observed until the 90% red stage, followed by an increase thereafter. The capsaicinoid levels, antioxidant properties, and metabolites (e.g., 4-piperidinol) were highest at the 80% green stage. However, the full red stage had high levels of eugenin, a phenol with antioxidant properties, and was preferred by consumers. Thus, it is recommended that the 80% green stage could be used in pharmaceutical industries, whereas the full 100% red stage could be consumed fresh or cooked.