Ascorbic acid, capsaicinoid, and flavonoid aglycone concentrations as a function of fruit maturity stage in greenhouse-grown peppers

• Effects of cultivar, growing season, maturity on pepper bioactive compounds studied.
• Ascorbic acid and flavonoids highest in mature paprika-type pepper cultivars.
• Capsaicinoids higher in mature Ixtapa and Mesilla pepper cvs.
• Total phenolics and antioxidant activity moderately correlated in mature peppers.
• Genetic variability, cultivation: useful bases for improving pepper composition.

Bioactive compounds in plant-derived foods provide essential human health benefits. However, the content and types of bioactive compounds may vary based on genetic and environmental factors. The present study examined the impacts of cultivar, fruit maturity stage (mature versus immature), and growing season (2008, 2009) on the concentration of bioactive compounds in diverse pungent and non-pungent peppers. Significant interactions were observed among cultivars, maturity stages, and growing seasons. Mature peppers generally had the highest content of ascorbic acid (782.0–2305.3 μg/g FW in 2008 and 693.5–2817.2 μg/g FW in 2009), and capsaicinoids (115.5–338.9 μg/g FW in 2008 and 93.8–326.3 μg/g FW in 2009) compared to immature peppers. Paprika-type peppers generally had the highest contents of ascorbic acid and flavonoids especially in mature fruits, while capsaicinoids were higher in all mature stage peppers. Flavonoid concentrations varied considerably depending on cultivar and maturity stage. Total phenolics were also significantly higher in mature fruits compared to immature peppers in both years. A positive correlation between total phenolics and DPPH radical scavenging activity was observed. This indicates that the health beneficial components in peppers could also vary as a function of cultivar, fruit developmental stage and production season. The genetic variability in bioactive compounds found in this study constitutes a useful genetic base for improving the nutrient quality of peppers.