Changes in bioactive compounds, antioxidant, and enzymatic activities in immature Cucurbita ficifolia fruit during postharvest storage

Abstract

Chilacayote (Cucurbita ficifolia Bouché) is a fruit rich in bioactive compounds; however, in its immature state, it is highly perishable. This limited shelf life requires the application of postharvest technologies, such as refrigeration. The objective of this study was to evaluate the changes in antioxidant content and enzymatic activity in immature C. ficifolia fruit during storage. Immature fruits were stored for 15 days at 5 and 10 ℃ [95% relative humidity (RH)] and room temperature (22 ℃, 83% RH). Weight loss, total polyphenols and flavonoids, ascorbic acid, and antioxidant activity were assessed every five days; phenolic compounds were identified by HPLC, and enzymatic activity was also monitored. The results indicate that the greatest weight loss occurred at 22 ℃ (9.2%). Concentration of total polyphenols and flavonoids was higher at 10 and 22 ℃ (0.24–0.27 mg EAG g⁻¹ FW and 0.061–0.076 mg ECAT g⁻¹FW, respectively). A decrease in ascorbic acid content was observed across all temperatures (averaging 17.1 mg EAA 100 g⁻¹FW). Higher antioxidant activity was recorded at 5 and 10 ℃ for FRAP (1.03 and 0.93 µmol Etrolox g⁻¹ FW, respectively) and at 10 and 22 ℃ for DPPH (1.5 and 1.3 µmol ET g⁻¹ FW, respectively). Four phenolic compounds were identified: p-hydroxybenzoic acid, p-coumaric acid, ferulic acid, and caffeic acid. p-Hydroxybenzoic acid (noted anti-inflammatory, antioxidant, antidiabetic, and antimicrobial properties) was the most abundant at 10 and 22 ℃. Furthermore, polyphenol oxidase (PPO) and peroxidase (POD) enzymatic activities were lower at 10 and 22 ℃ (0.047–0.060 U min⁻¹ g⁻¹ FW and 1.01–0.89 U min⁻¹ g⁻¹ FW, respectively). Consequently, a storage temperature of 10 ℃ is proposed to preserve the bioactive compounds of immature chilacayote for up to 15 days.

Keywords

Cucurbita ficifolia / postharvest / bioactive compounds / antioxidant activity / polyphenoloxidase / peroxidase

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