Analysis of Polyphenol Content and Antioxidant Capacity of Hybrid Mandarin Peel

Abstract

Mandarin cultivars (Citrus reticulata) represent 22% of the total number of citrus fruit crops. Mandarin peels are an abundant source of natural flavonoids and other antioxidants. To determine the polyphenol content and antioxidant capacity of hybrid mandarin peel, 33 samples of hybrid mandarins (Clemenvilla, Nadorcott and Ortanique), from the province of Valencia (Spain), were selected. Fresh mandarin peel extracts were prepared by ultrasound-assisted extraction (400 W, 80% v/v duty cycle, 40 °C) for 30 min, employing ethanol 50% (v/v) as the solvent in a 1:10 (w/v) solid–liquid ratio. C18 cartridges (200 mg) were employed for the solid phase extraction clean-up process, and an ultra-performance liquid chromatography system, coupled with a quadrupole time-of-flight mass spectrometer, was used to identify, and quantify the polyphenols. Clemenvilla and Ortanique showed the highest antioxidant capacity using DPPH and TEAC, respectively. For these three hybrids, the main polyphenol present in the samples was hesperidin, which was higher in the Nadorcott peel (72 ± 7.0 µg/g). Moreover, narirutin was higher in Ortanique and Nadorcott (33 ± 6.3 and 31.8 ± 6.8 µg/g, respectively), and rutin was higher in Clemenvilla samples (7.3 ± 3.8 µg/g). The results suggest that mandarin peels are an important source of polyphenol compounds with a high antioxidant capacity.

Keywords

• mandarin peel
• polyphenols
• hesperidin
• antioxidant capacity