Comparative Study Between Orah Mandarin Peel and Traditional Mandarin Peels (Chenpi) Based on Data-Repository-Enabled Ultra-High-Performance Liquid Chromatography-Quadrupole-Orbitrap-Mass Spectrometry Analysis.

Orah mandarin is a new and hybrid fruit. Orah mandarin peel (OMP) and three traditional mandarin peels (TMPs, Chinese "Chenpi") were comparatively analyzed using data-repository-aided ultra-high-performance liquid chromatography-quadrupole-orbitrap-tandem mass spectrometry. The analysis has identified and quantified 52 compounds (including 35 phytophenols). Meanwhile, nine isomers were also distinguished, and 18 "unexpected" compounds were found in mandarin peels for the first time. Hesperidin was found to be the most abundant phytophenol in both OMP and three TMPs. All identified phytophenols were individually evaluated for antioxidant capacities. Their antioxidant percentages were further multiplied by the corresponding chemical contents to calculate the antioxidant contribution (AC) values. Ten phytophenols play a dominant role in AC in the whole peel and show similar distribution in the four peels. Thus, from the angle of antioxidant chemistry, OMP is similar to three TMPs and may serve as a potential functional food similar to Chenpi products (especially Guagnchenpi). Nevertheless, OMP can be recognized by some specific compounds (e.g., isofraxidin and xanthotoxin).