Investigation of the antioxidant capacity and phenolic constituents of U.S. pecans

• A variety of phenolic compounds were identified in 18 U.S. pecan cultivars by HPLC-ESI-MSn.
• The antioxidant activity of pecan cultivars stems from their phenolics and tocopherol contents, which were quantified.
• Alkaline and acid hydrolyses of phenolics assisted with the identification of compounds in the pecan samples.
• Ellagic acid and its derivatives dominated the phenolic profile of pecans.
• Our findings reported here greatly enrich the phenolics database of pecans.

The content of phenolics and their antioxidant capacity were determined in 18 U.S. pecan cultivars. Acetonic crude phenolic extracts were prepared, fractionated and then their antioxidant capacity and phenolic contents assessed. H-ORACFL and FRAP values ranged from 13.5 to 25.5 mmol Trolox eq/100-g nutmeat and 14.0 to 20.7 mmol Fe2+ eq/100-g nutmeat, respectively. The total phenolics contents varied from 1.82 to 2.62 g ellagic acid eq/100-g nutmeat, while the total procyanidins contents (TPrC) were determined to be 420 to 655 mg procyanidin B2 eq/100-g nutmeat. The dominant phenolic compounds included gallic and ellagic acids, their derivatives, and proanthocyanidins. As confirmed by tandem HPLC-ESI-MS, no new aglycones were liberated from soluble esters and glycoside-bound phenolics after base and acid hydrolysis, respectively.