Phytochemical constituents and antioxidant capacity of different pecan [Carya illinoinensis (Wangenh.) K. Koch] cultivars

Six pecan cultivars were analyzed for their antioxidant capacity (AC), total phenolics (TP), condensed tannin (CT), HPLC phenolic profile, tocopherol and fatty acid composition. Kernels which included the outer brown testa or pellicle, and shells which is the hard cover that surrounds the kernel, were evaluated for each cultivar. Strong correlations were found in kernels between AC and TP for both DPPH (r2 = 0.98) and ACORAC (r2 = 0.75) antioxidant assays. ACORAC values ranged from 372 to 817 μmol trolox equivalents/g defatted kernel, corresponding to Desirable and Kanza cultivars, respectively. CT ranged from 23 to 47 mg catechin equivalents/g defatted kernel and TP from 62 to 106 mg of chlorogenic acid equivalents/g defatted kernel. After a consecutive basic-acid hydrolysis, gallic acid, ellagic acid, catechin and epicatechin were identified by HPLC. The TP, AC and CT were 6, 4.5 and 18 times higher, respectively, for shells compared to kernels. The presence of phenolic compounds with high antioxidant capacity in kernels and shells indicates pecans can be considered an important dietary source of antioxidants.