The present work evaluates the potential of hazelnut kernels as a source of antioxidants to be incorporated
into new products. First, the effects of extraction conditions on the isolation of hazelnut kernels’ total
phenols and antioxidants were evaluated. Six conditions, involving different solvents (water, methanol
and aqueous acetone) and contact times, were studied. The highest total phenol contents were obtained
with boiling water for 30 min, 44.3±7.7mgGAE/gextract, and 80% (v/v) aqueous acetone solution for
24 h, 36.2±8.8mgGAE/gextract. Increasing the contact time for the acetonic extractions did not improve
the total phenols content. Regarding antioxidant activity, the highest DPPH-scavenging effect value
was obtained with 80% (v/v) aqueous acetone for 24 h with an effective concentration (EC50) equal to
1.12±0.07 mg/mL. When other nuts – walnuts, almonds, pine nuts and peanuts – were extracted under
this condition, only walnut extract exhibited higher phenol content (268±32mgGAE/gextract), antioxidant
activity as measured by reducing power (EC50 = 0.091±0.015 mg/mL) and free radical scavenging
capacity (DPPH assay) (EC50 = 0.060±0.010 mg/mL) than hazelnut extract. The present work demonstrates
that some nuts might be a natural source of bioactive compounds that can be incorporated into
new health-related products or be substitutes of synthetic compounds of questionable safety, promoting
human health and reducing disease risks.
