Extraction of antioxidants from almond-processing byproducts.

Abstract

In this work, 8 different solvents/mixtures have been tested for the extraction of antioxidants from by-products derived from the industrial processing of almonds (skin or seed coating, brown hull, and green shell cover or mesocarp). The oxygen radical absorption capacity (ORAC) as well as the phenolics content of the extracts has been determined. The extracting solution methanol/HCl (1000:1, v/v) was the most effective for the almond skin and shell, whereas, for the hull, it corresponded to acetone/water (50:50, v/v), resulting in ORACFluorescein values of 0.467, 1.45 and 0.0504 mmol of Trolox/mg, respectively. At the same time, the mixtures acetone/water exhibited the highest content of total polyphenols and proanthocyanidins for the three by-products studied. Finally, results have shown that the by-products derived from almond processing, in particular, the skin and shell, posses a similar antioxidant capacity to that of grape by-products which are currently used in the development (or production) of antioxidant products.

Keywords

• almonds
• antioxidants
• orac-fluorescein
• polyphenols
• proanthocyanidins