Antioxidant characteristics of different solvent extracts from almond (Prunus dulcis L.) shell

Abstract

The extracts from almond (var. katha badam and kaghzi badam) shell, produced by different extraction solvents (80% methanol, 100% methanol, 80% ethanol, and 100% ethanol), were investigated for their antioxidant activity and total phenolic (TP) contents. Antioxidant activity (AA) of the extracts was determined by measuring the reducing power, inhibition of linoleic acid peroxidation and 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) scavenging capacity. The shell extracts exhibited considerable amount, ranging from 1.36 to 7.21 mg, gallic acid equivalents (GAE) /100 g of dry matter, of total phenolics. The reducing power (absorbance data at 12.5 mg/ml extract concentration) ranged from 0.31 to 1.83 while inhibition of linoleic acid peroxidation and DPPH radical scavenging capacity varied over 38.22 to 82.80% and 12.15 to 57.90%, respectively. The present results showed significant (p  80% ethanol >100% methanol > 100% ethanol. These results support the potential uses of almond shells (an agrowaste) for the isolation of antioxidants which could be explored for food preservation and pharmaceutical uses.   Key words: Almond shell, solvent extraction, antioxidant components, total phenolics, linoleic acid peroxidation, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical.