Effects of Pre-germination Treatment on the Phytate and Phenolic Contents of Almond Nuts

Abstract

This study examined if pre-germination altered the water content and water activity, contents of phytate, total phenolic, (±)-catechin, quercetin and total antioxidant capacity of almond (<em>Prunus dulcis</em>)kernel. Raw almond kernels were submerged for 15 hours in water, 0.02 mol dm^-3 phosphate buffer solution (pH 5.0) and 0.02 mol dm^-3 phosphate buffer solution (pH 7.0) at 25 and 40ºC, respectively. The content and activity of water in the kernels before and after the pre-germination treatments were measured by oven drying and dew point water analysis, respectively. The total phenolic and phytic acid contents of the kernels were quantified by using Folin-Ciocalteu and a published spectrophotometric assay, respectively. (±)-Catechin and quercetin contents in the almond kernels were determined using gas-chromatography mass spectrometry. The total antioxidant capacity of the kernels were measured by 2,2'-diphenyl-1- picrylhydrazyl assay. Treatment with water, PBS pH 5 and PBS pH 7 significantly increased the water, total phenolic, (±)-catechin contents and total antioxidant capacity of the almond kernels regardless of the treatment temperatures (25 or 40°C). The phytic acid and quercetin contents were significantly elevated after the three treatments at 40°C. The total phenolic, (±)-catechin, quercetin and phytate contents in the almond kernels contributed significantly to its antioxidant property. Our results suggested that the phytochemical compositions of the almond kernels changed during pre-germination. The temperature and pH of the medium exert differential influence on the phytochemical compositions of the pre-germinated almond kernels.