Cultivar and E-Beam irradiation effects on phytochemical content and antioxidant properties of pecan kernels

Abstract

Pecan kernels from six cultivars were analyzed for phenolic content and antioxidant properties. In addition, kernels from two cultivars were irradiated with 0, 1.5 and 3.0 kGy using E-Beam irradiation and stored in accelerated conditions (40 °C and 55% R.H.). Changes in phytochemical profile and antioxidant properties were monitored for 134 days. Cultivars differed greatly in their phytochemical content. Total extractable phenolic content (TP) ranged from 62 to 106 milligrams of chlorogenic acid equivalents per gram of defatted kernel. Antioxidant capacity (AC) measured by the DPPH free radical had a strong correlation with TP. Shells from each cultivar were 6, 4.5 and 18 times greater for TP, AC and condensed tannin content (CT). Gallic and ellagic acids, epicatechin and catechin were identified in hydrolyzed extracts of all cultivars. Prior to hydrolysis, no compounds were positively identified. Fatty acid profile of kernel oil had a strong inverse correlation between oleic and linoleic oil. Kernels from the same cultivar but different location differed in their fatty acid composition but had similar TP. Irradiation of â Kanzaâ and â Desirableâ kernels with 1.5 and 3.0 kGy had no detrimental effects on AC and TP by the end of experiments. Phenolic profile was similar for all treatments. Tocopherol content decreased with irradiation treatments, but no further degradation was observed throughout storage. Peroxide values increased slightly after 98 and 134 days of storage for â Desirableâ kernels, with slight differences between controls and irradiated samples. Color of kernels decreased in lightness and yellowness and increased in redness with no differences between irradiated samples and controls. For the first time the effect of pecan cultivar and E-Beam irradiation was assessed in phytochemical and antioxidant attributes of pecan kernels. Additionally, irradiation with E-Beam had no significant detrimental effects in phytochemical composition and only a slight increase in peroxide value, indicating potential as pecan kernel sanitization.