Effects of roasting conditions on sensory attributes, polyphenolic content and DPPH radical scavenging activity of peanut (Arachis hypogaea)

Roasting is considered the commonest processing method applied to foods, it affects both phytochemicals and sensory attributes. In the present study, the effect of varying roasting parameters on sensory attributes was determined, as well as scavenging property against free radicals (DPPH) and polyphenolic content (TPC and TFC) of whole peanut kernels. Whole peanut kernels were roasted at different temperatures (130-150 °C) with various durations (5-20 min). Finding revealed that peanuts roasted at 130, 140, and 150 °C for 15, 10, and 5 min, respectively, received significantly the highest (p<0.05) sensory scores in all the parameters investigated. Therefore, they were selected for TPC, TFC, and DPPH assays. All three assays were found to increase during roasting compared to the unroasted counterpart. Peanuts that were roasted at 140 °C for 10 min, had the highest total phenolic contents of 67.26 ± 1.77 mg GAE/g while those roasted at 150 °C for 5 contained the highest TFC of 12.91 ± 0.56 mg QE/g. The highest DPPH radical scavenging activity was detected in the sample roasted at 140 °C for 10 min with an IC50 value of 417.44 μg/mL. Roasting significantly affected the bioactive contents as well as the scavenging activity of the whole peanut.