Effect of Cooking methods on Total Phenolics and Antioxidant activity of selected wild Edible plants

Abstract

The objective of this assessment was to investigate how different cooking techniques, such as boiling and microwave cooking, impact the levels of total phenolics and antioxidant activity in commonly consumed plants like Perilla ocymoides, Clerodendrum colebrookeanum, Solanum gilo, Solanum kurzii, and Potentilla lineata, prevalent in the North-Eastern region of India. To measure the antioxidant properties of these plants, various methods were employed, including 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity, ABTS radical scavenging ability, reducing power capacity, and the assessment of total phenolic, flavonoid, and flavonol contents. The analysis revealed that the total phenolic content (TPC) of fresh vegetables ranged from 77.47 to 797.68mg/100g (expressed as gallic acid equivalent) on a dry weight basis. The total antioxidant capacity of fresh plants, measured as the percentage of inhibition, varied between 7.62% and 83.44% for DPPH, and 12.22% to 79.46% for ABTS. Boiling emerged as the cooking method causing the greatest reduction in TPC, resulting in a decline ranging from 10.90% in P. lineata up to 25.66% in S. kurzii when calculated on a dry weight basis. Conversely, microwave cooking led to an enhancement in TPC, with an increase ranging from 2.20% to 11.80%. Furthermore, the impact of boiling on DPPH radical scavenging activities was notable, causing a decrease between 8.44% and 43.30%, and for ABTS radical scavenging activities, the reduction ranged from 10.24% to 34.45%. In contrast, microwave cooking had a positive effect on DPPH and ABTS radical scavenging activities, increasing them by 9.39% to 46.32%, and 8.49% to 46.39%, respectively, across the studied plants. In conclusion, the results suggest that microwave cooking stands out as the optimal method for preserving and even increasing the concentration of polyphenols and antioxidants in these plants. Conversely, boiling exhibited the least desirable outcomes in terms of retaining these beneficial components.