Comparison of Phytochemicals and Antioxidant Capacity in Three Bean Varieties Grown in Central Malawi

The aims of the current work were: (1) to study the influence of variety and geographical production area on the total phenolic content, total anthocyanin content, total flavonoid content, total carotenoid content and antioxidant activity in bean varieties (Dimeta, Napirira and Nanyati) from different growing areas in central Malawi, and (2) to evaluate the possibility of establishing a classification based on the geographical areas of the growing regions. A total of 47 bean samples were collected from Makowe, Mphathi, Chuma-Chitsala and Khulungira Zone. These four locations were segregated based on altitude, latitude and longitude. Principal component and hierarchical cluster analysis were used to distinguish and classify among these samples. Significant differences (P < 0.05) in total phenolic content (2.92-4.97 mg/g), total anthocyanin content (14.52-152.31 mu g/g), total flavonoid content (2.01-6.38 mg/g) and oxygen radical absorbance capacity (16.75-24.51 mu mol/g) were found among the different sampled villages, showing a significant effect of the producing region on these parameters. The beans in Makowe had lower polyphenols than in other locations. Results of principal component analysis indicate that phytochemicals and antioxidant capacity could serve as parameters to establish a bean classification according to the geographical area of production.