Effect of processing methods on polyphenols content of red, white and black kidney beans

Serkalem Abera, Weldegebriel Yohannes and Bhagwan Singh Chandravanshi

Abstract

This study was aimed to evaluate the effects of processing methods on total phenolic compositions of red, white and black kidney beans cultivated in Ethiopia by UV-Visible spectrophotometry. The polyphenol contents were found to be 48, 99 and 193 mg/100 g in the raw, soaked and cooked red kidney bean samples, respectively. It showed 51.3% increment during soaking followed by 48.5% increment upon cooking. The polyphenol contents were found to be 45, 83 and 182 mg/100 g in the raw, soaked and cooked white kidney bean samples, respectively, which showed 45.6-54.2% gaining of polyphenol content during soaking followed by cooking. The polyphenol contents of black kidney beans were found to be 43, 95 and 190 mg/100 g in the raw, soaked and cooked samples, respectively, showing the increment of polyphenol during soaking 50.0% followed by 45.2% upon cooking. The results were analyzed using an ANOVA and Tukey’s test. There were significant differences in the polyphenols content between bean cultivars and treatments processes. These results suggest that soaking and cooking favored the extraction of polyphenols, important for human health as kidney beans are an excellent source of phenolic compounds with antioxidant activity.