PHENOLIC ACIDS PROFILES OF BLACK BEANS

Authors: Luthria, Devanand - Dave; PASTOR-CORRALES, MARCIAL - VEGETABLE LABORTORY, PSI

Submitted to: Bean Improvement Cooperative Annual Report
Publication Type: Trade Journal
Publication Acceptance Date: 2/24/2005
Publication Date: 3/1/2005
Citation: Luthria, D.L., Pastor-Corrales, M.A. 2005. Phenolic acids profiles of black beans. Bean Improvement Cooperative Annual Report, 48:50-51.

Interpretive Summary: Dry beans are a staple food for many Latin American and African countries and are largely recognized as a beneficial source of proteins. There are several publications linking bean consumption to reduced risk of diabetes, obesity, cancer and cardiovascular diseases. The potential health benefits of beans have been attributed to the presence of micronutrients, such as phenolic compounds, that possess antioxidant properties. The research publications on beans have primarily been focused on isolation and identification of anthocyanins, flavonol glycosides and isoflavones and. This report describes isolation and identification of phenolic acids from three black bean cultivars. Ferulic acid, p-coumaric acid and sinapic acid were three main phenolic acids identified in all three cultivars, however, quantifiable amounts of caffeic acid were isolated from only in two cultivars (T-39 and Eclipse). This result can either be used by nutrient data laboratory for nutrient database and also enable researcher to develop new nutritional enriched bean cultivars.

Technical Abstract: A high performance liquid chromatography procedure with diode array detection (DAD) was used for analysis phenolic acids content from three cultivars of black bean (Phaseolus vulgaris L.) commonly consumed in United States of America. All samples were obtained from Dr. Pastor-Corrales of Vegetable Laboratory, Plant Sciences Institute, USDA (Beltsville, MD). Samples were grounded, saponified and free phenolic acids were extracted with ethyl acetate. The ethyl acetate extract was evaporated and residue was dissolved in methanol:water (75:25, % v/v) prior to HPLC analysis. Ferulic acid, p-coumaric acid and sinapic acid were identified in all three varieties. However, caffeic acid was identified in quantifiable amount only in two cultivars, namely, T-39 and Eclipse. Ferulic acid was the major phenolic acid in all three cultivars of black bean. Intermediate levels of p-coumaric acid and sinapic acid were identified in all three cultivars. The average total phenolic acid content for all three black bean cultivars was determined to be 0.38 mg/g. The total phenolic acid content among all samples varied between 0.24-0.48 mg/g of bean samples. Highest amount of total phenolic acid was extracted from T-39 cultivar. However, total phenolic acid content in Jaguar cultivar was 40%-50% lower as compared to the other two cultivars (T-39 and Eclipse).