Submitted to: Journal of Food Composition and Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 26, 2005
Publication Date: October 1, 2005
Citation: Luthria, D.L., Pastor-Corrales, M.A. 2005. Phenolic acid content of fifteen dry edible beans (phaseolus vulgaris l.) varieties. Journal of Food Composition and Analysis. 19:205-211. Interpretive Summary: Dry beans are a staple food for the people of 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. This report describes isolation and identification of phenolic acids from fifteen varieties of beans commonly consumed in the United States. Ferulic acid, p-coumaric acid and sinapic acid were three main phenolic acids identified in all 15 varieties, however, quantifiable amounts of caffeic acid were isolated from only in two cultivars (T-39 and Eclipse). This result can either be used by the nutrient data laboratory for nutrient database and also enable researchers to develop new nutrition enriched and better flavored bean cultivars.
Technical Abstract: A high performance liquid chromatography-diode array detection (DAD) procedure separating and quantifying 16 phenolic acids was used for determination of phenolic acids content in dry beans (Phaseolus vulgaris L.). Dry beans from ten market classes and fifteen varieties that are commonly consumed in the United States were screened for phenolic acids content. All samples were ground and hydrolyzed with base in the presence of ascorbic acid and ethylenediaminetetraacetic acid and the free phenolic acids were extracted with ethyl acetate and analyzed by HPLC. Ferulic acid, p-coumaric acid, sinapic acid were detected and quantified in all varieties. However, caffeic acid was detected in measurable amount only in two Black bean (T-39 and Eclipse) varieties. The average phenolic acid content of dry bean sample was determined to be 31.2 mg/100 g. Total phenolic acid content among all samples varied between 19.1-48.3 mg/100 gram of bean samples. Ferulic acid was the most abundant phenolic acid present in all samples, whereas intermediate levels of p-coumaric acid and sinapic acid were extracted from all bean samples. Over 83% of the total phenolic acids were retained in bean samples during the cooking process and only 2% or less were detected in water extracts during overnight soaking.