Bioaccessibility of carotenoids, tocochromanols, and iron from common bean (Phaseolus vulgaris L.) landraces

Common beans (Phaseolus vulgaris L.) are among the most important legumes for human nutrition. The aim of the present study was to characterize the composition and in vitro bioaccessibility of tocochromanols, carotenoids, and iron from 14 different landraces and 2 commercial common bean varieties. Phytic acid, dietary fiber, and total (poly)phenolic content were determined as factors that can modify the bioaccessibility of the studied compounds. Two carotenoids were identified, namely lutein (4.6-315 ng/g) and zeaxanthin (12.2-363 ng/g), while two tocochromanols were identified, namely γ-tocopherol (2.62-18.01 µg/g), and δ-tocopherol (0.143-1.44 µg/g). The iron content in the studied samples was in the range of 58.7-144.2 µg/g. The contents of carotenoids, tocochromanols, and iron differed significantly among the studied samples but were within the ranges reported for commercial beans. After simulated gastrointestinal digestion, the average bioaccessibility of carotenoids was 30 %, for tocochromanols 50 %, and 17 % for iron. High variability in the bioaccessible content yielded by the bean varieties was observed. Dietary fiber, phytic acid and total (poly)phenol contents were negatively correlated with the bioaccessibility of carotenoids, while iron bioaccessibility was negatively correlated with the total (poly)phenol content. The principal component analysis indicated that the bioaccessibility of lutein was the main variable involved in class separations. The composition of the food matrix plays an important role in the bioaccessibility of carotenoids, tocochromanols and iron from cooked beans.