Nutritional characteristics of common beans studied in the BIO-BELIEF project: macronutrient and iron content in 13 commercial and experimental bean lines

Common beans (Phaseolus vulgaris L.) are a nutrient-dense healthy food, due to their high protein, dietary fiber, and mineral content. In addition, they are rich in phytochemicals and compounds with antinutritional properties which can interfere with the absorption of some nutrients, potentially leading to nutritional deficiencies. Several anti-nutrients such as phytic acid, polyphenols, lectins and tannins can hinder iron (Fe) bioaccessibility and bioavailability. In many low-income regions, common beans represent a staple food and micronutrient deficiencies are widespread representing one of the main causes of malnutrition. Over the years, genetic improvement programs have been developed aimed at modifying the nutrient/anti-nutrient balance in beans and combining nutritional and agronomic traits to promote the growth under abiotic stresses. As part of the BIO-BELIEF project, a selection of 13 commercial and experimental bean lines were studied for their nutritional characteristics. Some of the lines are low phyitic acid (lpa) mutants. Samples were soaked and boiled in distilled water in the experimental kitchen of CREA-AN , and then analyzed for the content of water, proteins, lipids, and total dietary fiber according to the official methods of the AOAC, while Fe was detected by ICP-Plasma after liquid ashing. The results showed that the highest amount of protein was present in samples lpa1-1 (11.9 g/100 g f.w.) and 938 (11.2 g/100 g f.w.), with significant differences compared to the respective wild-type lines (BAT 93 and BAT 881). Total dietary fiber ranged between 5.9 g/100 g of HP5/1 to 9.0 g/100 g f.w. of PAN 146. The minimum value of Fe was detected in lpa1-1 (2.21 g/100 g f.w) and the maximum (3.19 g/100 g f.w) in lpa2. Considering a standard serving, corresponding to 150 g of the cooked beans, the lines BAT 93, lpa2, lpa3, BAT 881 and 938 cover around 45% (for men) and 25% (for women) of the Dietary Reference Value for Fe (LARN 2014). Furthermore, the data demonstrate that samples with the strong lpa trait (lpa1-1 and lpa1-2) are those with the lowest Fe content compared to the bean lines with moderate lpa trait (lpa2 and lpa3). This result suggests that the genetic profile may influence the content of this trace element and/or its loss during soaking and cooking.