Nutrient composition of selected newly bred and established mung bean varieties

- Nutrient content of newly bred mung bean varieties compared with established ones.
- Phytic acid and mineral concentrations show little variation.
- Newly bred varieties are agronomically improved but not nutritionally.
- Plant breeders should include nutritional quality in their breeding objectives.

Seven newly bred and three established varieties of mung bean were analysed for proximate composition, minerals, anti-nutrients and in vitro mineral accessibility. They contained 18-23 g protein, 4.0-5.6 g crude fibre and 2.5-4.1 g ash per 100 g dry sample. Iron, zinc, calcium, sodium and potassium ranged from 3.4 to 4.6, 1.2 to 2.3, 79 to 115, 8.1 to 13.5 and 362 to 415 mg/100 g dry weight, respectively. Phytic acid and polyphenols averaged 769 and 325 mg/100 g dry weight, respectively. Varieties differed significantly in terms of nutrient and anti-nutrient contents. Phytic acid and polyphenols were negatively correlated with in vitro mineral accessibility and nutrient digestibility. Protein and starch digestibility ranged from 53 to 67 g/100 g dry weight and 20 to 29 mg maltose released/g dry weight, respectively. Average molar ratios of phytic acid to iron and zinc were 16.8 and 52.7, respectively. Differences in in vitro iron and zinc accessibility could not be explained by phytic acid to calcium nor magnesium molar ratios. However, the phytic acid amount in mung beans suffices to bind all minerals into indigestible complexes. The newly bred varieties have better agronomic yields but no better nutritional potential than the established varieties tested.