Effect of cereal based traditional malting technology on nutritional quality of iron-rich bean flour

Abstract

Iron deficiency is a major public health challenge affecting the health of about 18 and 13.8% of children and women globally, respectively. About 43% children and 29% women in sub-Saharan Africa suffer from Iron Deficiency Anemia. In Uganda, recent demographic health statistics indicate that the prevalence of anaemia among children of 6-59 months stands at 53%; while that for women of child bearing age stands at 32%. Biofortified iron-rich bean varieties have been developed and adopted in Uganda to contribute to alleviation of iron deficiency challenges. The objective of this study was to investigate the effect of traditional malting technology on nutritional quality of biofortified iron-rich beans (Phaseoulus vulgaris L.). The study examined the effect of the traditional malting technology on: (i) the contents of anti-nutritional factors (phytates, oxalates, polyphenols, tannins, trypsin inhibitor activity); (ii) digestibility of protein and bioavailability of iron and zinc; and (iii) retention of proximate constituents and mineral micronutrient contents in bean varieties. We used three bean varieties, namely NAROBEAN 1, hereafter referred to as NB1, NAROBEAN 2 (NB2), and NAROBEAN 3 (NB3), all of which are widely produced and consumed in Acholi sub-region. Application of paired t-test revealed that the traditional malting technology reduced only the content of oxalates by 42.3-54.8 % and trypsin inhibitor activity by 6.2-34.6 %, from the three varieties. The content of total phenols was reduced by 22.3 % only in NB 1 (P< 0.05). The traditional malting technology improved protein digestibility for the three varieties by 38-43.6 % (P< 0.05). Bioavailability of iron improved from in NB1 by 26.7 % and NB2 by 11.5 %; while that of zinc improved for only NB2 by 51.5 % (P<0.05). The contents of micronutrients and proximate constituents were not adversely affected by the traditional malting technology, except for phosphorus in NB1 and magnesium in NB3. Overall, traditional malting technology is effective at reducing trypsin inhibitors and oxalates, and improving protein digestibility and iron bioavailability.