Effect of ash filtrate and rock salt on iron biofortified beans

Abstract

In Northern and Eastern Uganda, ground salt (rock salt) and ash obtained from burnt crop residue and dried plants is used to produce filtrate for cooking hard-to-cook foods like dried legumes e.g. beans and cereals e.g. maize. Iron biofortified Beans have been bred to increase iron levels in beans to alleviate iron deficiency. The aim of this study was to investigate the effect of rock salt and ash filtrate on iron bioavailability in iron biofortified beans. Determination of pH of the condiments was done using pH meter. Iron analysis of ash and rock salt were done using the atomic absorption spectrophotometry. The bioavailability was assessed following in vitro digestion of the cooked bean samples as per Millers et al, 1981.Analysis of the samples was done by the Atomic absorption spectrophotometry and the results read in mg/L and then expressed in mg/Kg. Iron bioavailability was expressed as percentage in each sample. The results showed that ash filtrate had the highest pH of 11.80, rock salt 10.90, table salt 8.90 and deionized water as 7.10. Addition of ash filtrate and rock salt while cooking the iron biofortified beans decreased cooking time and iron bioavailability with the highest decrease being in the samples cooked with ash filtrate, rock salt, table salt and deionized water respectively. From the results of the study, the reduction of iron bioavailability in the samples cooked with ash filtrate and rock salt could be an attribute of increasing alkalinity in the condiments which has an effect of precipitating iron (ii) ion and iron (iii) ions rendering them insoluble in the gut. This has a negative health impact as use of ash filtrate and rock salt reduces bioavailability of iron.