Analysis of micronutrients and heavy metals of indigenous reed salts and soils from selected areas in Western Kenya

Abstract

Most communities in Western Kenya use plant indigenous salts for cooking, medicinal and numerous uses. Typha latifolia and Cyperus rotundus reeds are widely used in Busia and Lugari regions of Western Kenya to prepare indigenous salts. The suitability of these salts and validation of micronutrients and heavy metals is unknown. The objective of this study was to assess the suitability of the indigenous reed salt used in selected parts of Western Kenya. Micronutrients and heavy metal concentrations in soil habitats, C. rotundus and T. latifolia and reed salts were determined; In addition, the effect of the various methods of processing, storage conditions and the stability of iron and iodine nutrients has been investigated. Iodometric titration (Iodine), 1, 10-phenanthroline method (Iron II), flame photometric method (Na and K) and Atomic absorption spectrophotometric method (Pb, Cd, Fe, Cr) were used for analysis. Results showed that 85% of Lugari and Busia inhabitants in Western Kenya use C. rotundus and T. latifolia reed salts. Heavy metal in the soil was of the order Fe> Cr >Pb > Cd for the dry season and Cr > Fe > Cd > Pb for the wet season both in top and sub-surface soils with higher levels in the dry season. Salt iodine was of the order Kensalt >Top-chef salt > Herbal sea salt > Sea salt > C. rotundus salt > T. latifolia and Herbal sea salt >C. rotundus salt = T. latifolia salt > Sea salt > Kensalt = Top-chef salt for Fe2+. C. rotundus and T. latifolia reed salts had higher iodine (1.1 mg/kg) than the WHO limit of 0.015 - 1.1 mg/kg , while the concentration of Fe2+ (0.9 mg/kg and 1.0 mg/kg) was below the recommended limit of 8 - 45 mg/kg. The Na: K ratio of T. latifolia salt (3.2:1) was within the recommended limit of 2.5:1 - 4:1 while that of C. rotundus salt (0.9:1) is lower. Fe, Pb and Cd levels in both C. rotundus reed and T. latifolia reed salts exceeded the WHO/FAO permissible. Effectively all iodine and Fe2+ present in the reed salts was lost within six months of storage under normal conditions of temperature and RH with more losses at elevated temperature and relative humidity. T. latifolia salt prepared using complete evaporation method and stored in LDPE container for a period not more than three months is suitable for use as table salt. C. rotundus prepared by complete evaporation method is ideal for use as a low-sodium salt.