Effect of Different Drying Methods on the Mineral Composition of Three Indigenous Leafy Vegetables

Abstract

Leafy vegetables are known to contain high amounts of nutrients and phytochemicals which support growth and development in humans after consumption. Due to their high moisture content at stage of maturity, the rate of perishability is high. The objective of this study was to determine the effect of three drying techniques on the nutritional quality of three indigenous leafy vegetables. The experimental design was a 3x3 factorial arranged in Completely Randomized Design (CRD). The factors were; leafy vegetables at three levels (Amaranthus cruentus, Celosia argentea and Laportea aestuans) and drying methods at three levels (Solar, Oven and Freeze drying). Our results showed that A. cruentus significantly (p < 0.05) had the highest phosphorus (0.79 %), potassium (2.22 %) and magnesium (1.15 %) and C. argentea recorded the least concentrations (0.40, 1.26 and 0.61 %) respectively. The concentration of calcium was in ascending order of A. cruentus < C. argentea < L. aestuans with 2.04 < 2.28 < 3.03 % respectively. Iron and zinc contents were higher in C. argentea than A. cruentus and L. aestuans. Moreover, calcium content in freeze dried vegetables with exception of C. argentea increased as compared to Solar and Oven drying. Also, the concentration of phosphorus was in ascending order of C. argentea < L. aestuans < A. cruentus with 0.44 < 0.60 < 1.04 % respectively for freeze drying. It can therefore be concluded that the three indigenous leafy vegetables are good sources of nutrients and these three drying techniques are for the preservation of their nutrients as well as preventing postharvest losses.