Phytoremediation is an emerging technology where specially selected and engineered metal-accumulating plants are used for bioremediation. This study was undertaken to evaluate the potential of Amaranthus dubius for phytoremediation of chromium (Cr), mercury (Hg), arsenic (As), lead (Pb), copper (Cu) and nickel (Ni). Locally gathered soil and plants of A. dubius were investigated for the metals from a regularly cultivated area, a landfill site and a waste water treatment site. Metals were extracted from the samples using microwave-digestion and analyzed using Inductively Coupled Plasma–Mass Spectroscopy. The mode of phytoremediation, effect of the metals on the plants, ability of the plant to extract metals from soil (Bioconcentration Factor) and the ability of the plants to move the metals to the aerial parts of the plants (Translocation Factor) were evaluated. The survey of the three sites showed that soils were heavily contaminated with Cr, Hg, Cu and Ni. These levels were far above acceptable standards set for soils and above the standards set for the Recommended Dietary Allowance. Specimens of A. dubius from the three sites showed that they could tolerate Hg, sequester it from the soil, and translocate it to the shoots. Cr could only be removed from the soil and stored in the roots, with limited amounts translocated to the aerial parts. Pb, As, Ni, and Cu have some degree of transportability from the soil to the roots but not to aerial parts. The ability of A. dubius to be considered for phytoremediation has to be viewed with caution because translocation of the metals to the aerial parts of the plant is limited.

This study investigated the effect of processing on anti-nutritional factors of thirteen traditional leafy vegetables collected in Kwa Zulu-Natal, South Africa. The aim was to determine whether processing reduced anti-nutrient levels of leafy vegetables. The vegetables were boiled in a plant-to-distilled water ratio of 1:4 (w/v) at 97 °C for a time period of 5 and 15 min. The vegetables studied were: Amaranthus dubius, Amaranthus hybridus, Asystasia gangetica, Bidens pilosa, Ceratotheca triloba, Chenopodium album, Emex australis, Galinsoga parviflora, Guilleminea densa, Momordica balsamina, Oxygonum sinuatum, Physalis viscosa and Solanum nigrum. From this study, it was determined that non processed samples contained anti-nutrients such as tannins, phytic acid, alkaloids, oxalic acid, and cyanogenic glycoside. Both boiling parameters were effective in reducing the tannin, phytic acid, alkaloid, oxalic acid and cyanogenic glycoside contents of all 13 traditional leafy vegetables. The results of this study provide evidence that the local traditional leafy vegetables which the population is so reliant upon, are important contributors to micronutrient malnutrition in developing countries and can be minimized through common boiling methods for a minimum of 5 and maximum of 15 minutes.

Hibiscus sabdariffa is an under-utilized plant that has reported to have great potential in the food industry. The vibrant red pigment from the calyces indicate a source of anthocyanins. Anthocyanins would make ideal natural food colourants with additional nutritional benefits however stability is a hindering factor. Stability studies were the main focus of this study. Crude anthocyanins were extracted using four different solvent systems. The crude extracts were analysed under the following parameters; heat (50 and 80 °C), light (darkness and 20 W light) and pH (pH 1-9) stability. Degradation kinetic studies were done on thermally treated samples. Radical scavenging ability was thereafter calculated. Anthocyanidins were identified and quantified by HPLC coupled with a Diode Array Detector (DAD). Total phenolic content was determined with Folin – Ciocalteu’s method. Approximately 87% of pigments were retained when heated at 50 °C while heating at 80 °C resulted in 61% pigment retention. The pH stability of samples incubated for 7 days indicated that crude anthocyanins degraded slower at acidic pH. Light stability showed slower degradation in dark incubated samples resulting in 84% pigment retention after a 10 day period. H. sabdariffa shows potential for the application of a food in products such as jelly and yoghurt.