Uptake of various trace elements during germination of wheat, buckwheat and quinoa

The practice of sprouting is widely used to improve the nutritional value of grain seeds. Several nutritive factors such as vitamin concentrations and bioavailability of trace elements and minerals increase during germination. The objective of this work was to study the enrichment of various essential trace elements during germination of wheat (Triticum aestivum), buckwheat (Fagopyrum esculentum), and quinoa (Chenopodium quinoa) seeds in order to improve their nutritional role as a source of bioavailable trace elements. Seeds were sprouted either in distilled- or tap-water and in five different electrolyte solutions to investigate the concentration-dependent uptake. The time-dependence was investigated by analyzing aliquots of the sprouts after certain germination periods. Samples were analyzed after freeze drying for their Li, V, Cr, Fe, Mn, Co, Cu, Zn, Sr, Mo, As and Se concentrations with inductively-coupled plasma mass-spectrometry (ICP-MS). As a control for possible changes in the biochemical metabolism of the sprouts, the biosynthesis of vitamin C was also determined by using reversed-phase ion-pair HPLC. It was shown that quinoa was the most resistant to the applied electrolyte solutions and had the highest uptake rates for almost all elements, followed by buckwheat and wheat. Greatest increases were observed for Co, Sr, and Li. No significant changes in vitamin C biosynthesis were observed between sprouts grown in different electrolyte solutions. The time-dependent uptake for most elements was characterized by a significant absorption during soaking of the seeds, followed by a lag phase during the first day of germination and an increased uptake during the second and third day. Se and As showed distinctly different uptake behaviors.