Concentrations of minerals and phenolic compounds in three edible sprout species treated with iron-chelates during imbibition

Iron (Fe) is an essential micronutrient involved in fundamental biological processes in both humans and plants. Iron deficiency is common in humans, making iron supplementation of foods an important area of research. Edible sprouts are a rich source of minerals and phenolic compounds beneficial to human health; our objective was therefore to investigate the effects of iron supplementation in sprouts. We supplemented iron concentrations in three species of edible sprouts (alfalfa, broccoli, and radish) by soaking the seeds in a high-iron solution, and subsequently measured the concentration of minerals and of phenolic compounds. Seeds were soaked in either Fe(III)-EDTA or Fe(III)-citrate at concentrations of 2.5, 5.0, or 10 mM for 5–8 h, and then were maintained with distilled water in a commercial sprouter for 5 days. The soaking treatment significantly increased the iron concentration in 5-day-old alfalfa sprouts by up to 1.8 times the concentration observed in the controls. For broccoli and radish sprouts, an insignificant trend toward higher Fe concentrations was observed. The accumulated iron in treated alfalfa sprouts was negatively associated with concentrations of other minerals such as Ca, Mg, Mn, and Na. Treated alfalfa sprouts showed a significant increase of 8.0–36.4% in total phenolic concentrations compared to the controls, whereas broccoli and radish sprouts showed no significant change in phenolic concentrations. In summary, soaking seeds with iron chelates enhanced the iron concentration of sprouts, especially alfalfa sprouts, and had a positive or neutral impact on the concentration of phenolic compounds, suggesting that this treatment could be used to improve the nutritional quality of some types of edible sprouts.