Silicon biofortification of leafy vegetables and its bioaccessibility in the edible parts

BACKGROUND: Themineral silicon (Si) is an essential element for humans and a general component of the diet found mainly in plant-based foods. The aim of this study was to obtain Si biofortificated leafy vegetables (tatsoi, mizuna, purslane, basil, Swiss chard, and chicory) to use for the fresh-cut products (ready to use). For the production of biofortified plants, a floating system with 0, 50 and 100 mg/L of Si in nutrient solution,wasused. In addition, the assessmentofbioaccessibilityofbiofortified plants, by in vitro gastro-digestion process, was performed. RESULTS: The added silicon in nutrient solution did not influence yield and colour of vegetables but a species-related accumulation of Si (expressed as SiO2) was found: from 18 to 69 mg/kg fresh weight (FW) in tatsoi, from 19 to 106 mg/kg FW in mizuna, from 15 to 93 mg/kg FW in purslane, from 41 to 294 mg/kg FW in basil, from 17 to 76 mg/kg FW in Swiss chard,and from 23 to76 mg/kg FW in chicory. The Si became bioaccessible in all species considered in a range from 23% (basil) to 64% (chicory). CONCLUSION: The application of Si to the nutrient solution in the range of 50–100 mg/L allows biofortification of leafy vegetables. In addition, the biofortified vegetables showed, on average, more bioaccessible Si, with respect to unbiofortified vegetables.