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

The mineral 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(-1) of Si in nutrient solution, was used. In addition, the assessment of bioaccessibility of biofortified plants, by in vitro gastro-digestion process, was performed.

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(-1) fresh weight (FW) in tatsoi, from 19 to 106 mg kg(-1) FW in mizuna, from 15 to 93 mg kg(-1) FW in purslane, from 41 to 294 mg kg(-1) FW in basil, from 17 to 76 mg kg(-1) FW in Swiss chard, and from 23 to 76 mg kg(-1) FW in chicory. The Si became bioaccessible in all species considered in a range from 23% (basil) to 64% (chicory).

The application of Si to the nutrient solution in the range of 50-100 mg L(-1) allows biofortification of leafy vegetables. In addition, the biofortified vegetables showed, on average, more bioaccessible Si, with respect to unbiofortified vegetables.