Characterization of selenium-enriched wheat by agronomic biofortification.

Agronomic biofortification of staple crops is an effective way to enhance their contents in essential nutrients up the food chain, with a view to correcting for their deficiencies in animal or human status. Selenium (Se) is one such case, for its uneven distribution in the continental crust and, therefore, in agricultural lands easily translates into substantial variation in nutritional intakes. Cereals are far from being the main sources of Se on a content basis, but they are likely the major contributors to intake on a dietary basis. To assess their potential to assimilate and biotransform Se, bread and durum wheat were enriched with Se through foliar and soil addition at an equivalent field rate of 100 g of Se per hectare (ha), using sodium selenate and sodium selenite as Se-supplementation matrices, in actual field conditions throughout. Biotransformation of inorganic Se was evaluated by using HPLC-ICP-MS after enzymatic hydrolysis for Se-species extraction in the resulting mature wheat grains. Selenomethionine and Se(VI) were identified and quantified: the former was the predominant species, representing 70-100 % of the total Se in samples; the maximum amount of inorganic Se was below 5 %. These results were similar for both supplementation methods and for both wheat varieties. Judging from the present results, one can conclude that agronomic biofortification of wheat may improve the nutritional quality of wheat grains with significant amounts of selenomethionine, which is an attractive option for increasing the Se status in human diets through Se-enriched, wheat-based foodstuff.

Using single-particle ICP-MS for unravelling the effect of type of food on the physicochemical properties and gastrointestinal stability of ZnONPs released from packaging materials.

This article discusses the application of Single-Particle Inductively Coupled Plasma Mass Spectrometry (SP-ICP-MS) to study the effect of different types of food (orange juice and chicken breast) on the fate of zinc oxide nanoparticles (ZnONPs) migrated from two widely employed food packaging materials (polyethylene terephthalate (PET) and low density polyethylene (LDPE)). The gastrointestinal stability of ZnONPs was also evaluated. The idea behind this study is to track for first time the transformations underwent of nanoparticles in the different steps of their route from packaging to the consumer. The presence of high amount of dissolved zinc in the samples notably influenced size detection limit and the accuracy of SP-ICP-MS measurements. The diameter limits of detection (LODd) were 26 nm, 95 nm, 108 nm and 129 nm for aqueous solution, chicken breast extract and for oral and intestinal extracts, respectively. ZnONPs characterization in juice was not possible with SP-ICP-MS due to nanoparticles size was below LODd. Besides difficulties, SP-ICP-MS after extraction with Tris-HCl allowed us to determine that a 72% of the ZnONPs that migrated to chicken breast were smaller than 95 nm. Complementary to SP-ICP-MS, transmission electron microscopy (TEM) enabled to detect small nanoparticles (<3 nm). The combination of TEM and SP-ICP-MS measurements indicated that nanoparticles in chicken reach the intestine wall as small particles (<10 nm), as aggregates (>200 nm) and as ionic zinc whereas in case of juice only small nanoparticles (<3 nm) and ionic zinc were detected in the intestinal step.