Selenium concentration and speciation in biofortified flour and bread: Retention of selenium during grain biofortification, processing and production of Se-enriched food.

The retention and speciation of selenium in flour and bread was determined following experimental applications of selenium fertilisers to a high-yielding UK wheat crop. Flour and bread were produced using standard commercial practices. Total selenium was measured using inductively coupled plasma-mass spectrometry (ICP-MS) and the profile of selenium species in the flour and bread were determined using high performance liquid chromatography (HPLC) ICP-MS. The selenium concentration of flour ranged from 30ng/g in white flour and 35ng/g in wholemeal flour from untreated plots up to >1800ng/g in white and >2200ng/g in wholemeal flour processed from grain treated with selenium (as selenate) at the highest application rate of 100g/ha. The relationship between the amount of selenium applied to the crop and the amount of selenium in flour and bread was approximately linear, indicating minimal loss of Se during grain processing and bread production. On average, application of selenium at 10g/ha increased total selenium in white and wholemeal bread by 155 and 185ng/g, respectively, equivalent to 6.4 and 7.1µg selenium per average slice of white and wholemeal bread, respectively. Selenomethionine accounted for 65-87% of total extractable selenium species in Se-enriched flour and bread; selenocysteine, Se-methylselenocysteine selenite and selenate were also detected. Controlled agronomic biofortification of wheat crops for flour and bread production could provide an appropriate strategy to increase the intake of bioavailable selenium.

Utilization of biosolids during the phytoremediation of hydrocarbon-contaminated soil.

Addition of anaerobically digested sewage sludge (biosolids) to soil may improve conditions for phytoremediation of petroleum hydrocarbons (PHCs) through improved soil chemical, biological, and physical properties. A 32-wk greenhouse study investigated three rates of biosolids addition (0, 13.34, and 26.68 g oven-dry biosolids kg(-1) oven-dry soil) and the presence or absence of smooth brome (Bromus inermis Leyss. cv. Carlton) plants on the removal of diesel (3.5 g kg(-1) oven-dry soil) in an industrial, sandy loam soil. Diesel PHCs were divided into two fractions based on equivalent normal straight-chain boiling point ranges (F2: nC10-nC16; F3: nC16-nC34). The addition of biosolids did not increase the extent of PHC degradation but did result in significantly greater first-order decay constants compared to unamended controls. Overall, the presence of plants did not increase the rate or extent of PHC degradation, relative to that observed in unamended, non-vegetated soils. Vegetation was, however, an important factor within the biosolids-amended soils as was observed by a greater extent of PHC degradation. Some of this decrease was attributed to plant-induced removal of biosolids components that were contributing to the F3 fraction. Overall, the low-amendment rate (13.34 g oven-dry biosolids kg(-1) oven-dry soil) was considered to be the most effective treatment because it produced the greatest overall PHC degradation rate (0.226 wk(-1) for total PHCs) and resulted in the greatest recovery of biosolids-derived N by smooth brome (26.6%).