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Hart D.J.,UK Institute of Food Research | Fairweather-Tait S.J.,University of East Anglia | Broadley M.R.,University of Nottingham | Dickinson S.J.,Premier Foods | And 11 more authors.
Food Chemistry | Year: 2011

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 30 ng/g in white flour and 35 ng/g in wholemeal flour from untreated plots up to >1800 ng/g in white and >2200 ng/g in wholemeal flour processed from grain treated with selenium (as selenate) at the highest application rate of 100 g/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 10 g/ha increased total selenium in white and wholemeal bread by 155 and 185 ng/g, respectively, equivalent to 6.4 and 7.1 μg 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. © 2010 Elsevier Ltd. All rights reserved.

Chesterton A.K.S.,New Museums Site | Meza B.E.,New Museums Site | Meza B.E.,CONICET | Moggridge G.D.,New Museums Site | And 2 more authors.
Journal of Food Engineering | Year: 2011

Studies of cake batter rheology have focused on viscous behaviour. We demonstrate that elastic effects dominate at the shear rates used in commercial mixers. The development of batter structure was investigated for two flour types using two bench-scale planetary mixers with known shear rate profiles (Kenwood-KM250, maximum 100 s -1; Hobart-N50, 500 s -1). These wet foams (air volume fraction 0.39-0.45) showed shear-thinning behaviour at low shear rates (0.1-10 s -1), with apparent viscosity dependent on air volume fraction. Simple shear thinning behaviour ceased, for foams, above 10-20 s -1: for slurries (air volume fraction, 0.11-0.15) the limit approached 100 s -1. Elastic effects, predominantly arising from the bubble phase, therefore dominate cake batter behaviour at the shear rates experienced in commercial mixers. Filament thinning extensional rheometry confirmed the VE behaviour of batters. These results indicate that visco-elastic analyses are likely to be the most appropriate probe of microstructure in cake batters. © 2011 Elsevier Ltd. All rights reserved.

Chesterton A.K.S.,New Museums Site | De Abreu D.A.P.,University of Santiago de Compostela | Moggridge G.D.,New Museums Site | Sadd P.A.,Premier Foods | Wilson D.I.,New Museums Site
Food and Bioproducts Processing | Year: 2013

The incorporation of air into a high ratio cake batter by planetary mixing was studied using two bench mixers, a Kenwood KM250 and a Hobart-N50. Power draw (expressed as specific mechanical power input) and air volume fraction, φ, were monitored over time for batters prepared in each mixer for heat-treated and un-treated cake flours. The two flour types gave very similar results, indicating that the benefit of heat treatment for cake manufacture is manifested during the baking step. Both mixers gave a rapid initial increase in φ up to ∼0.50 followed by a gradual decay. Bubble size distributions of batters prepared in the Hobart showed the initial aeration stage to be accompanied by the formation of a large number of small bubbles, with diameters around 5 μm: the average bubble size increased and number of bubbles decreased with extended mixing. Batters prepared without emulsifier exhibited a steady increase in φ to a plateau at ∼0.2 and contained larger bubbles which did not change in average size significantly over time. All batters exhibited power-law shear-thinning behaviour with power law indices and consistency strongly dependent on φ. At low shear rates, the apparent viscosity showed the non-linear dependency on φ expected for dense suspensions. At higher shear rates, elastic forces generated by the bubble phase became significant. The non-Newtonian nature of the liquid phase and the elasticity generated by the bubbles meant that shear-thinning and bubble break-up could not be predicted by analyses based on the capillary number. The results support a qualitative model of bubble formation and break-up caused by extensional deformation generated by shearing these bubbly liquids: the bubbles cream out slowly owing to the high viscosity of the continuous phase at rest. © 2012 The Institution of Chemical Engineers.

Chesterton A.K.S.,New Museums Site | Wilson D.I.,New Museums Site | Sadd P.A.,Premier Foods | Moggridge G.D.,New Museums Site
Journal of Food Engineering | Year: 2015

A lab-scale method for replicating the time-temperature history experienced by cake flours undergoing heat treatment was developed based on a packed bed configuration. The performance of heat-treated flours was compared with untreated and commercially heat-treated flour by test baking a high ratio cake formulation. Both cake volume and AACC shape measures were optimal after 15 min treatment at 130 °C, though their values varied between harvests. Separate oscillatory rheometry tests of cake batter at 80-100 °C exhibited similar behaviour to the baking tests. The gel strength parameter in the weak gel model, measured at 100 °C, was shown to correlate with flour quality and was identified as a possible alternative to test baking as a means of assessing flour quality after heat treatment. © 2014 Published by Elsevier Ltd.

Chesterton A.K.S.,New Museums Site | Moggridge G.D.,New Museums Site | Sadd P.A.,Premier Foods | Wilson D.I.,New Museums Site
Journal of Food Engineering | Year: 2011

The shear rate experienced by a fluid near the wall of a planetary mixer when agitated by a wire whisk tool has been estimated using a simple geometrical analysis. The bowl and whisk geometries were measured for a Kenwood KM250 and a Hobart N50 mixer which are in widespread use in domestic and laboratory installations. The shear rate is shown to be a maximum at the bowl wall. This value is relatively uniform over a large fraction of the wall height, except for a small volume near the base and the region above the maximum width of the mixer. The shear rate profile is sensitive to the vertical positioning of the agitator within the bowl. For standard manufacturer speed settings, the range of maximum shear rates was estimated to be 100-500 s-1 in the Hobart and 20-100 s-1 in the Kenwood. © 2011 Elsevier Ltd. All rights reserved.

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