Considerations in the preparation of laboratory samples for the analysis of ochratoxin A in wheat

Zirdum²,

Chan³

et al. 2018

Cereal Chem

Background and objectives:The variability in gluten in non-gluten-containing grains (NGCG) processed using two preparation schemes was evaluated with the aim of minimizing effects of sample heterogeneity on gluten determined by enzyme linked immunosorbent assay (ELISA). The relationship between gluten concentration as determined by ELISA and visually assessed contamination of NGCG with wheat, durum, barley, and rye was investigated. Findings: Low variability between duplicate aliquots taken from test portions (0-30.6% relative standard deviation [RSD]) demonstrated the ELISA itself was precise. In the first scheme, variability among test portions ranged from 1% to 143% RSD, with only half in the range of 1-50%. Using scheme 2, variability in gluten among test portions ranged from 1% to 85% RSD, with more than three quarters in the range of 1-50%. High lipid content hemp seed was a particular challenge to grind, and this was reflected in higher variability in gluten results between test portions (mean RSD = 61%). Conclusions: Subsampling ground samples using rotary sample division and the use of a 1-g test portion in scheme 2 decreased the variability of gluten results for most samples. At concentrations relevant to existing thresholds of gluten contamination (e.g. 20 mg/kg), there was no relationship between gluten concentration in NGCG and cereal contamination as determined by visual inspection. Significance and novelty: This study provides guidance on how to improve the analysis of gluten contamination in NGCG by ELISA and describes the absence of a relationship between ELISA-determined gluten and the visual assessment of contamination in NGCG.

Section: Variability Observed In Schemesupporting

confidence: 77%

Reducing variability in the measurement of gluten contamination in oats, oilseeds, and pulses by improving sample preparation

Zirdum²,

Chan³

et al. 2018

Cereal Chem

“…13 The 10 kg laboratory sample of whole grain was comminuted using a Retsch SR 300 rotor beater mill fitted with a 750 μm screen and coupled with a Retsch DR 100 vibratory feeder. After comminution, the entire mass of ground grain was homogenized and divided into 10 × 1 kg portions on a rotary sample divider (Materials Sampling Solutions, Southport, Australia).…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Occurrence of Ergot and Ergot Alkaloids in Western Canadian Wheat and Other Cereals

Drul²,

Roscoe³

et al. 2015

J. Agric. Food Chem.

A new method was developed to analyze 10 ergot alkaloids in cereal grains. Analytes included both "ine" and "inine" type ergot alkaloids. Validation of the method showed it performed with good accuracy and precision and that minor enhancement due to matrix effects was present during LC-MS/MS analysis, but was mitigated by use of an internal standard. The method was used to survey durum and wheat harvested in 2011, a year in which ergot infection was particularly widespread in western Canada. A strong linear relationship between the concentration of ergot alkaloids and the presence of ergot sclerotia was observed. In addition, shipments of cereals from 2010-2012 were also monitored for ergot alkaloids. Concentrations of total ergot alkaloids in shipments were lower than observed in harvest samples, and averaged from 0.065 mg/kg in barley to 1.14 mg/kg in rye. In shipments, the concentration of ergot alkaloids was significantly lower in wheat of higher grades.

“…Samples from shipments were taken by Canadian Grain Commission inspectors using standardized procedures for automatic sampling during loading of shipments. A 10 kg portion of all samples was ground, homogenized, and sub‐sampled according to the procedure described previously (Tittlemier et al., 2012). Samples were ground fine enough that ≥85% of mass passed through a US 50 sieve (nominal sieve openings of 300 µm).…”

Section: Methodsmentioning

confidence: 99%

Fate of glyphosate in wheat during milling and bread production

Bestvater²,

Carlson³

et al. 2020

Cereal Chem

Background and objectives Glyphosate is an active ingredient in widely used herbicides; its residues have been observed in grain and grain‐based foods. This work investigated the fate of glyphosate and its degradation product aminomethylphosphonic acid (AMPA) in milling fractions of wheat and during the bread making process. Samples of wheat were pearled to obtain successive fractions representing outer kernel layers. Straight grade flour and bread were prepared from the two samples with the highest glyphosate concentration (2.1 and 2.8 mg/kg). Findings All pearling and milling product fractions, dough, fermented dough, bread crust, and bread crumb were analyzed for glyphosate and AMPA using solvent extraction with derivatization and liquid chromatography–tandem mass spectrometry. Glyphosate was the only residue detected in samples. On average, the pearling experiment demonstrated that 50% of the total glyphosate mass resided in the outer 17% of the kernels. Similarly, 81% of the total glyphosate mass in the wheat was associated with the bran, shorts, and feeds milling fractions. No changes in glyphosate concentration were observed during the preparation of dough, fermented dough, and bread. Conclusions Milling provides the best opportunity for reducing exposure to glyphosate, as the baking process did not affect glyphosate residues. Concentrations in bread made from straight grade flour will be approximately 4× lower than that made from whole grain flour. Significance and novelty The use of Canada Western Red Spring from commercial wheat shipments provide realistic glyphosate residue concentrations and also reflect the predominance of this type of wheat used in Canada and elsewhere for bread. Therefore, the outcomes from this study are particularly relevant for estimating consumers’ dietary exposure.