Sheryl A. Tittlemier

Sampling of cereals and cereal-based foods for the determination of ochratoxin A: an overview

The mycotoxin ochratoxin A (OTA) is known to be heterogeneously distributed both intrinsically (from one individual food item to the next) as well as distributionally (throughout a sample of individual food items) in cereals and cereal-based foods. Therefore, proper sampling and sample comminution are special challenges, but are prerequisites for obtaining sound analytical data. This paper outlines the issue of the sampling process for cereals and cereal-based foods, starting with the planning phase, followed by the sampling step itself and the formation of analytical samples. The sampling of whole grain and retail-level cereal-based foods will be discussed. Furthermore, possibilities to reduce sampling variance are presented.

Determination of melamine, ammeline, ammelide and cyanuric acid in infant formula purchased in Canada by liquid chromatography-tandem mass spectrometry.

A liquid chromatography-tandem mass spectrometry-based isotope dilution method was developed for the analysis of the triazine compounds melamine (MEL), ammeline (AMN), ammelide (AMD) and cyanuric acid (CYA) in infant formula samples purchased in Canada in 2008 for the purpose of a combined exposure and risk assessment. Infant formula samples were extracted with 1:1 acetonitrile–water, cleaned up on disposable ion-exchange solid-phase extraction cartridges, and analysed by ultra-high-performance liquid chromatography-tandem mass spectrometry. MEL and CYA were detected in almost all infant formula products: the highest concentrations observed were 0.32u2009mgu2009kg−1 MEL and 0.45u2009mgu2009kg−1 CYA. Samples that were relatively high in MEL in this survey tended to be low in CYA, and vice versa. Concentrations of AMN and AMD were very low in all samples. The total of MEL-related compounds (sum of all four analytes) in all samples was below the interim standard of 0.5u2009mgu2009kg−1 for infant formula products established by Health Canada.

DON occurrence in grains: A North American perspective

In agricultural commodities, the occurrence of deoxynivalenol (DON) has been reported all over the world, with levels varying among grain types and years of production. The grain supply chain, including growers, buyers, and end users, have effectively managed DON with strategies to control this issue systematically. The safety of consumers is ensured through use of these management strategies. This is observed in this review of the North American systems. This article describes the occurrence and management of DON in North America, which is accomplished by 1) a review of the toxicological effects of DON; 2) a review of publically available data and introduction of new information regarding the occurrence of DON in wheat, maize, and barley in North America, including variability due to growing regions, grain varieties, and year of production; 3) an overview of industry practices to reduce DON contamination from field through milling when necessary; 4) a review of how all in the value chain, including growe...

Fusarium Damage in Small Cereal Grains from Western Canada. 2. Occurrence of Fusarium Toxins and Their Source Organisms in Durum Wheat Harvested in 2010

Samples of Canadian western amber durum harvested in 2010 were obtained as part of the Canadian Grain Commission Harvest Sample Program, inspected, and graded according to Canadian guidelines. A subset of Fusarium -damaged samples were analyzed for Fusarium species as well as mycotoxins associated with these species, including deoxynivalenol and other trichothecenes, moniliformin, enniatins, and beauvericin. Overall, Fusarium avenaceum and F. graminearum were the top two most frequently recovered species. Phaeosphaeria nodorum (a.k.a. Septoria nodorum ), F. culmorum , F. poae , F. acuminatum , and F. sporotrichioides were observed in samples as well. All samples analyzed for mycotoxins contained quantifiable concentrations of enniatins, whereas beauvericin, deoxynivalenol, and moniliformin were measured in approximately 75% of the samples. Concentrations in Fusarium -damaged samples ranged from 0.011 to 34.2 mg/kg of enniatins plus beauvericin, up to 4.7 mg/kg of deoxynivalenol, and up to 6.36 mg/kg of moniliformin. Comparisons of enniatins, beauvericin, and moniliformin concentrations to the occurrence of various Fusarium species suggest the existence of an infection threshold above which these emerging mycotoxins are present at higher concentrations. The current grading factor of Fusarium -damaged kernels manages concentrations of these emerging mycotoxins in grain; lower provisional grades were assigned to samples that contained the highest concentrations of enniatins, beauvericin, and moniliformin.

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

A process used to prepare the test portion of ground wheat from the whole grain laboratory sample for ochratoxin A (OTA) analysis using dry comminution with homogenisation and sub-sampling via a rotary sample divider was developed and evaluated. With respect to OTA content, the developed process produced a homogeneous sample of ground wheat from 10 kg of whole grain. Relative standard deviations of the mean OTA concentration for five naturally contaminated wheat samples processed using the developed method ranged from 9% to 19% over a relevant concentration range of 1.7 to 7.6 mg/kg. Additional studies demonstrated that OTA was stable in ground wheat with moisture content between 12 to 13% for at least a year when stored at ambient temperatures. Further examination of the developed comminution and dividing procedure demonstrated that higher concentrations were measured in smaller sized particles, indicating that the accuracy and precision of OTA analyses could be affected by the particle size of ground wheat.

Analysis of polyfluorinated compounds in foods

Polyfluorinated compounds (PFCs) are a relatively new and diverse set of compounds analyzed as contaminants in food. Their unique physical-chemical properties dictate the methods used for their analysis. Current analyses of the more volatile PFCs involve gas chromatography–mass spectrometry; liquid chromatography–tandem mass spectrometry is generally used for the less volatile PFCs. Considerations in the analysis of PFCs in foods include contamination from the widespread presence of materials that contain various PFCs, endogenous interfering compounds, and matrix effects. Future opportunities for research on PFCs in food exist, particularly in the areas of biological molecule–PFC interactions and the effects of food processing on these interactions. Future research will be facilitated by the synthesis of a wider variety of analytical standards.

Single laboratory evaluation of a planar waveguide-based system for a simple simultaneous analysis of four mycotoxins in wheat.

The accuracy and precision of a commercially available system based on an indirect competitive immunoassay and planar waveguide technology was evaluated for the analysis of deoxynivalenol (DON), ochratoxin A (OTA), zearalenone (ZEAR), and T-2 toxin in wheat. The system generally performed well at the tested concentrations that were close to the regulatory limits of DON and OTA in wheat. The mean percent recovery of OTA from certified and in-house reference materials ranged from 90 to 111xa0%, with a relative standard deviation of 8–16xa0% (at 4.2, 4.9, and 7.0xa0μg/kg). Mean percent recoveries of DON ranged from 75 to 103xa0%, with a relative standard deviation of 14–20xa0% (at 610, 940, and 1300xa0μg/kg). As analyte concentrations approached the lower limits of the working range of 3xa0μg/kg OTA and 400xa0μg/kg DON, the mean percent recoveries and relative standard deviation increased for both DON and OTA. A lack of reference materials precluded a thorough evaluation of the method for the analysis of ZEAR and T-2. The particular strength of the technology was that multiple mycotoxins were analyzed simultaneously.

By-products of grain cleaning: an opportunity for rapid sampling and screening of wheat for mycotoxins

By-products of cereal grain cleaning were analysed for a number of mycotoxins. Deoxynivalenol (DON) was the most frequently detected in by-products from commercial-scale cleaning procedures (maximum 2.94 mg/kg), followed by zearalenone (ZEA; maximum 0.045 mg/kg) and ochratoxin A (OTA; maximum 0.019 mg/kg). These three mycotoxins were also the most frequently detected in four different fractions collected from wheat run through a dockage tester, a piece of equipment used in the Canadian inspection process to separate material other than grain from wheat. Concentrations of mycotoxins were highest in the ‘light dockage’ fraction that contained dust and roughage such as glumes, fragments of stem, or rachis. Mycotoxin concentrations in this fraction reached up to 32 mg/kg (DON), 0.532 mg/kg (ZEA), and 0.249 mg/kg (OTA). Concentrations of DON in light dockage were significantly correlated with concentrations in whole grain that was un-cleaned or had undergone basic cleaning, indicating that the light dockage fr...

Occurrence of ochratoxin A in Canadian wheat shipments, 2010–12

Randomly selected domestic and export shipments (n = 1907) of Canadian durum and other wheat that occurred between 1 January 2010 and 31 December 2012 were analysed for ochratoxin A (OTA). The majority of samples did not contain OTA above the LOQ of 1 μg kg–1. Only 37% of samples analysed contained quantifiable OTA; the median OTA of the positive results was 2.10 μg kg–1. Canada Western Amber Durum shipments contained OTA more frequently, and at slightly higher concentrations, than Canada Western Red Spring wheat. For both wheat classes the frequency of OTA occurrence and mean concentrations appeared to increase in the lower grades, but these increases were not statistically significant. A periodic trend of a late summer increase of mean monthly OTA concentrations in shipments appears tied to the cycle of producer deliveries of wheat to primary grain elevators.

Fusarium Diseases of Canadian Grain Crops: Impact and Disease Management Strategies

The genus Fusarium, first described in the early nineteenth century, is composed of a wide range of soil-borne saprophytic and pathogenic fungi. More than a few hundred different phylogenetic species of Fusarium have been identified to date. Plant species are the main target of Fusarium pathogenicity, although some species, including F. chlamydosporum, F. oxysporum and F. verticillioides, have been shown to infect immune-compromised humans. It is said that most plant species are susceptible to at least one disease caused by Fusarium fungi. Fusarium species can cause vascular wilt diseases, for which a broad range of host plants are susceptible, involving fungal colonization of the xylem via the roots and the growing mycelium eventually causes vessel obstruction, blocking transport of water to the aerial parts of the plant. In dicots, over 100 formae speciales of F. oxysporum have been identified as causative agents in vascular wilt, including F. oxysporum ff. spp. lycopersici, phaseoli and pisi, which infect tomato, beans and pea crops, respectively. Fusarium species also cause root rots and stem rots of various field crops worldwide, including peas and related pulse crops. In cereals and corn (maize) Fusarium crown rot (FCR) and Fusarium stalk (stem) rot, respectively, are caused by a different group of Fusarium pathogens from those responsible for diseases in dicots, and include F. graminearum, F. culmorum, F. avenaceum, F. verticillioides and F. pseudograminearum. In addition to root and stem rot diseases, Fusarium species also infect the inflorescence structures, causing Fusarium head blight (FHB; also known as scab) in cereals and Fusarium ear blight (sometimes referred to as FEB) in maize, and leads to damage and yield loss in developing kernels. There is an overlap of species responsible for Fusarium crown and stalk rots with those responsible for Fusarium head and ear blights. Many of these species produce harmful mycotoxins, including trichothecenes and fumonisins, which accumulate in the kernels of infected heads. In this chapter, we will start with an introduction to Fusarium species, their classification and genetics, provide a review of the Fusarium diseases of three groups of Canadian field crops (cereals, maize and pulses), followed by sections on disease management strategies, and Fusarium toxin quantification methods.