Food Additives and Contaminants

Dry foods with high fat content are susceptible to lipid oxidation, which involves a quality deterioration of the product, since this process is responsible for the generation of off-flavours. Hexanal is considered to be a good shelf-life indicator of such oxidation products. In addition, due to its high volatility, hexanal can be easily determined by fast headspace analytical techniques. For this reason an electronic nose comprising ten metal oxide semiconductors (MOS) and a solid-phase microextraction (SPME) coupled with gas chromatography and flame ionization detector (GC-FID) method were compared in order to determine hexanal formed in hazelnuts during storage under different conditions (room temperature, 40 degrees C, ultraviolet light, with and without oxygen scavenger)...

Concentrations of fungal metabolites were measured in 32 wheat grain samples from north-eastern Poland in 2003. The samples originated from fields cultivated conventionally (but varying in chemical protection level) or cultivated organically. Concentrations of Fusarium toxins (HT-2, DON, 3-AcDON, NIV), trichodiene, microbial biomass indicators (fungal ergosterol and general adenosine 5'-triphosphate (ATP)) and seed vigour were assessed. A large variation between samples was observed, depending on their origin...

The performance characteristics of an analytical method based on high-performance liquid chromatography (HPLC) for the detection of the banned growth promoters, carbadox and olaquindox, in feedstuff were determined via a collaborative study. The relative standard deviation of repeatability (RSDr) ranged 1.1-5.5% for carbadox and 2.5-6.2% for olaquindox. The relative standard deviation of reproducibility (RSDR) ranged 6.4-10.7% for carbadox and 12.8-20.0% for olaquindox. In all cases, the HORRAT values were equal or below the critical value of 1...

An alternative, rapid, and reproducible method of analysis for perchlorate in selected food products (fruit and vegetable juice, milk, and bottled water) was developed and validated. Improvements over previous methods were achieved by the use of a rugged and inexpensive C18 column, a multi-mode OASIS HLB solid-phase extraction cartridge for sample clean-up, and acetic acid for pH adjustment and protein precipitation. The hydrophobicity of the perchlorate anion gives it good retention and separation characteristics on C18 chromatographic columns...

The sorption of 14 aroma compounds into PET and PVC was monitored during storage of a strawberry syrup for 1 year. Concentrations in the syrup and in the polymer were determined during storage and compared with previously published results obtained with glass bottles. Apparent partition coefficients between the polymer and the syrup (noted K app) were estimated from experimental kinetics without reaching equilibrium K app values and optimally identified from the kinetic data obtained between 30 and 90 days...

A method of screening sultanas for ochratoxin A (OTA) contamination, using mid-infrared spectroscopy/Golden Gate single-reflection ATR (attenuated total reflection), is described. The main spectral characteristics of sultanas from different sources were identified in a preliminary acquisition and spectral analysis study. Principal component analysis (PCA) showed that samples of various origins had different spectral characteristics, especially in water content and the fingerprint region. A lack of reproducibility was observed in the spectra acquired on different days...

The investigation of adverse health effects associated with fungal mycotoxins requires the measurement of human exposure. Most frequently, this exposure is estimated from contamination levels of raw foodstuffs, which are the primary source of toxin exposure, and data on food consumption patterns. However, variations in food preparation methods, food intake, contamination level, intestinal absorption, toxin distribution and excretion lead to individual variations in toxin exposure that are more readily measured with a biomarker...

A multi-analyte method for the liquid chromatography-tandem mass spectrometric determination of mycotoxins in crude grain extracts without clean-up has been applied to the analysis of spelt, rice and barley. Method performance characteristics were determined after spiking blank samples at multiple levels and were found to be comparable for all investigated matrices as regards linearity (linear calibration functions were obtained for all analyte/matrix combinations except for moniliformin), precision (coefficient of variations <6%) and sensitivity...

This review focuses on recent developments in immunochemical methods for detection of mycotoxins, with a particular emphasis on simultaneous multiple analyte determination. This includes high-throughput instrumental analysis for the laboratory environment (microtitre plate enzyme-linked immunoabsorbant assay (ELISA), different kinds of immunosensors, fluorescence polarization immunoassay, and capillary electrophoretic immunoassay), as well as rapid visual tests for on-site testing (lateral-flow, dipstick, flow-through and column tests)...

There has been interest in the development of techniques for the rapid early detection of mycotoxigenic moulds in the food production chain. The development of sensor arrays that respond to the presence of different volatiles produced by such moulds has been examined as a potential method for the development of such detection systems. Commercial devices based on such sensor arrays, so-called 'electronic noses', have been examined extensively for the potential application of determining the presence of mycotoxigenic moulds in food raw materials...

Aspergillus niger and A. tubingensis, species belonging to section Nigri, are commonly found in plant products and processed food, such as grapes, cereals, coffee, and derived products. These two species are very difficult to differentiate by classical morphological criteria and some isolates are known to produce ochratoxin A. The exact identification of these two species is very important to avoid the overestimation of toxicological contamination and related risks. A polymerase chain reaction (PCR)-based identification and detection assay was developed as a tool to identify A...

Single-stranded conformational polymorphism (SSCP) analysis for genetic diversity studies has been widely applied to detect indirectly sequence differences up to a single base in amplified DNA fragments of the same length, representing an alternative to gene sequencing. In this study SSCP analysis was used to detect sequence variations contained in an about 180-bp region of the calmodulin gene in order to identify Aspergillus section Nigri species. The method described shows that fluorescence-based SSCP analysis by capillary electrophoresis is cheaper and faster than direct sequencing, and suitable for computer-assisted analyses allowing discrimination between the Aspergillus species belonging to the Nigri section: A...

Black aspergilli, and particularly Aspergillus carbonarius, are responsible for ochratoxin A production in grapes. Correct identification of these species is essential for toxicological risk assessment in grape and wine. A low-complexity oligonucleotide microarray (OLISA, Apibio, F) based on DNA oligonucleotides probes, obtained from sequences of the calmodulin gene, was set up in order to detect A. carbonarius, A. japonicus/A. aculeatus and A. ibericus isolated from grape. The designed microarray distinguished all Aspergillus species and the detection limit for A...

Fusarium proliferatum is a major cause of maize ear rot and fumonisin contamination and also can cause wheat kernel black point disease. The primary objective of this study was to determine whether nine F. proliferatum strains from wheat from Nepal can cause black point and fumonisin contamination in wheat kernels. For comparison, the study included three Fusarium strains from US maize. In test 1, all the strains but one produced significant symptoms of kernel black point; two strains decreased kernel yield; and four strains contaminated kernels with fumonisins B(1), B(2) and B(3) as determined by liquid chromatography-mass spectroscopy...

The accuracy of a quantitative polymerase chain reaction assay in quantifying the DNA of trichothecene-producing F. culmorum and F. graminearum within harvested wheat grains and head tissue was evaluated in comparison with incidences of infected kernels and deoxynivalenol levels. In a first experiment, six durum and bread wheat varieties were grown in randomized plots for a 2-year period, and inoculated with Fusarium macroconidia at six growth stages between heading and dough ripening, to obtain a wide range of Fusarium head blight incidences...

Gibberella zeae (anamorph Fusarium graminearum) causes Fusarium head blight of wheat. The authors used amplified fragment length polymorphisms (AFLPs) to characterize the genetic structure of two G. zeae populations from commercial wheat fields. The working hypothesis was that sufficient genetic exchange occurs between local populations to prevent significant partitioning of allelic variation. We analysed 216 AFLP loci for 113 isolates collected during the 2002 harvest season. All strains had AFLP profiles typical of G...

Aflatoxins are a common contaminant of cereals that can cause cancer, liver disease, immune suppression, retarded growth and development, and death, depending on the level and duration of exposure. Maize is an introduced crop to Africa and there have been efforts over the last 20 years or so to replace traditional cereal crops, such as sorghum (Sorghum bicolor) and pearl millet (Pennisetum glaucum), with maize. We found that maize was significantly more heavily colonized by aflatoxin-producing Aspergillus spp...

Understanding the source of Aspergillus flavus is required to manage aflatoxin contamination of maize (Zea mays L.). Studies assessed A. flavus propagules, Fusarium spp., and total fungi associated with Mississippi Delta soils. Soils from 12 and 15 sites were collected in 2000 and 2001, respectively. The propagule density of A. flavus ranged from log(10) 2.0 to 4.3 colony-forming units (cfu) g(-1) soil, while total fusaria ranged from log(10) 3.0 to 5.4 cfu g(-1) soil. The highest populations of A. flavus were associated with soils containing higher organic matter, especially in sites under a no-tillage management...

Polyketides are a structurally diverse class of secondary metabolites produced by bacteria, fungi, plants and animals. The fungal genus Fusarium includes agronomically important plant pathogenic and mycotoxin-producing species and produces numerous polyketides. The study further characterized a polyketide synthase-encoding gene (PKS3 = PGL1) that was previously identified in F. graminearum and F. verticillioides. Disruption of the F. verticillioides PGL1 indicated that it is required for the production of the dark pigment in perithecial walls, as previously shown in F...

It is demonstrated that, in fungal cells grown in synthetic media, the Apyap1 gene is implicated in the modulation of aflatoxin biosynthesis following the perturbation of redox balance. This study suggests that an association between oxidative stress and aflatoxin biosynthesis also occurs in maize seeds. We used DeltaApyap1, a strain in which the gene Apyap1 was disrupted, to verify whether this oxidative stress-related transcription factor, by affecting cell redox balance, can have a role in the modulation of aflatoxin synthesis...