Deoxynivalenol, zearalenone, and Fusarium graminearum contamination of cereal straw; field distribution; and sampling of big bales.

Sampling of straw bales from wheat, barley, and oats was carried out after harvest showing large variations in deoxynivalenol (DON) and zearalenone (ZEN) levels. In the wheat field, DON was detected in all straw samples with an average DON concentration of 976 µg/kg and a median of 525 µg/kg, while in four bales, the concentrations were above 3000 µg/kg. For ZEN, the concentrations were more uniform with an average concentration of 11 µg/kg. The barley straw bales were all positive for DON with an average concentration of 449 µg/kg and three bales above 800 µg/kg. In oat straw, the average DON concentration was 6719 µg/kg with the lowest concentration at 2614 µg/kg and eight samples above 8000 µg/kg. ZEN contamination was detected in all bales with an average concentration of 53 µg/kg with the highest concentration at 219 µg/kg. Oat bales from another field showed an average concentration of 16,382 µg/kg. ZEN concentrations in the oat bales were on average 153 µg/kg with a maximum at 284 µg/kg. Levels of Fusarium graminearum DNA were higher in oat straw (max 6444 pg DNA/mg straw) compared to straw from wheat or barley. The significance of mycotoxin exposure from straw should not be neglected particularly in years when high levels of DON and ZEN are also detected in the feed grain. With a limited number of samples preferably using a sampling probe, it is possible to distinguish lots of straw that should not be used as bedding material for pigs.

Rapid and non-invasive analysis of deoxynivalenol in durum and common wheat by Fourier-Transform Near Infrared (FT-NIR) spectroscopy.

Fourier transform near-infrared spectroscopy (FT-NIR) was used for rapid and non-invasive analysis of deoxynivalenol (DON) in durum and common wheat. The relevance of using ground wheat samples with a homogeneous particle size distribution to minimize measurement variations and avoid DON segregation among particles of different sizes was established. Calibration models for durum wheat, common wheat and durum + common wheat samples, with particle size <500 microm, were obtained by using partial least squares (PLS) regression with an external validation technique. Values of root mean square error of prediction (RMSEP, 306-379 microg kg(-1)) were comparable and not too far from values of root mean square error of cross-validation (RMSECV, 470-555 microg kg(-1)). Coefficients of determination (r(2)) indicated an "approximate to good" level of prediction of the DON content by FT-NIR spectroscopy in the PLS calibration models (r(2) = 0.71-0.83), and a "good" discrimination between low and high DON contents in the PLS validation models (r(2) = 0.58-0.63). A "limited to good" practical utility of the models was ascertained by range error ratio (RER) values higher than 6. A qualitative model, based on 197 calibration samples, was developed to discriminate between blank and naturally contaminated wheat samples by setting a cut-off at 300 microg kg(-1) DON to separate the two classes. The model correctly classified 69% of the 65 validation samples with most misclassified samples (16 of 20) showing DON contamination levels quite close to the cut-off level. These findings suggest that FT-NIR analysis is suitable for the determination of DON in unprocessed wheat at levels far below the maximum permitted limits set by the European Commission.

Monitoring of a biogas process using electronic gas sensors and near-infrared spectroscopy (NIR).

The use of electronic gas sensors and near-infrared spectroscopy (NIR) to monitor the dynamics in a biogas process was evaluated using multivariate data analysis. The digester, a completely stirred 8 l tank reactor fed with a mixture of cellulose, albumin and minerals, was exposed to an overload of glucose after which monitoring of electronic gas sensor responses, NIR spectra as well as traditional chemical variables and analysis of microbial community structure were done. The responses from an array of electronic gas sensors consisting of MOS and MOSFET-sensors were correlated against volatile compounds in the headspace using partial least square (PLS) regressions. The root mean square error of prediction (RMSEP) was 0.15 g/l for acetate in the range of 0.14-1.72 g/l and the RMSEP for methane was 2.3% in the range of 27-73%. Selected wavelengths from the second derivative of the original NIR spectra (400-2500 nm) resulted in a PLS-model for predicting microbial biomass, measured as total phospholipid fatty acids, with a RMSEP of 9 nmol/ml in the range of 163-293 nmol/ml. The NIR model developed for acetate had a RMSEP of 0.20 g/l within the range of 0.14-1.72 g/l. The results clearly show that both NIR and an array of electronic gas sensors can provide simultaneous non-invasive in situ monitoring of important process variables in anaerobic digesters.

Fluorescence-linked immunosorbent assay (FLISA) for quantification of antibodies to food antigens.

Serum antibodies of the IgG type from rabbits immunized with food antigens (beta-lactoglobulin, ovalbumin and gliadin) have been quantified using a fluorescence-linked immunosorbent assay (FLISA), with the antigens adsorbed as round spots (about 8 mm in diameter) on glass or plastic microscope slides. The indirect immunofluorescence intensities were determined using a microscope fluorometer, and compared to enzyme-linked immunosorbent assay (ELISA) in microtiter plates and diffusion-in-gel-ELISA (DIG-ELISA) in plastic petri dishes. It was found that FLISA in general became more sensitive when the antigens had been adsorbed onto a plastic (Nunclon) than onto a glass surface. When the antigens were adsorbed to the plastic slides, the relative sensitivity order (maximum serum dilution) of the assays was in general the following, ELISA greater than FLISA greater than DIG-ELISA. The fluorescence-linked method appeared to require equal or less antigen and conjugated antiserum per sample. Due to the visual inspection of the surface, inhomogeneities of the antigen-coating could be readily discovered and evaluated by several measurements within the field of antigen-antibody reaction. It is proposed that spot FLISA may be an alternative to ELISA especially when the amount of antigen or antiserum is limited.