Detect mold contamination.

Fungal contamination of foods and feeds results in considerable economic losses, because it causes direct damage to crops, and creates discoloration, off-odors, taints and flavors, reduced yields and loss of nutritive value. More importantly, fungal contamination is associated with mycotoxin production, which has toxic effects on ingestion in both humans and animals.

For these reasons, the development of fast and reliable detection techniques is very important in the production and processing of foods. The goal of this research project is to develop and validate rapid and convenient broad-specificity assays that could be used in detecting general fungal contamination in cereals.

Scientists have developed and validated a variety of different methods, including broad-spectrum immunoassays using antibodies raised against the soluble fraction of the mycelium from several individual fungi as well as from mixed cultures. Both monoclonal and polyclonal antibodies were produced and evaluated in assays. Researchers selected a monoclonal antibody and fully validated it for the assay of barley extracts. The assay correlated well with traditional methods.

Researchers also developed an immunoassay for the steroid ergosterol, which is an index of the contamination by fungi. Several antibodies were produced following immunization with a range of ergosterol-protein conjugates. Investigators obtained preliminary evidence that some of these antibodies could be used in an immunoassay.

On another front, investigators used near-infrared spectroscopy (NIR) to determine the fungal load in cereals. NIR is used to predict the ergosterol content. A predictive model showed that NIR could accurately predict the ergosterol content of contaminated barley.

Scientists also used an electronic nose to detect volatiles emanating from moldy grains. The researchers found a suitable combination of electronic sensors that could be used for predicting the ergosterol content of grains. DNA probes for the detection of specific fungi were developed and evaluated. To facilitate routine use, the probes were incorporated into a simple membrane-based detection system involving reverse hybridization. Six fungal assays were shown to work on contaminated barley samples simultaneously.

Further information. Marian Kane, Immunodiagnostics, National Diagnostics Center, National University of Ireland, Galway, Ireland; phone: [phone]; fax: [phone]; email: [e-mail].