Using grain dust to reduce mycotoxin screening time

Many methods for the analysis of mycotoxins in various agricultural commodities, including grain, are marketed as appropriate for ‘rapid’ screening. However, this often refers to the detection portion of the analytical method and ignores the time required for sampling and sample preparation, which if performed properly, can add a significant amount of time to the entire testing procedure.

By-product materials as matrices for bulk

In a quest to find ways to reduce the whole mycotoxins screening time, a group of Canadian researchers aimed to first measure mycotoxins in the by-products of commercial-scale cereal grain cleaning operations often performed at grain elevators (wheat grain dust). Hence they wanted to evaluate the feasibility of using such materials as matrices for the rapid screening of bulk whole grain wheat using common equipment routinely used in North American grain elevators.

DON was the most found in all samples

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. DON was observed at the highest frequency in 31 of 31 light dockage, 31 of 32 large dockage, 32 of 32 small dockage, and 6 of 9 cleaned grain samples. As mentioned previously, not all of the collected fractions were available for mycotoxin analysis from all samples in the second set, therefore there was slightly less data generated for ZEA and OTA. ZEA was quantified in light dockage (18/29 samples), large dockage (9/30), and small dockage (8/32) whereas OTA was only present at levels greater than the LOQ (Limits of Quantitation) in light dockage (20/29) and large dockage (3/30).

Possibility of using light dockage for matrix

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 fraction could be used as a readily available matrix for the rapid screening of DON in wheat. This would eliminate the time required for additional sampling and preparation of whole grain, and move towards a truly rapid method for the screening of DON in wheat.

Source: Wageningen Academic Publishers