19 research outputs found
Geostatistical analysis of the spatial distribution of mycotoxin concentration in bulk cereals
Deoxynivalenol (DON) and ochratoxin A (OTA) in agricultural commodities present
hazards to human and animal health. Bulk lots are routinely sampled for their
presence, but it is widely acknowledged that designing sampling plans is
particularly problematical because of the heterogeneous distribution of the
mycotoxins. Previous studies have not take samples from bulk. Sampling plans are
therefore designed on the assumption of random distributions. The objective of
this study was to analyse the spatial distribution of DON and OTA in bulk
commodities with geostatistics. This study was the first application of
geostatistical analysis to data on mycotoxins contamination of bulk commodities.
Data sets for DON and OTA in bulk storage were collected from the literature and
personal communications, of which only one contained data suitable for
geostatistical analysis. This data set represented a 26-tonne truck of wheat
with a total of 100 sampled points. The mean concentrations of DON and OTA were
1342 and 0.59 mu g kg(-1), respectively. The results showed that DON presented
spatial structure, whilst OTA was randomly distributed in space. This difference
between DON and OTA probably reflected the fact that DON is produced in the
field, whereas OTA is produced in storage. The presence of spatial structure for
DON implies that sampling plans need to consider the location of sample points
in addition to the number of points sampled in order to obtain reliable
estimates of quantities such as the mean contamination