Severe drought conditions have not only resulted in lower crop yields, but the stress has made the resulting grain more prone to the development of mycotoxins from the growth of molds and fungi. Mycotoxins can present a very real health risk and government regulations limit their concentration in feedstuffs. Fungal and mold growth is opportunistic based upon the local or micro environment.
For example, warm days and cool nights may cause moisture to be released during the day, but condense during the cooler nights. In these conditions, the moisture content in grain stored in a metal bin may be great enough at the edges to support mold growth, even if the total moisture content would appear to be low enough to prevent storage issues.
Grains should be sampled for mycotoxins if:
- To assure compliance with legislation
- If requested by the seller
- If there are indication that presence of mycotoxin can be expected
Because mycotoxin concentrations are often not consistent across stored grain, poor or inadequate sampling techniques may result in either a false positive or negative result. Ideally grain samples should be taken at multiple times or sites, as grains are unloaded or probed, respectively.
USDA-GIPSA provides sampling recommendation for grain on their website in their Grain Inspection Handbook for both stream samples and probe samples (Grain Inspection Handbook – Book I Grain Sampling ). Penn State University recommends 12 to 20 “stream” samples from entire delivery or 12 to 20 deep probe samples from a bin, including edges of the storage. Samples should be mixed and a minimum of 500 gram final sample submitted for testing. Sample should be kept in a “breathable” paper or cotton sample bag to prevent potential mold growth during storage prior to testing.
For those selling grain, particularly for international shipping, it is important to meet regulatory requirements for proper sampling. EU regulations require sampling numbers in relationship to lot size.
Table 1. Subdivision of lots into sublots depending on product and lot weight for cereal and cereal products according to EU regulations (for food purposes)
|Lot weight (tonnes)||Weight or number of sublots||Number of incremental samples**||Aggregate sample weight (kg)|
|> 300 and < 1,500||3 sublots||100||10|
|>50 and < 300||100 tonnes||100||10|
* Depending on the lot weight — see Table 2.
Table 2. Number of incremental samples to be taken, depending on the weight of the lot of cereal and cereal products according to EU regulations (for food purposes)
|Lot weight (tonnes)||Number of incremental samples**||Aggregate sample weight (kg)|
|>0.05 and < 0.5||5||1|
|>0.5 and < 1||10||1|
|>1 and < 3||20||2|
|>3 and <10||40||4|
|>10 and < 20||60||6|
|>20 and <50||100||10|
** Incremental sample size is 100g
Regardless of sampling routine it is important for samplers to do their best to take samples that represents the entire load. Samplers should also consider testing cereal grains that have been in long term storage, even if initial samples appeared to be acceptable.
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