Grain, Milling storage & Silos

Most stored grain is destined to end up as either human or animal food. Food safety and quality are driving factors in the long-term storage of grain. In the food safety area, bacterial pathogens and mycotoxins must be considered. They are often used in specifications set by domestic and international buyers of Australian grain. Quality issues include spoilage due to mould growth, insect and mite infestation, and general hygiene issues such as protection from rodents and birds.

The bacterial species that occur commonly on grain are generally non-pathogenic, though contamination with bacterial pathogens such as Salmonella, Escherichia coli and Bacillus cereus can occur. Salmonella and E. coli are enteric bacteria, and their presence on grain is usually an indication that it birds or rodents have contaminated it. This may occur during harvesting, but more often is a result of poor hygiene in road or rail trucks during transportation, or poor pest control during storage.

The presence of mycotoxins in grain was traditionally regarded as an indicator of poor storage conditions. The corollary to this was that mouldy grain contained mycotoxins. Neither statement is necessarily true. Mycotoxins may be produced as a result of poor storage, but they may already be present in grain coming into storage. Conversely, not all moulds that grow in stored commodities produce mycotoxins. Some of the fungi associated with grain in the field (often referred to as ‘field fungi’) can form mycotoxins, either immediately before, or just after harvest. Alternaria, Fusarium, Aspergillus and Penicillium can all act as preor postharvest pathogens of grain, and may form mycotoxins. Alternaria and Fusarium do not compete strongly at reduced water activities (aw) so are unlikely to form mycotoxins once the grain is dry, or during storage. Conversely, Aspergillus and Penicillium are more often considered as ‘storage fungi’. They are known to form mycotoxins in stored grains, and are usually not regarded as fungi that can produce mycotoxins before harvest.

GRAIN AND MILLING

All cereal grains are exposed in the field to a wide variety of organisms originating from sources such as dust, water, diseased plants, soil, fecal matter of animals and birds, etc. The external surfaces of grains at harvest contain hundreds of microbial species.  Traditional means of decontamination use chemical additives that not only introduce the risk of product taint and color changes to the final product as well.

Maximal production output of the highest quality product is paramount to a mill. The busy milling environment requires effective microbial control which is essential to the quality of the milled product. Without an effective decontamination process in place, grain mills risk producing a lower grade product sold at a lower price.

EX-Water features for the Miller

  • Effective decontamination of raw grain at the conditioning stage
  • No product taint or residue carry-over.
  • Substantial shelf-life extension of final milled products
  • Effective control of fungal spores and other spoilage microbes
  • In process biofilm removal and control


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