1. The importance of controlling microorganisms in cereals
- Cereals (rice, wheat, maize, oats...) are the staple food source for most of the world's population. However, during cultivation, harvest, storage, and processing, cereals are easily contaminated by microorganisms such as bacteria, molds, and yeasts.
- Microbiological contamination not only affects product quality but also poses serious risks to consumer health, such as food poisoning, allergies, or the accumulation of dangerous mycotoxins such as aflatoxin and ochratoxin A...
- Establishing microbiological contamination limits is therefore a mandatory requirement in cereal quality control at both national and international levels.
2. Common microbiological targets in cereal testing
When assessing the microbiological quality of cereals, regulators usually focus on the following parameters:
3. Microbiological limits under Vietnamese and international regulations
3.1. Vietnam (under QCVN 8-3:2012/BYT and TCVN 7597:2007)
3.2. Codex Alimentarius (FAO/WHO)
- Salmonella: must not be detected in 25 g of product.
- Bacillus cereus: < 10³ CFU/g (acceptable limit).
- Yeast and mold: limits vary by product type, usually < 10³ – 10⁴ CFU/g.
3.3. EU Regulation 2073/2005/EC
- Salmonella must be absent in 25 g.
- E. coli usually < 10 CFU/g.
- Bacillus cereus: below 10³ CFU/g.
4. How microbiological contamination affects health and quality
- Decline in sensory quality: off odors, color changes, clumping texture...
- Loss of nutritional value: bacteria and molds break down proteins and starches...
- Risk of food poisoning: from Salmonella, Bacillus cereus, and toxin-producing molds.
- Chronic toxicity: through mycotoxin accumulation in the liver, kidneys, and immune system, and it can cause cancer.
5. Microbiological testing measures across the cereal production chain
- Field control: apply clean farming practices and avoid untreated organic fertilizers.
- Harvest and dry with correct technique: reduce moisture below 13–14% to limit mold growth.
- Store properly: in dry, clean, well-ventilated warehouses with temperature and humidity control.
- Use treatment technologies: steam spraying, irradiation, ozone...
- Test cereals for microorganisms: apply rapid methods such as Compact Dry plates, standard colony counting, PCR detection of Salmonella, mycotoxin testing...
Determining and complying with microbiological contamination limits in cereals is not only a legal requirement but also a prerequisite for food safety and product quality. Cereal producers and processors therefore need to build an effective microbiological control system, from raw material to finished product, to meet domestic regulations and international standards while protecting consumer health.