In a two-part blog series, we follow the cereal supply chain to explore the key risk areas for food contamination.
Part two: Â fromÂ food processing plant to the supermarket shelf.
In part one of this series, we traced the multiple risks of contamination present at various stages of the cereal supply chain, from farming through to transport to a food processing facility.
In this blog, we continue to follow the journey along a supply chain – from food production to supermarket.
Risks at food processing sites
Contamination can occur at multiple points in a food processing plant and for many reasons, but following good design, hygiene and cleaning practices can minimise any risk.
Where possible, a building used for food processing should be designed to minimise the risk of pest infestation and cross-contamination and promote good food hygiene practices. For example:
- inadequate covers for drains or windows in food preparation areas or poorly maintained facilities can increase the chance of rodent and insect infestation
- inadequate cleaning/washing facilities can increase the risk of staff transferring bacteria or viruses to the production line
- food products used in processing should be stored in pest-proof containers off the ground and away from walls
- areas around food processing factories should be kept clean to avoid attracting pests and there should be separate covered waste areas to avoid waste products contaminating production lines
Cleaning and sanitation
Food processing plants need to employ a robust cleaning system to avoid chemical, physical, animal or microbial contamination. Any reusable containers which come into contact with food need to be designed so they can be cleaned and disinfected adequately and equipment used in food processing should be cleaned regularly.
Production lines should be cleaned down in between the processing of different food products to avoid cross-contamination. Equipment used in the process should be durable and where possible, capable of being moved or disassembled to allow for cleaning and to inspect for pests. Regular monitoring should take place to ensure cleaning is adequate and good cleaning practices are maintained.
Food handler hygiene
Contamination with bacteria or viruses can occur when a food handler is suffering from an illness or disease which can be transmitted through food. Poor personal hygiene, such as failure to wash hands properly before starting a shift, after going to the toilet or after handling raw food, can also lead to contamination.
If a worker doesnâ€™t wear appropriate clothing, hair and other debris can fall in. Personal habits, such as coughing, spitting or smoking over unprotected food, also creates risk which can lead to foodborne illness in the end consumer.
Training staff to follow good hygiene practices and employing a hand washing monitoring system can reduce the risk of contamination. Having a health and safety policy with detailed procedures to follow in the event of illness can help reduce the risk of staff transmitting it to food.
Treatment of grain during processing
The exteriors of many grains retain natural flora as well as mould growth and any contamination from other sources such as soil or insects. Scouring and washing reduces the number of micro-organisms, as does milling and removing the outer layer. Heating will destroy many pathogens.
However, certain bacteria such as Clostridium botulinum produce heat-resistant spores which can lead to botulism poisoning, a rare foodborne illness, but one which is fatal in around 10% of cases.
GMPs to reduce contamination risk
By following Good Manufacturing Practices (GMPs), food processing factories can reduce risk and ensure food safety regulations are met. Practices they should follow include:
- training workers to ensure they understand food hygiene and adhere to procedure
- having in place a food allergen control plan to prevent cross-contamination
- maintain records of cleaning schedules and clearly define those procedures
- consider having an environmental pathogen control programme
- have clearly defined and robust cleaning procedures in place
- define control procedures, document them and review regularly
- set critical limits on temperature and other conditions to ensure harmful micro-organisms and their toxins are either eliminated or reduced to safe levels
Transport of packaged food
Once food has been packaged it has to be transported to the supermarket or a food service facility. It also might not go directly to those end users and may be stored in a warehouse for days or even weeks before being distributed.
Provided food has been handled properly during earlier stages the chances of contamination are reduced. However, it is still possible for food to become spoiled or come into contact with different microorganisms, either through inadequate hygiene or improper storage practices.
Many foods require strict temperature control to maintain safety. Imagine if a pallet of frozen peas is left in a loading dock in the sun for too long. The consignment could partially defrost, creating the right conditions for bacterial or mould growth.
Vehicles should be designed and maintained to ensure food is protected during transport and can be cleaned adequately. If the vehicles used to transport one type of foodstuff are not properly cleaned before transporting another, contamination can also occur.
Packaged food can also become damaged during transportation, such as glass jars breaking and contaminating neighbouring products. Non-food products can also contaminate food if transported together.
Once again, having in place procedures for the monitoring of the food and following HACCP principles â€” identifying hazards and key points for contamination, setting acceptable limits and assessing current procedures, introducing steps to improve procedures and regularly monitoring and reviewing their effectiveness â€” can help mitigate the risk.
Storage and distribution of packaged food
Even at this late stage in the food chain, there are still multiple points at which food can become contaminated and cause a foodborne illness. Some of the main risks for contamination are the same as earlier in the food chain and include:
- inadequate hygiene and food handling by workers leading to microbiological contamination or physical contamination with hair, smoke and spit, for example
- damage and introduction of foodborne disease by rodents â€” chewed packaging, food contaminated with faeces and urine
- insect infestationÂ e.g. flies and cockroaches
- poorly designed buildings leading to inadequate cleaning and storage conditions and increasing the risk of contamination by pests
- inadequate cleaning leading to physical or chemical contaminants entering the food chain or allowing residues from food that has been previously stored to contaminate new food
- incorrect food storage conditions – if products are left at room temperature rather than being refrigerated, or it is thawed and refrozen or reheated, it can create ideal conditions for bacterial or mould growth
- handling raw food alongside prepared food can also result in cross-contamination. Critical limits and temperatures set based on HACCP principles can reduce the risk
Contamination risks in supermarkets
Even at this late stage, there are still multiple ways in which food can become contaminated.
Once food has reached a supermarket it is presented to the consumer in many different ways.
Fresh fruit and veg can be on open display, fridges offer raw products and fresh food counters can offer a mix of raw, bagged, prepared and packaged products. Other products are tinned, bottled and boxed.
Poor personal hygiene can lead to the transfer of microbiological organisms or physical contaminants to food.
Working while suffering from vomiting or diarrhoea, smoking, spitting, sneezing and eating around food are all unacceptable. Inadequate hand washing after handling cash, raw food products, going to the toilet and after using cleaning products can lead to contamination.
Rats and mice can gnaw packaging, not only physically damaging it, but also contaminating it with urine and faeces.
The can carry multiple diseases which are dangerous to humans. They are attracted by accessible food and water, for example, spills in loading bays or waste storage areas.
Flies carry numerous disease-causing microorganisms, including E. coli and Salmonella.
They feed on rotting food and faecal matter and then transfer it to clean areas and food they are feeding on.
Supermarkets are large buildings and poor design and maintenance can increase the risk of pest infestation.
Pests can enter through pipes, drains, small cracks, vents screens and holes in the roof.
Food areas and food preparation areas also need to have appropriate temperature, ventilation, lighting, adequate handwashing facilities, loading/unloading areas, storage, processing and packing areas.
The risk of food fraud is low in major supermarkets but occasionally does occur.
Food fraud can lead to products being adulterated or contaminated, causing serious risk to humans.
For example, in Australia a consignment of peanuts was found to have been relabelled pinenuts, creating a serious risk for allergy sufferers. Supermarkets can reduce the risk of food fraud by demanding traceability from suppliers.
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