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Testing the supply chain

15 July 2015

With increasing pressure on the food industry to ensure safe, quality foods, how often should the supply chain be sample testing?

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There are over 500,000 reported incidents of food poisoning from known pathogens in the UK annually and up to ten deaths from a recognised food allergy. Food fraud currently costs businesses over £11 billion, with over 1500 food contamination incidents reported every year.

Foodborne illnesses are a huge burden on global healthcare systems. “In the US alone, approximately one in six people (48 million people annually) become sick, 128,000 are hospitalised and 3000 die every year from diseases that can be traced to bacteria, viruses and other pathogens in food,” says Handy Yowanto, Senior Global Product Manager at SCIEX. And while monitoring food samples for known compounds can be relatively straightforward, sampling for pathogens including bacteria and viruses can be more challenging.

Complex supply chains
“While the simple answer to when and how often food sample testing should take place is at every stage in the supply chain, in reality however the answer is much more complex,” says Natalie Harvey, Global Marketing Manager Food Services at Intertek “The nature of the supply chain is that there are different requirements between retailers and the size of the organisation can have an effect too. For smaller businesses, for example, the supply chain tends to be relatively short, so regular testing will take place at the supplier, producer and retailer level. Larger organisations, on the other hand, tend to have much more vastly complex supply chains in order to reduce costs, extending back to suppliers and producers around the globe and resulting in distribution to international markets.”

In the case of larger organisations, they tend to rely on due diligence and trust, as the supply chain cannot be as tightly controlled. “Large organisations often have their own supplier management programmes in place to monitor and control each of their suppliers,” explains Harvey. “Here, frequent and random testing will take place, along with regular audits, in order to ensure the safety of ingredients and the end product.”

One size doesn’t fit all
When it comes to testing, the question of where and how often is largely dependent on who is ordering the testing, and why, according to Catherine Cockcroft, Head of Microbiological Services at Exova. “There may be many reasons why a food business wishes to conduct a laboratory analysis of foods or food ingredients,” she explains. “A manufacturer may wish to verify and/or validate HACCP (Hazard Analysis & Critical Control Point), determine product shelf life, monitor high risk raw materials or investigate a known microbiological issue, for example. On the other hand, a retailer or food service customer may wish to conduct their own due diligence programme of testing across their supply base.”

In Exova’s experience, the majority of microbiological testing that is conducted on foods is for the purpose of verification of HACCP by the food manufacturer. “With the introduction of risk-based, preventative food safety management systems, the industry has broadly moved away from positive release systems, meaning that manufacturers no longer await satisfactory laboratory results before releasing foodstuffs to market,” says Cockcroft. “This is particularly important given the rise in popularity of short shelf life, perishable foods where laboratory results may not be available until after the use-by date has passed.”

Instead, most food manufacturers follow a programme of finished product testing, with products typically analysed on Day of Production plus one (DOP+1). “This has the benefit of the results being available at the earliest possible opportunity following the production of the foodstuff,” Cockcroft continues. “Some microbiological tests may take up to seven days for a final confirmed result. The range of products sampled and the frequency at which they are tested may be in accordance with specific customer requirements, or following a risk assessment generated by the site.”

If HACCP has been verified, and if Critical Control Points within the manufacturing process are properly managed, then safe food should always be produced – in theory. This principle has served to significantly reduce the amount of laboratory testing conducted on finished products.

Using an approach of preventative food safety management coupled with verification makes good technical sense, especially because a laboratory analysis of a foodstuff can only ever reveal what microorganisms were in that small portion tested. “Due to the non-homogenous distribution of microorganisms in foods, it is not possible to extrapolate microbiological testing date with statistical significance to the whole batch, unless large numbers of samples are analysed,” says Cockcroft. “For example, if a batch of food is contaminated with Salmonella at a one per cent concentration, then 300 samples must be tested to have a 95% chance of detecting Salmonella – in the assumption of an even Poisson distribution. Testing at these numbers becomes a financial non-starter for food producers.”

Cockcroft does warn however that this isn’t true for all tests. “While testing at DOP+1 provides useful information regarding the hygienic manufacture of food products, it should be noted that manufacturers need to be aware that some organisms of significance may be present at low numbers at the start of life – below the limit of detection of a laboratory test – but may increase in number over life, leading to a potential food safety issue,” she says. “This is particularly true for Bacillus species, which are generally associated with starchy products. Testing starchy food products at the end of life for Bacillus species may be considerably more beneficial in building a true picture of product safety than testing on DOP+1.”

While monitoring food samples for disease-causing microbes happens at various stages within the food supply chain, and is often carried out by larger food processing plants, the conventional microbiology culture methodologies used to detect both pathogens as well as spoilage-causing bacteria have their limitations. “Traditional microbiology methods have long culture incubations, can face unculturable microbes and strain typing inaccuracies,” says Yowanto. “In addition, small suppliers or growers typically do not have the capability or capacity to monitor these microbes, compounding the risk of food-related sickness for consumers.”

The US Centers for Disease Control (CDC) has estimated that the majority of illnesses and deaths caused by foodborne illnesses in the US result from unknown pathogens. A new approach to controlling food safety has recently been developed by the CDC and Pulse Net. Because the first sign of a problem in the supply chain is usually the outbreak of illness, the approach works through a network of public health and food regulatory agency laboratories to connect cases of foodborne illness through molecular subtyping of a range of disease-causing bacteria. “Pulse Net has developed the multiple locus variable-number tandem repeat analysis (MLVA) fingerprinting method to identify distinct lineages of disease-causing microbes, where the MLVA profile of a microbe in a sick patient can be compared to that in a food sample to determine the source of an illness outbreak,” Yowanto explains. “The technique uses PCR to amplify the DNA repeat sequences and the PCR product is detected and separated using a high resolution capillary electrophoresis instrument. This approach enables fast and confident identification of outbreaks on an international scale, and has already helped to link illness outbreaks to a single common source in numerous cases, and detected unknown food safety issues in many products, including beef, peanuts, produce, eggs and spices.”

Allergen contamination
But foodborne diseases aren’t the only reason to test foodstuffs. Food sample testing is routinely carried out throughout the supply chain to firstly check food quality, for example to confirm the identity, origin and purity of ingredients; and secondly food safety; such as screening for banned or restricted substances like pesticides, additives and allergens.

“As the food industry becomes increasingly globalised, more and more ingredients from different countries are entering the supply chain,” says Yowanto. “While processes for monitoring certain pathogens in processed foods may be well-established, the increasing transportation of fresh produce such as fruit and salads can be problematic, because these are difficult to trace, to monitor and to keep safe.”

And businesses of course need to consider which tests they need to carry out to enable them to produce safe, quality-assured food. “From shelf life, nutritional analysis, label validation and microbiological testing to contamination, allergens, speciation identification and chemical testing, the list is endless,” says Harvey. “EU regulations have been put into place in order to not just protect the customer, but to also guide organisations in implementing effective food safety practices within their businesses.”

When it comes to managing allergen contamination, for example, it is important to firstly carry out a risk assessment for HACCP, which identifies areas in the process where control is essential in order to prevent or eliminate a hazard, or to reduce it to an acceptable level (i.e. critical control points). It is also important that criteria are established which separates acceptable from unacceptable hazards in order to ensure prevention, elimination or reduction of allergens. This information can be used to prepare an effective allergen monitoring and management plan and to establish corrective actions when a critical control point is not under control.

“Sampling should be based on the risk assessment which takes into account handling and processing,” says Claire Milligan, Product Manager at R-Biopharm Rhône. “For example, foods which are always strictly separated and so have no risk of contamination by allergens would only need to be tested on an infrequent basis for conformation, while equipment that is frequently used or where allergens are part of the process should be checked more frequently at points identified by the allergen management plan.”

When it comes to detecting the presence or absence of residual allergenic substances, the analytical techniques used will vary. The ‘physically and visually clean’ standard will form the basic starting point and once it has been validated by one of the methods discussed, can provide the basis of sound allergen management.

 “For food preparation areas, simple screening tests such as dipsticks or Lateral Flow Devices (LFD) can be used where routine verification of cleaning checks is required, and can be carried out on site,” explains Milligan. “The LFDs give a simple coloured reaction which can be easily read by eye and cost wise are lower than other quantitative methods. However, they provide valuable information on the efficiency of the cleaning process in areas where allergens should not be present.”

Sample types tested will depend on the process or what is being monitoring in a food or drink manufacturing plant, but they tend to fall into four broad categories:
1.The finished product: to show the effectiveness of all cleaning procedures
2.Swabbing of any contact surfaces: to monitor any residual allergens
3.Air samples or settle plates: to monitor any dusting
4.Flushing or purge materials: to monitor where wet cleaning is not appropriate.

“For ingredients, finished product or the validation of any cleaning process, a more sensitive, quantitative ELISA (Enzyme Linked Immune-sorbent Assay) test should be used,” says Milligan. “ELISAs are used widely in laboratories throughout the food industry along with food control organisations to quantify and defect the presence of allergens in food. Both LFDs and ELISAs are routinely used to form a robust platform for effective allergen management.”

While food sampling and microbial screening at large food processing plants will continue to be critical for food safety, alternative approaches such as bacterial fingerprinting can play a vital role in limiting the impact of foodborne illnesses, and help food industry suppliers to prevent future occurrences.

“It is, ultimately, the responsibility of organisations within the supply chain to get their products to market, ensuring that they are safe, legal and market compliant, through all stages of the product life-cycle and beyond,” says Harvey. “This can be achieved through regular and frequent testing, meeting food safety regulations in local and international markets, effective auditing programmes and the implementation of best practices. Global consumer confidence is increasing, as it the demand for safe and high-quality food. Delivering this should be the core of an effective supply chain, ensuring the survival of a prosperous food industry.”

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