DNA Testing: Serving Authentic Food

With the numbers of food scandals on the rise, consumers are more than ever concerned about the origin and source of their diet. Industry members and officials have responded with different measures such as extensive labelling and stricter controls. However, together with the higher demands on safety, food fraud has become increasingly widespread.

More than 150 instances of deliberate substitution, addition and misinterpretation of food, food ingredients or packaging have been reported in recent years, reports for example AT Kearney in its 2010 research ‘Consumer Product Fraud: Deterrence and Detection’. According to the study, the cases have cost the industry $10bn to $15bn every year – but the loss of consumer trust and confidence is a far greater price to pay.

One possible solution to identify food adulteration on a regular basis has been found in the use of DNA testing to help verify the authenticity of foods and their ingredients. With the food authenticity programme of the UK Department for Environment, Food and Rural Affairs (Defra) the government boosted the use of the forensic method in 2010 and 2011.

Leading in the use of DNA sequencing to verify the authenticity of foods and their ingredients is the international science-based company LGC, based in London, UK. In February this year, the company provided training to UK public analyst laboratories. The instructors offered information on how to use DNA sequencing to determine the presence of particular species of fish, meat, and fruit and vegetable products used as foods or present as ingredients in food samples, as well as to identify species that are not included in tests that are currently available to public analysts.

Here, the company’s science leader of food analysis, Malcolm Burns, speaks about the next generation of DNA sequencing, the cost of testing food and the dangers of food fraud for the industry and its customers.

Elisabeth Fischer: How do you test the DNA of food?

Malcolm Burns: In its most basic form the process of DNA sequencing allows the breakdown of DNA information into its individual four component base pairs A, T, G, C. These bases are then matched to validated sequence information through available DNA databases to allow identification of the species or variety of the food ingredient.

At LGC the process of analysing the DNA from food ingredients involves ensuring a representative laboratory sample of the food is taken and that DNA is efficiently extracted from this sample. We can use a wide variety of methods and laboratory instruments for the latter.

Short sequences of DNA, called primers, are then selected and will amplify the target region of the DNA species of interest in a process called the polymerase chain reaction. The primers and the amplified DNA target region are then used for the DNA sequencing process, and the resulting DNA sequence can then be compared with DNA sequences of proven species identity using available databases.

EF: What have been the biggest advances in the DNA sequencing of foods and their ingredients in the past few years?

MB: The term ‘next generation sequencing’ is often used in relation to a number of new sequencing technologies and instruments used for DNA sequencing. This term encompasses a range of DNA sequencing approaches that exhibit different characteristics and performance parameters.

The majority of these next generation sequencing technologies share common features resulting in higher sample throughput, lower costs associated with DNA sequencing analysis, the ability to simultaneously sequence lots of individual DNA molecules, and the capacity to analyse mixed DNA populations at the same time and hence differentiate mixed food ingredients present within the same sample.

EF: What are the costs of DNA testing for food products?

MB: With the advances in modern molecular techniques and the availability of modern DNA sequencing being offered by a number of commercial service providers, the costs of DNA sequencing are now very competitive. In its simplest and most basic form, DNA sequencing can cost just a few pounds for one sequence read in one direction, forward or reverse, of the DNA strand.

With the more advanced approaches offered by next generation DNA sequencing technologies and their associated advantages, the costs will rise accordingly. As with any result, one must also take into account the need for doing replicate DNA sequencing runs in the forward and reverse direction of the DNA sequence to add further confidence in the data.

EF: What type of food ingredients can be tested?

MB: DNA sequencing can potentially be applied to any food ingredient from which DNA can be successfully extracted. Common examples include, but are not limited to, confirming the identity of ingredients such as British and European meats, exotic imported meats, pasta, Basmati rice, fruit juices, fish species, potatoes, the presence of pathogenic bacteria or allergenic ingredients in foods, verifying species identity of probiotic bacteria in food, and confirming the presence or absence of genetically modified material.

EF: In your opinion, what impact has food fraud had on the economy and on society in general?

MB: With the market for top-grade food products valued in the multimillion pounds mark, premium food ingredients are commanding higher prices. The opportunity to reap increased profits from these price hikes inevitably means there is a greater likelihood of fraudulently labelled food penetrating the market.

For instance, high-value ingredients such as meats are at a relatively high risk of fraudulent replacement with cheaper species or cuts. At the same time, the current economic downturn also dictates that there is an increased propensity for adulteration of food ingredients used in lower grade products.

Food fraud undermines value for money for a number of stakeholders including the consumer, legitimate food businesses and the UK economy as a whole. Correct labelling of food products for their ingredients is therefore an important tool to protect UK trade and industry. It is also critical in facilitating consumer choice based on health, religious and cultural reasons. For instance, the presence of allergenic ingredients in foods that have not been labelled or identified correctly can have devastating health consequences.

Novel and exotic animal and plant products are also becoming increasingly available on the EU market, highlighting the need to provide unequivocal identification of species present in food samples. More accurate identification of food ingredients will potentially lead to better labelling schemes and facilitate greater consumer choice and protection whilst safe guarding legitimate UK trading activities.

EF: Is DNA testing the technology to battle food fraud in the years ahead?

MB: DNA sequencing is a valuable advanced confirmatory technique that gives added confidence and more information than some traditional molecular biology techniques for battling food fraud. It can be used to confirm the results of existing methods to detect food ingredients and species, as well as to identify species that are not included in current molecular tests.

LGC already offers a comprehensive DNA sequencing service for a range of products, including food, to customers including food processing companies. We focus on applying a number of approaches to cases involving food fraud, including methods for detection of DNA and proteins alongside the techniques of mass-spectrometry and microscopy. In this respect, DNA sequencing will provide an invaluable tool to use in the battle against food adulteration and to help confirm the authenticity of food ingredients.