Combating food fraud has different meanings depending on whom you ask along the supply chain. For growers, it refers to protecting the integrity of the ingredients they introduce into the supply chain. For the regulatory community, it means helping to reinforce and establish the authenticity of the food market so consumers don’t have to worry about the safety of the food that they eat. For food retailers or manufacturers, it’s about maintaining their brands’ integrity and value with consumers and the industry. For everyone involved—from farm to fork—it’s about ensuring there is a continued supply of safe food around the globe.
In order to battle food fraud, it is vital to provide a host of robust analytical and informatics solutions that can detect and analyze adulterants throughout the supply chain. Techniques such as infrared (IR) spectroscopy, liquid chromatography tandem mass spectrometry (LC-MS/MS), and inductively coupled plasma mass spectrometry (ICP-MS) address food quality and safety and help consumers be more confident in the integrity of the food they eat.
First Line of Defense: UV-Vis and IR Spectroscopy
There are a number of different methods and technologies used to detect adulterants in food. The chosen method will depend on the type of food fraud that is being detected.
For example, a UV-visible light (UV-vis) spectrometer is considered a useful and simple instrument that detects adulterants in extra virgin olive oil. With olive oil consumption increasing, this high-value product has become particularly susceptible to fraud.
One example of olive oil fraud is the addition of lower grade, refined olive oils to extra virgin olive oil. These lower-quality oils contain unsaturated hydrocarbons that absorb UV light in the 200 nm-300 nm spectral range. Therefore, a high absorption within this wavelength range points to a lower quality olive oil, meaning UV-vis spectroscopy can be used to differentiate between oils in a sample.
Extra virgin olive oil can also often contain significant levels of other edible oils that have a lower market price or are of a lower quality. Some examples of common adulterants include hazelnut oil, sunflower oil, soybean oil, rapeseed oil, or corn oil. UV-vis spectroscopy offers a simple method for checking whether an analysis result is above a specific limit, and therefore whether other oils have potentially been added to a sample of extra virgin olive oil.
In situations where there is uncertainty about the type of adulteration that may have taken place, IR spectroscopy is the preferred method for rapid, onsite analysis of samples in other commonly adulterated foods like honey and orange juice. As IR spectroscopy requires little sample preparation, it is also an easy-to-implement method that is useful in providing a rapid pass/fail analysis of adulteration. This, along with the fact that it does not require significant training to be operated, means IR spectroscopy can be used for testing at any point during the supply chain.
For example, herb and spice adulteration—such as replacing oregano with olive or myrtle leaves, the addition of dyes to chili powders, or adding peanut and almond material to ground cumin powder—is rapidly becoming more commonplace in the food industry and is a prime fit for IR spectroscopy. One issue with herb and spice samples, as with most food samples, is that they typically contain many sources of natural variation and are therefore difficult to analyze. Near-IR (NIR) spectroscopy can overcome this issue, enabling deeper penetration into samples in comparison to mid-IR or far-IR. NIR can therefore produce stronger spectra, making it easier to detect adulterants in these complex samples.
By combining this instrumentation with advanced analysis technology, it is possible to compare the spectra of a specific food sample with a database of known “pure” samples. These algorithms and chemometric techniques then enable users to classify complex samples, determine authenticity, and estimate the level of a certain adulterant without the need to run a further test.
After the 2008 melamine scandal in China, detecting adulteration in milk has also become a critical application for IR analysis. Typically, milk with a higher protein content will in turn attract a higher price in the market. Unfortunately, the typical methods for testing the protein content of a milk product are based around measuring nitrogen levels. This led to the nitrogen-rich, but highly toxic compound melamine being added to milk products in order to raise their apparent protein content. IR analysis is crucial in determining the concentration of this adulterant in milk, as well as identifying any other adulterants such as sugars or urea.
Next Level: LC-MS/MS and ICP-MS
In instances of food fraud where adulterants are at too low a concentration to be picked up by IR, or where stricter regulations demand more precise determination of adulterant levels, LC-MS/MS comes into play.
In the case of milk, for example, mass spectrometry offers an alternative method for the detection of adulterants. Aside from melamine and the addition of other small molecules, large molecules can also be added to milk for the purpose of fraud—for example, diluting more expensive milks such as buffalo, camel, goat, or sheep, with cow’s milk. By using LC-MS/MS, it is possible to measure the addition of bovine milk to these pricier milks by detecting the presence of β-lactoglobulin A. (See Figure 1.) This species-specific marker protein is found only in cow’s milk, enabling users to detect the presence of this cheaper alternative in other more expensive types of milk.
A similar method can be used to detect the presence of pork in certain foods, which is crucial for consumers whose culture or religion prohibits the consumption of this meat. Pork meat, like milk, contains certain peptides that can be used as biomarkers for detection in food samples. LC-MS/MS enables the detection of these biomarkers, offering a rapid, selective, and sensitive method for analyzing raw, cooked, and processed meat products for the presence of pork.
LC-MS/MS is also crucial for the detection of synthetic azo and non-azo dyes down to 10-100 ppb concentrations. Although once used in the industry as food colorings, these dyes have now been widely banned due to their potentially genotoxic or carcinogenic properties. However, they are still being detected in the food supply chain—particularly in spices—making it crucial that sensitive methods are available for the detection of even minuscule amounts of these banned substances. First, a simple dye extraction is performed using an organic solvent, with the filtrate then injected into the liquid chromatography column. Using certain methods, LC-MS/MS can achieve exceptional chromatographic repeatability and peak resolution in under four minutes.
Additionally, LC-MS/MS can be used to detect both adulterants and contaminants in wine. As with other food products such as olive oil, additives might be introduced into wine to improve its flavor or color. There is also a high chance pesticides or fungicides could end up in the final product if the grapevines have been sprayed with these compounds during growth. Both of these additives, whether intentional or unintentional, can cause significant harm to humans if ingested. It is therefore imperative that they are detected as quickly and reliably as possible. LC-MS/MS can simultaneously determine the concentrations of both pesticides and pigments in a single analytical run, providing users with a quick and easy method for monitoring these compounds in their products.
ICP-MS can also be used to combat fraud in wine by helping to determine the geographical origin of grapes—an important factor in driving product price and consumer expectations.
Using ICP-MS, it is possible to identify the unique and varying levels of trace elements present in the wine. After an elemental profile is created by ICP-MS, informatics solutions can then deliver a visualization of the data correlating the levels of trace elements in certain wines to that in different, geographically situated soils. (See Figure 2.)
Future of Combating Food Fraud
Although food fraud is certainly not a new concept, the increasing cost of food ingredients is making it more common. This is combined with ever-stricter regulations and the fact that those committing food fraud are also becoming more creative and intelligent in finding new ways to adulterate food. It’s therefore clear that the more in-depth information available on fraudulent activity, the more effectively fraud can be reduced and controlled.
Advanced yet intuitive testing innovations will continue to play a big role in helping to combat these challenges at all points of the food chain. Informatics will also continue to emerge as an ever-critical component in the fight against food fraud. With informatics, labs, scientists, organizations, and companies have easier and more intelligent ways to visualize their data. Data can be shared more easily and securely via the cloud, and actionable insights can be drawn more quickly and easily. The food industry and solutions providers must therefore continue to work closely together to ensure optimal and advancing instrumentation and tools are being leveraged to help uphold the integrity of the food supply chain.
Sears is vice president and general manager of food, chromatography, and mass spectrometry at PerkinElmer. Reach him at Greg.Sears@perkinelmer.com. Tordenmalm is market manager for processed foods at PerkinElmer. Reach him at Stefan.Tordenmalm@perkinelmer.