How Isotope Fingerprinting Helps Verify Food Authenticity & Fight Food Fraud

Have you ever thought about the authenticity of the food you are buying? Maybe asking yourself, is it truly organic and was it really locally produced? In the end, it is quite difficult to judge where and how a product was produced.

In recent years, consumers have been increasingly demanding informative labels of food origin and authenticity. Generally, the label or description of food must provide trustful details of its ingredients, geographical origin, processing technology, production years and genetic identity. An authentic food must strictly comply with a declaration by the producer. The information given by the food label description is essential for consumers to make decisions about their diet and the food they buy.

What is the definition of food fraud?

Food fraud is defined as intentional deception using food for economic gain. The deliberate adulteration and providing misleading information to any part of the food supply chain will cause food fraud. The commission of food fraud commonly includes counterfeiting, mislabeling, adulteration, substitution, addition, dilution, gray market, tampering, mislabeling of food ingredients, or food packaging.

Here’s a simple example that may affect each of us. Organic food fraud or wrong declaration of origin are “potential” problems in a food market. The price of organic or local food is typically much greater than food produced by conventional practices or shipped from low-income regions. Substitution with conventionally produced food gives producers a motivation for fraudulent activities to gain greater profits. The use of fertilizer, for example, is a key factor that organic farmers must consider. The lower efficiency of organic fertilizers may create incentives for producers and distributors to increase yields by planting vegetables with artificial fertilizers or mislabeling of conventional vegetables farmed somewhere else around the globe to catch up with rising demands.

The global food supply system is expanding, becoming more complex, and the supply chain is lengthening. This makes tracing of origin and authenticity of food, feed and beverages a challenge. In this case, companies need to pay more attention to the potential for food fraud and effectively help their customers discriminate and reduce the risk of fraud. Thus, verifying food authenticity plays a key role in ensuring consumer health, protecting consumer rights, preventing fraudulent product and deception in trade competition, and maintaining sustainable development of national agricultural resources.

Which techniques are available for food authenticity and traceability?

There are many modern techniques for food authenticity and traceability, such as radio-frequency identification (RFID), near-field communication (NFC), isotope analysis, and DNA barcoding, just to name a few.

Isotope ratio mass spectrometry (IRMS) has been used to detect fraud in food production since the early 1970s. In recent years, stable isotope analysis has gained increasing attention in control of food quality and provenance due to the high efficiency and precision of this method. Generally, the isotope analysis focused on three aspects of food authenticity and traceability:

discrimination of food adulteration
tracing the geographical origin of food productions
verifying organic food

Another tool for quality control in the food cycle is elemental characterization. Elemental analysis utilizes carbon, hydrogen, nitrogen, sulfur and oxygen, which help determine the structure of an unknown compound, as well as to evaluate the structure and purity of a synthesized compound.

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How can isotopes be used to determine origin and authenticity?

Food and beverage products have a fingerprint, a unique chemical signature that allows the product to be identified. To visualize this fingerprint, IRMS can be used hyphenated to an elemental analyzer (EA) or gas chromatograph (GC), identifying the isotope fingerprint of the product. The isotope fingerprint in food and beverage products is region or process specific, which means that products can be differentiated based on:

geographical region (cheese, coffee, sugar, fish and animal feeding areas)
botanical processes (beans, seeds, olive oil, vanilla)
soil and fertilization processes (fruits and vegetables)
fraudulent practices (sugar addition to honey, watering of wines and spirits)

These processes can be traced using carbon, nitrogen, sulfur, oxygen and hydrogen isotopes, with their variations indicating the origin and history of food and beverage products.

Table 1: Isotope fingerprints in food and beverage products.

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Which technical tools are required for elemental and isotope analysis?

There are several approaches to performing isotope analysis. However, the fundamental process for IRMS is the conversion of a solid or liquid sample to a gas under high temperature. In the case of EA-IRMS and GC-IRMS the conversion of the sample to a gas is performed by two processes: combustion and pyrolysis. Combustion is used to evolve carbon, nitrogen, and sulfur from the sample in the form of N₂, CO₂ and SO₂. Here the sample is oxidized (burned) at around 1000 ˚C with additional oxygen. Pyrolysis is used to evolve hydrogen and oxygen atoms from the sample into H₂ and CO gases at 1400 ˚C. After the gases are produced, they are separated from one another using gas chromatography and then transferred in a continuous gas flow to a detector that measures the isotope fingerprint of the sample.

Are there official methods for origin, authenticity and label claims in food and beverage products?

Standardized methods and official international methods exist for stable isotope analysis of food and beverage samples and serve to verify product origin, authenticity, and label claims. These official methods, alongside the analytical solutions, are listed in Table 2. These methods have been formalized to create standardized approaches to sample analysis between laboratories, allowing laboratories to obtain conclusive answers for consumers, manufacturers and governmental bodies, pursuing food and beverage adulteration and fraud.

Table 2. Official methods for isotope analysis using isotope ratio mass spectrometry.

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The power of isotope fingerprinting

Isotope analysis has proven to be a powerful tool in the authentication and traceability of food production. The techniques of isotope analysis have several advantages, for example, high precision in the methods — which can provide clear and strong evidence for food authentication that cannot be obtained using other analytical techniques — the need for small samples, and the fact that the same technique can be used for almost any type of food production. Overall, isotope analysis has been applied in food studies as recorders of various environmental, chemical and biological processes. Additionally, recent technological advances in isotope analysis technology have introduced the possibility to perform simultaneous rapid multiple-element isotope ratios analyses. And this further expands the applicability of isotope fingerprinting, in general. The combination of multi-element isotope analyses with other analytical methods (e.g., multi-element analysis, DNA barcoding and chemometrics) have also been reported to provide higher discriminative power and are currently gaining increased attention in food traceability studies and applications. Conclusively, the tools for elucidating food fraud are available and will likely find their way into routine quality labs, which will help protect customers and distributors.