Editorial Feature

Spectroscopy Methods Used to Combat Food Fraud

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Food fraud is a complex issue that is difficult to combat. Horse meat and melamine scandals occur when traceability of the food chain breaks down and potentially harmful products enter the food supply chain.

Fraud can happen at any stage of the industry, including in the production of raw materials, the final product and the packaging containing the food and drink.

Spectroscopic techniques can be used to test food products at various stages of the supply chain to prevent fraud.

Types of Food Fraud

The types of food fraud include:

  • Dilution: Mixing an ingredient of high value with that of a lower value
  • Substitution/ Unapproved enhancement of products: Nutrients and ingredients are replaced for those of a lower value. Economically motivated adulteration (EMA) is the term used to describe intentional modification or substitution, which is carried out to gain profit at the expense of the public.
  • Addition/concealment: Undeclared products may also be added and concealed to enhance products or produce them on a cheaper scale illegally.
  • Mislabelling: Items being deliberately labeled with false information due to ingredients being substituted for similar, cheaper products are also a common problem that the food industry faces.
  • Contamination

Examples of Food Fraud

The most common areas of the food and drink industry that have been affected by fraud include oils, milk, baby formulas, meats, juices, spices and honey.

The most famous scandals that have caused new legislations to be put in place include:

  • Rapeseed oil scandal: Back in 1981, rapeseed oil in Spain had alanine removed from it and was falsely sold as regular olive oil.
  • Melamine scandal: Melamine was added to milk and baby formula in China to make it appear to have a higher protein content. Melamine was also found in pet food and chickens in America.
  • The horsemeat scandal: Beef products were found to contain undeclared horse meat
  • The Zaman Manslaughter: Indian restaurant owner Mohammed Zaman substituted almonds for cheaper, groundnut recipes that contained peanuts, causing the death of a customer after a severe anaphylactic shock.
  • Olive oil fraud: Seven major olive oil companies were found to be fraudulently claiming their virgin olive oil was extra virgin olive oil.

It is not just the famous scandals that are affected by food fraud. Many household products such as fruit juices, parmesan and oregano are regularly targeted by fraud through dilution, addition and substitution of products not listed.

Spectroscopy as a Way to Combat Food Fraud

Spectroscopy is a set of analytical techniques that identify the composition and structure of an analyte by the interaction between electromagnetic radiation and matter.

The interactions cause electronic excitations, molecular vibrations and nuclear spin orientations which can be analyzed with different spectroscopic instrumentation. The types of spectroscopy that are used to detect and prevent food fraud include fluorescence spectroscopy, infrared (IR) and Raman spectroscopy, as well as NMR spectroscopy.

Fluorescence Spectroscopy

Fluorescence spectroscopy analyses compounds by using a beam of light to excite the electrons in the compounds. The excitation causes them to emit light, which is then detected and recorded.

Fluorescence spectroscopy has a very low limit of detection compared to other spectroscopic methods, but it is an excellent technique to investigate polyaromatic hydrocarbons (PAHs) and heterocyclic compounds non-destructively.

Click here to find out more about fluorescence spectrometers.

This type of spectroscopy is a common way of analyzing oils, including olive oils, rapeseed oils and walnut oils. Fluorescence spectroscopy can be combined with infrared spectroscopy for more in-depth analysis with Fourier Transform Infrared Spectroscopy (FTIR).

IR Spectroscopy

IR spectroscopy uses the infrared spectrum to analyze compounds. IR spectroscopy involves a beam of light passing through the sample, causing the molecules of the sample to vibrate and the bonds to stretch and absorb infrared radiation.

If the IR frequency is the same as that of the vibrational frequency of the bonds, absorption will occur and the spectrum will be recorded. The technique can be split into near IR, mid-IR and far IR, with near IR having the greatest energy and penetration of samples.

IR spectroscopy is the most common method used to detect food fraud.

Click here for more information about the diverse range of spectrometers available.

Milk, honey, meat, cheeses, fish, spices and oils can all be analyzed using both near and mid-IR. A type of IR known as FTIR is used to investigate the physical and chemical properties of food, such as the trans-fat content of manufactured food products by infrared attenuated total reflectance (ATR), comparing differences in grains of wheat varieties and identifying foodborne pathogens.

Raman Spectroscopy

Raman spectroscopy is another type of vibrational spectroscopy, but instead of the bending and stretching of bonds, it uses inelastic scattering of monochromatic light.

The scattering provides a molecular fingerprint of the structure and chemical composition of samples. A disadvantage of Raman spectroscopy is that Raman scattering gives weak signals, but it can be enhanced with techniques such as Surface Enhanced Raman Spectroscopy (SERS).

Using Raman spectroscopy over IR spectroscopy eliminates the problem of interferences from water that is often found in food products, because water has a weak Raman scatterer.

Another significant advantage of using Raman spectroscopy to detect food fraud is that it can be used to analyze food directly through glass or plastic packaging.

Handheld Raman spectrometry can be used to check products through the packaging through non-destructive, quick detection of fraud at the various stages of food and drink production.

NMR spectroscopy

Nuclear magnetic resonance (NMR) is a technique that uses resonance and the nuclear spin states of samples for analysis. Nuclei have a nuclear spin with a spin behavior that is dependent on the intramolecular environments.

If the nuclei of elements end up in differing chemical surroundings within the same molecule, various magnetic field strengths occur due to the shielding and de-shielding of electrons. It is the different resonant frequencies that determine the chemical shifts.

One of the main areas using NMR spectroscopy to fight food fraud is NMR fingerprinting to analyze wine and juices. The samples are analyzed and compared to large databases of genuine products. Information that can be gathered not only includes what components the wines and juices contain, but also details such as soil composition can show geographical origin to confirm if the wine is genuinely from the area of the world companies claim it is from.

References and Further Reading

Petronijević, R., Velebit, B. and Baltić, T. (2017) Shedding light on food fraud: spectrophotometric and spectroscopic methods as a tool against economically motivated adulteration of food. IOP Conference Series: Earth and Environmental Science, 85, p.012024. Available at: https://iopscience.iop.org/article/10.1088/1755-1315/85/1/012024/pdf

European Commission. Food fraud: What does it mean? [Online] Available at: https://ec.europa.eu/food/safety/food-fraud/what-does-it-mean_en (Accessed on 5 June 2020).

Bruker. NMR Food Screening. [Online] Available at: https://www.bruker.com/products/mr/nmr-food-screening.html (Accessed on 5 June 2020).

Dasenaki, M., & Thomaidis, N. (2019) Quality and Authenticity Control of Fruit Juices-A Review. Molecules, 24(6), 1014. Available at: https://doi.org/10.3390/molecules24061014

Saul, L. (2018) IR Versus Raman - The Advantages and Disadvantages. [Online] AZoOptics. Available at: https://www.azooptics.com/Article.aspx?ArticleID=1291 (Accessed on 5 June 2020).

Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.

Louise Saul

Written by

Louise Saul

Louise pursued her passion for science by studying for a BSc (Hons) Biochemistry degree at Sheffield Hallam University, where she gained a first class degree. She has since gained a M.Sc. by research and has worked in a number of scientific organizations.

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