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NMR Spectroscopy Enables Food Authentication

 

“The future NMR implementation into routine practice will rely on the further exploration of  FoodScreener™ like platforms for simultaneous targeted and untargeted applications.”

Practices designed to intentionally deceive customers to increase profit margins are increasingly prevalent across the food and beverage industries. Products are being adulterated to replace the labelled product with cheaper alternatives, for example, through the addition of corn syrup to honey, or mislabeling products to increase their value, such as manuka honey or extra virgin olive oil. Concerted initiatives centered around the analysis of random samples using nuclear magnetic resonance spectroscopy are underway to eradicate such fraudulent trading.

The ability to rapidly and simultaneously analyze numerous components of complex mixtures without damaging the sample makes NMR well suited to the analysis of food and drink. This powerful technique, which is widely used for routine quality control checks throughout the food industry, is now being utilized in the battle against food fraud.

NMR can be employed for targeted analysis to identify the presence or determine the amount of a known ingredient or contaminant. This has been used to evaluate the purity of honey by quantifying the amount of the honey-specific minor sugar turanose, and to confirm that coffee labeled “100% Arabica” is indeed that and that it has not been bulked up with cheaper Robusta coffee, which is characterized by the presence of 16-O-methylcafestol (16-OMC).

However, food fraud cannot always be detected by screening for the presence or absence of a single entity and nuclear magnetic resonance also allows the identification and quantification of unanticipated adulterants.

Untargeted NMR analysis evaluates all small molecules in the sample to provide a complete chemical profile. This spectral fingerprint can be obtained for the genuine product and then used as a reference point for the identification of malpractice in samples of unknown origin.

This approach has proved a valuable tool for the verification of the purity and geographic origin of honey and for confirming the quality of extra virgin olive oil. It has also been successfully used to determine the grape variety and geographical origin of wines and to uncover counterfeit spirits.

Both targeted and untargeted NMR methodologies are thus important tools for confirming the authenticity of food and drink products and for detecting fraudulent activity.

NMR analysis is becoming more widespread across the food authentication field as accessibility to the required instrumentation has increased. Low-field NMR benchtop instruments with high resolution can now be purchased for significantly less than conventional NMR equipment and do not require a lot of space or expensive ongoing maintenance. Furthermore, they can be readily operated by personnel without expert knowledge of NMR.

Food authenticity testing using NMR has been further facilitated by the development of the NMR-based Bruker FoodScreener™. This platform uses targeted and untargeted analysis to enable the simultaneous evaluation of a range of different parameters for the determination of quality and authenticity of foodstuffs and beverages.

Specialized modules are available for the FoodScreener™ that tailor the analysis for a specific food type. For example, the Wine-Profiling™ module is designed for wine authentication and the SGF-Profiling™ module aids the screening of fruit juices.

Reference:

Sobolev AP, et al. Trends in Food Science & Technology. 2019;91:347–353. DOI: 10.1016/j.tifs.2019.07.035