Food fraud in focus: Scientists devise sensor to tackle honey adulteration

17 Oct 2023 --- Scientists in China have developed a sensor that they claim can detect water adulteration in honey, one of the most exploited food items. The system is compact and consists of a microwave microstrip line planar resonator sensor tool assembled on a dielectric substrate to detect contamination in honey.

The scientists will extend the research to detect adulteration in other liquid products and create more sensitive sensors for quality control and food safety.

The study, published in Review of Scientific Instruments, highlights that direct adulteration of honey is more common due to the minuscule difference in taste when honey is added with a syrup that has a similar ingredient profile. This leads to a “strong concealment, presenting a great challenge to the detection of honey adulteration.”

The dielectric substrate used in the sensor works by insulating and supporting electrostatic fields, such as ceramic or glass. 

“On top, there are three thin copper strips separated by two gaps. The length of the middle strip and the electric field intensity at the gaps determine the resonance frequency of the device,” explain the researchers.

“When we add water to honey, it changes how the electromagnetic field behaves around it. When placed in the sensor, adulterated honey shifts the sensor’s resonance frequency. By measuring this shift, we can detect water adulteration in honey,” explains Zhen Li, author of the study at the Nanjing University of Aeronautics and Astronautics (NUAA), which conducted the study.

“This sensor provides a cost-effective and efficient method for the food industry to ensure honey authenticity.”

The study took place at NUAA and the Hebei University of Technology in China and asserts that it is imperative to develop a “rapid, effective and comprehensive” detection method for honey adulteration, which is of great significance as studies indicate it is rich in antioxidants like flavonoids and polyphenols, offering nutritional and health benefits.

Simplifying adulterant detection
According to the researchers, standard detection methods of honey adulteration are expensive and either have complicated operation methods or low detection accuracy.

For instance, using antennas in other methods, like the coaxial probe technique, needs intensive analysis of the detection sensitivity at the operating frequency, while the transmission line technique employs a “relatively complex experimental setup.” Conversely, the cavity resonator method includes a high fabrication cost. 

In recent times, the F&B industry has been monitoring food fraud cases rigorously.With their innovation, the scientists claim to have created a sensor with a simple design, compact size and low cost.

Li underscored that the team now aims to make the device work in broader applications like liquid analysis for detecting impurities or composition changes, potentially advancing sensing technology. Going further, they will explore the impact of temperature on the sensor’s performance with other liquids.

F&B v/s food fraud
As per the FAO, food fraud always concerns the quality of food, and it can be related to either the product (e.g., wood dust in coriander) or the process (e.g., selling non-halal products as halal) without intentionally affecting food safety. 

But, it can pose “a risk of food safety as a secondary effect and it can result in the product being harmful to consumers.”

The F&B has been up in arms against food fraud in recent years. Last week, Food Ingredients First reported the FSA’s efforts at curbing the malpractice, even initiating a criminal investigation on a meat scandal earlier this year.

Moreover, last year, an FAO report, “Thinking about the future of food safety - A foresight report”, highlighted food fraud as one of its emerging issues in the food and agriculture sector. It suggested monitoring the early signs of the challenges through systemic intelligence so that policymakers are better prepared to tackle them.

The role of technology in reducing food adulteration instances has picked up pace, too, with manufacturers resorting to blockchain technology to encode QR codes for enhanced traceability and transparency information in food products.

Last year, Europol’s Opson IX report on food fraud activity across 77 countries worldwide revealed 12,000 illicit food products worth approximately US$40 million were seized.

According to Kerry, low availability of key ingredients and mounting pressure on the industry to lower retail price spikes are the reason why the global food supply chain is more susceptible to food fraud and adulteration than ever.

By Insha Naureen