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New Sensor Can Identify Watered-Down Honey

A jar of honey with a honey stick above, held in a hand.
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Some honey is more watered-down than golden brown.

To make their profits all the sweeter, some honey producers have been known to top-up their products with water, leading to a mixed market of low- and high-quality condiments.  

To help tell the difference, researchers from the Nanjing University of Aeronautics and Astronautics and the Hebei University of Technology have developed a microwave microstrip line planar resonator sensor tool. 

Laying out their invention in Review of Scientific Instruments, the research team say their sensor tool is compact, easily made and more cost-effective than most other standard honey detectors. 

The microstrip line resonator sensor is fabricated on a dielectric substrate, which is an insulator that can efficiently support electrostatic fields, such as ceramic or glass. Three thin copper strips, separated by two gaps, lie on top; the length of the middle strip and the electric field intensity at the gaps determine the resonance frequency of the device.

“When we add water to honey, it changes how the electromagnetic field behaves around it,” author Zhen Li said. “When placed in the sensor, adulterated honey shifts the sensor’s resonance frequency. By measuring this shift, we can detect water adulteration in honey.”

Li and their colleagues tested honey samples with varying water content. They found that the sensor’s resonance frequency consistently decreases when increased water had been added to the honey.

Diagram of the experimental setup including the planar resonator sensor. Credit: Qi Jin, Zhaozong Meng, Zhijun Chen and Zhen Li.

“When choosing a honey product, my family members always have the concerns of whether it is authentic or not,” said Li. “This sensor provides a cost-effective and efficient method for the food industry to ensure honey authenticity.”

Li says the technology could be adapted to detect adulteration in many other products.

“We aim to extend our research to detect adulteration in other liquid products and develop more sensitive sensors for broader applications in quality control and food safety,” said Li, “starting with the impact of temperature on our sensor’s performance.”

Reference: Jin Q, Meng Z, Chen Z and Li Z. Sweet victory: Sensor detects adulteration in honey. Rev. of Sci. Instrum. 2023. doi: 10.1063/5.0166005 

This article is a rework of a press release issued by the American Institute of Physics. Material has been edited for length and content.