New food imaging technique improves food safety efforts

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A study in the Journal of Food Science shows that near-infrared (NIR) wavelength signals can be used to image many different types of food products, and to provide measurements for the detection of foreign bodies and in food quality monitoring. Some of the most widely used methods for investigating properties of foods include metal detection, X-ray techniques, and visual inspection. However, each of these methods has disadvantages. In this study, the researchers used a through-transmission NIR imaging system using a single NIR wavelength of 850 nm to image the internal structure of many different types of food material.

The researchers imaged frozen dough products; these products can be a problem for metal detection due to the ice layer on the outer surface of the sample that can have a finite conductivity. Using NIR imaging, researchers were able to detect the presence of a coin and a glass ball inside frozen dough products. NIR signals can also be used to inspect food materials with a high percentage of water content, such as fruits and vegetables.

The NIR imaging technique can also be used for packaged foods, as long as no metallic layers are present. For example, the researchers were able to detect a piece of adhesive that was placed between two layers of a meat sample, which was inside standard plastic packaging that included a layer of paper at the base of the container. Detection of bones and fat in meat-based products is also possible with this technique. In fact, NIR at 850 nm could be used to determine the percentage of fat content in meat products, where all other components are constant.

The researchers concluded that NIR imaging presents clear benefits in the case of food materials, where transmission through certain foodstuffs (such as bread dough) is possible where ultrasound cannot be used effectively. NIR imaging is nonionizing and potentially low cost, giving it an advantage over X-ray inspection methods in certain applications.




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