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New food imaging technique improves
food safety efforts Source of Article: http://members.ift.org/IFT/Pubs/Newsletters/weekly/nl_021109.htm 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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