- Deducing the geographic origin of a substance and its ingredients by analyzing the stable isotope ratios of hydrogen, oxygen and carbon contained in the substance -
False labeling of imported foods as "Made in Japan" has been a social problem, causing consumers to be worried about food safety and the accuracy of information regarding the geographic origin of food. The government and municipalities are stepping up their efforts to protect food brands. Food companies are performing various inspections to assure customers of the safety of their products. It takes about a week to deduce the origin of a product with existing scientific analysis technology, and so it is difficult to integrate those inspections into the logistics process.
NTT has a solution. Our analysis technology using highly sensitive semiconductor lasers helps perform the following checks much faster than conventional techniques. We created this unique technology based on the laser light sources we have developed for optical communications.
Atoms have different mass numbers, which indicate the weight of the atom, despite being atoms of the same element and having the same number of protons. These atoms are called isotopes. A lot of information can be obtained about the origin of materials by precise measurement of the isotope ratio. Food is evaporated or burned, turning the hydrogen (H), oxygen (O) and carbon (C) in the food into gases, including steam (H2O) and carbon dioxide (CO2). When gases are irradiated with laser light, the gases absorb the light. As a highly sensitive semiconductor laser is used, it is possible to detect subtle differences in absorption wavelength between isotopes and the amount absorbed by each isotope, thus making it possible to analyze the isotope ratio of elements in the gases. The stable isotope ratio of rainwater (H2O) is known to vary from region to region. The stable isotope ratios of hydrogen and oxygen, which are the components of plants and animals, are influenced by the water in the regions where they have grown. By determining the stable isotope ratios in food, it is possible to deduce the country of origin of the food.
This technology is capable of analyzing very low ratios of stable isotopes fast and accurately. Compared with conventional techniques, the technology does not require much calibration and maintenance, thus reducing labor and costs. In addition, the technology is compact: we have built a portable analysis system.
Laser gas sensing technology
*δ value: Difference between an isotope ratio (e.g., D/H and 18O/16O) in a sample and that in a standard, expressed per mil (‰)