To be able to detect foreign objects in foods on factory production lines is important for our health and safety and is normally performed using an X-ray computed tomography apparatus or a metal detector. Dense materials such as a piece of stone or metal can be easily detected, and foods containing them are removed from the production lines.

However, foreign organic objects in foods cannot be detected with this equipment, and so the need for new techniques to detect them has been around for some time.

Now, Mitsuo Fukuda and his colleagues in TUT and Aichi Science & Technology Foundation, have developed novel real-time NIR optical imaging systems comprising a two-dimensional (2D) optical source composed of 850-nm-wavelength-band LEDs, a CMOS sensor, and optimized optical systems. The optical system accurately detected organic objects such as a human hair, part of an insect, plastic, and a piece of rubber in a piece of 5-mm-thick chocolate in real time. Additionally, the bone structures in chicken wings of about 20-mm in thickness were also able to be detected.

The author Prof. Mitsuo Fukuda said "We only developed some basic techniques and systems for a real-time optical imaging system for detecting foreign organic objects and will need to customize them for application to each type of food in the future”.

The developed real-time NIR imaging system will be applicable for the observation of internal images of moving samples such as foods in mass-production lines in factories with high spatial resolution. Consequently, this system will promote food safety and security in our daily lives.