Abstract
Highly accurate sensing for a temporal change in the freshness of brown rice was investigated using a chemiluminescence measurement. The experimental setup was composed of a dark box, a highly sensitive cooled CCD camera (HAMAMATSU, C4880), and a personal computer for data processing. The chemiluminescence intensity was estimated by using a photon counter (HAMAMATSU, C8801). Some pieces of brown rice were placed in the chemiluminescence measurement system. Two kinds of rice, such as new and old ones (stored at one year), were used for chemiluminescence measurements. The addition of 2-methoxyphenol, which is a substrate of peroxidase (POD), led to a decrease in the chemiluminescence intensity of brown rice. Therefore, the luminescence observed may have originated from the POD in brown rice. The chemiluminescence intensity of new rice was fifty-times larger than that of old rice. An increase in the storing period of brown rice at room temperature led to an extreme decrease in the chemiluminescence intensity. Further, the mixture of old and new rice could be distinguished by chemiluminescence imaging. Thus, the chemiluminescence measurement will be a useful technique to evaluate temporal changes in the freshness of brown rice.
