Multispectral Imaging of Wok-Fried Vegetables

Quality control in the food industry is often performed by measuring various chemical compounds in the food involved. The authors propose an imaging concept for acquiring high-quality multispectral images to evaluate optical reflection changes in carrots and celeriac over a period of 14 days. For comparison, sensory analysis was performed on the same samples. Prior to multispectral image recording, the vegetables were prefried and frozen at -30 °C for 4 months. During the 14 days of image recording, the vegetables were kept at +5 °C. In this period, surface changes and thereby reflectance properties were very subtle. However, they noted statistically significant differences for some wavelengths and combinations of wavelengths. The corresponding sensory tests showed weak differences over the 14 days (significant at a 10% level of significance), which makes it the more important that the authors were able to detect minor changes using multispectral imaging. From our findings, it seems probable that oxidation caused the changes over time.