Visualization of Sugar Distribution of Melons by Hyperspectral Technique

Publisher Summary This chapter discusses the development of a technique for visualization of the sugar content of a melon by applying near-infrared (NIR) spectroscopy to each pixel in an image. The relationship between the sugar content and absorption spectra can be investigated by using a NIR spectrometer to visualize the sugar content of a melon. The absorbance at 676 nm, which is close to the absorption band of chlorophyll, exhibited a strong inverse correlation with the sugar content. A high-resolution cooled charge-coupled device (CCD) imaging camera fitted with a band-pass filter of 676 nm was used to capture the spectral absorption image. The calibration method was used for converting the absorbance values on the image into the oBrix sugar content in accordance with NIR spectroscopy techniques. When this method was applied to each pixel of the absorption image, a color distribution map of the sugar content could be constructed. In addition, a method for visualizing the sugar content based on the sugar absorption band was also developed. This method can avoid bias caused by the color information of a sample. NIR spectroscopic analysis revealed that each of the two second-derivative absorbances at 874 and 902 nm had a high correlation with the sugar content of melons. A high-resolution cooled CCD camera with band-pass filters, which included the above two wavelengths, was used to capture the spectral absorption image of a half-cut melon.