An Approach for Monitoring the Moisture Content Changes of Drying Banana Slices with Laser Light Backscattering Imaging

Moisture content is an important quality attribute that directly influences storability of fruits and vegetables. The main goal of the present work was to test laser light backscattering imaging technique as a monitoring tool during drying of banana (Musa x cavendishii L.) slices. Laser diode emitting at 670 nm was used as the light source, whereas a charge-coupled device camera served as detector. The photon migration into the tissue was recorded as the average profile of the intensity gradient and expressed by two parameters, the size of the total illuminated area (square centimeters) on the surface and the radius (centimeters) of this area. The two attributes correlated with each other (r=0.97-0.98). Backscattering images of slices were acquired each hour during the drying process at three different temperatures: 53, 58, and 63 C. The two parameters of the intensity profile responded sensitively to changing moisture content. Significant relationship was found between changes in backscattering area and moisture content, especially at lower temperatures (r=0.76, T=53 degrees C), when almost no tissue browning occurred. At higher temperatures, correlations were observed between the parameters extracted by image processing and a*