Obtaining thermal images of creole corn by means of photoacoustic microscopy

Abstract

The use of non-destructive techniques, such as photothermal techniques, can be used for characterization of non-homogeneous materials with different components and thermophysical properties. Among the photothermal techniques, the photoacoustic microscopy (PAM) has been used to obtain thermal images of different samples, ranging from semiconductors to biological materials. In the present study, the thermal imaging of six different creole corn varieties was obtained by using PAM. According to the color, these varieties were nominated as M1 (orange–yellow), M2 (blue), M3 (blue), M4 (light yellow), M5 (yellow), and M6 (red). Thermal images allowed us visualize corn characteristic features and structures, with higher values of photoacoustic signal amplitude in floury regions and pedicel. The highest values of photoacoustic signal amplitude corresponded to M1 (0.39), M6 (0.35), and M5 (0.34) corn samples, followed by M4 sample. Also, colorimetric parameters L*a* and b* of the creole corn samples were evaluated, and they showed significant statistical differences (p < 0.5). The colorimetric results were analyzed by the statistical method of Kernel density estimation, showing a higher density of data in the B component, followed by R and G. The non-destructive techniques allow characterizing non-homogeneous materials with different components. Thermal images, obtained by using PAM, can be analyzed by several statistical methods.