Correlation of Post-Harvest Avocado Ripening Process with the Thermal Emissivity Measured from the Peel

Currently, it is neither easy nor inexpensive to determine the degree of maturity of avocados in order to select the best pieces for oil extraction. There are no automatic techniques capable of determining oil content based on measurements that are non-invasive, relatively fast and non-susceptible to human error. Moreover, infrared thermography has demonstrated its ability to evaluate and characterize different systems, from solids to biomaterials; in the case of plant evaluation, it has been shown that vegetal physiological characteristics can be measured using this technique. In this study, we propose the evaluation of avocado maturity based on non-invasive and non-destructive measurement using infrared thermography. The evolution of avocado emissivity will be analyzed in the mid-infrared range through the characterization of thermal images acquired from its peel; thus, a correlation between emissivity and the avocado ripening process will be discussed. We used standard methods to determine firmness, dry matter and oil content in the peel and flesh of the fruit. We were able to correlate average values of emissivity measured from the peel with the ripening process of avocados stored at room temperature, and we identified two stages that correspond to the ripening and over-ripening processes.