Tomatoes Maturation Analysis with Reflectance Spectral Images

Abstract

The demands for high quality products are increasing in the market, so several tests are performed. These analyses are destructive, time consuming and sometimes expensive. The spectral imaging technique is an alternative that can reduce costs and time and increase the efficiency and cost-effectiveness of these analyses. In this context, the aim of this study was to verify the spectral behavior of the tomato in function of the maturation and its potential use for non-destructive evaluation of food quality. Eighty tomatoes of the Italian group were selected in four stages of maturation (green, pink, light red and red). Images were collected in wavelengths 480 nm to 710 nm (every 10 nm). After the images were collected, the fruits were submitted to the physical-chemical analyses. The following parameters were analyzed: color, color index (CI), pH, soluble solids (SS), total titratable acidity (TTA) and ratio (SS/TTA). After characterization the mean spectrum was obtained by the extraction of the spectral characteristics. It was observed that the spectral behavior was the same for all stages of maturation. It was possible to differentiate the green tomatoes in the wavelengths from 520 nm to 560 nm and from 610 nm to 660 nm. These intervals represent the area of reflection of chlorophyll and lycopene, respectively. Near the wavelength 560 nm, the highest absorbance was recorded by ripe tomatoes due to the concentration of lycopene. It is concluded that the best wavelengths for analysis are those in which green has the highest reflectance and it is possible to apply this technique for non-destructive analysis of the maturation of tomatoes.