Utilizing laser spectrochemical analytical methods for assessing the ripening progress of tomato

Abstract

To meet market demands and minimize losses, the tomato crop (Solanum Lycopersicum L.) requires a simple, rapid, and cost-effective method to distinguish between different maturity stages with high accuracy. This study aimed at evaluating two spectrochemical analytical techniques, namely laser-induced fluorescence (LIF) and laser-induced breakdown spectroscopy (LIBS), to discriminate three different maturity stages of tomato fruit (‘Green/Breaker’; ‘Turning/Pink’; and ‘Light-red/Red’). The simple linear regression confirmed the obtained LIF results with chlorophyll content (mg/100 g), hue angle (h°), and firmness (kg/cm2) of the different maturity stages (measured by conventional methods). Furthermore, the findings showed that the peak intensities of LIF spectra decreased with the chlorophyll content depletion during ripening. Moreover, the data exposed a reasonably good association between LIF spectra and chlorophyll content with a regression coefficient of 0.85. On the other hand, firmness and skin hue have shown an excellent predictor for the spectra with a high regression coefficient of 0.94. For LIBS spectra of each maturity stage, the ratios of Ca’s ionic-to-atomic spectral lines intensities have followed the same trend as conventionally measured firmness. The results demonstrated that LIF and LIBS are accurate, easy, and fast techniques used to define tomatoes’ different ripening stages. Both methods are useable in situ without any prior laboratory work.

A Feasibility Study on Monitoring Shelf Life of Bottled Natural Fruit Juice Using Laser-Induced Autofluorescence

“…Te observed wavelengths in this study are closely related to the spectral signatures of chemical compositions in fruits [28][29][30][31]. Molecules that exhibit numerous conjugated double bonds, for instance, carotenoids, chlorophylls, and porphyrins, show light absorption in these spectral regions.…”

“…Peaks 1 to 4 (400-600 nm) show the presence of antioxidants mainly carotenoids which are essential for the delay of oxidation in fruits [31,32]. Te antioxidants present in the BNFJ samples deteriorate with the increasing number of days causing a rise in oxidation as observed in Figure 2, whereas peaks 5 and 6 (600-750 nm) show the presence of chlorophyll pigments [28].…”