Maturity Prediction in Yellow Peach (Prunus persica L.) Cultivars Using a Fluorescence Spectrometer

Abstract

Technology for rapid, non-invasive and accurate determination of fruit maturity is increasingly sought after in horticultural industries. This study investigated the ability to predict fruit maturity of yellow peach cultivars using a prototype non-destructive fluorescence spectrometer. Collected spectra were analysed to predict flesh firmness (FF), soluble solids concentration (SSC), index of absorbance difference (IAD), skin and flesh colour attributes (i.e., a* and H°) and maturity classes (immature, harvest-ready and mature) in four yellow peach cultivars—‘August Flame’, ‘O’Henry’, ‘Redhaven’ and ‘September Sun’. The cultivars provided a diverse range of maturity indices. The fluorescence spectrometer consistently predicted IAD and skin colour in all the cultivars under study with high accuracy (Lin’s concordance correlation coefficient > 0.85), whereas flesh colour’s estimation was always accurate apart from ‘Redhaven’. Except for ‘September Sun’, good prediction of FF and SSC was observed. Fruit maturity classes were reliably predicted with a high likelihood (F1-score = 0.85) when samples from the four cultivars were pooled together. Further studies are needed to assess the performance of the fluorescence spectrometer on other fruit crops. Work is underway to develop a handheld version of the fluorescence spectrometer to improve the utility and adoption by fruit growers, packhouses and supply chain managers.

Light and Autofluorescence, Multitasking Features in Living Organisms

“…An approach based on UV excitation and cryo-imaging of autofluorescence in apple and grape tissue slices has allowed the topological localization of chlorophyll and flavonols in cuticle and cell walls, as a helpful technique to assess fruit quality and resistance to biotic and abiotic stress [93]. A fluorescence nondestructive spectral analysis of some cultivars of yellow peaches has also shown that fruit ripening is accompanied by a decrease in the signals typical of chlorophyll, the 683, 820 nm bands, and of flavonols and carotenoids, the 450-600 nm spectral region, in parallel with an increase in the band in the 600-650 nm range, consistently with the fluorescence spectral position of anthocyanins reported in the literature for grapes or onions [83,94,95]. Similarly, the content of anthocyanins estimated indirectly from the ratios of chlorophyll fluorescence measured in situ under different excitation wavelengths, by means of a portable fluorometric sensor device, has been proposed to optimize the harvest time for the table grape, Crimson seedless cultivar [96].…”

Reliability of a Handheld Bluetooth Colourimeter and Its Application to Measuring the Effects of Time from Harvest, Row Orientation and Training System on Nectarine Skin Colour

“…Both a* and h • are likely to be good indicators of maturity, with the latter being, in theory, the ideal parameter in fruit that possess a yellow intermediate step in the shift between green (immature) to orange-red (mature) or in fruit that simply go from green to yellow during ripening. Flesh a* and h • were strongly correlated with maturity in yellow peach cultivars [15]. In peaches and nectarines, fruit skin colour is influenced by environmental factors such as light [16][17][18] and irrigation [3,19].…”

Use of Biotechnological Methods to Support the Production of New Peach Hybrids

“…Insufficient work of the photosynthetic apparatus is associated with the addition of sucrose to the culture media and CO 2 deficiency [73,74]. Photoinhibition in peach plants and changes in the general functional state under the pressure of abiotic stress factors have been shown [75][76][77]. In our work, low photosynthetic activity and relatively low values of photosynthesis Y (II) efficiency were associated with a low chlorophyll amount in vitro.…”