Determination of ‘Palmer’ mango maturity indices using portable near infrared (VIS-NIR) spectrometer

Abstract

Palmer' mango cultivar is a late season variety which is greatly accepted by European consumers. However, it is common to get reports of fruit quality problems, mainly due to maturity. Thus, the objective of this study was to develop calibration models for soluble solids content (SSC) and dry matter (DM) of 'Palmer' mangoes using portable (VIS-NIR) spectrometer. Interactance spectra were obtained with a portable F-750 spectrometer in the wavelength range of 306-1140 nm, 8 nm spectrum resolution, and 4 scans averaged per spectra. Spectra were used to develop SSC and DM models using partial least square regression (PLSR) with full cross validation. The best SSC calibration model was developed using spectra pre-processed with standard normal variate (SNV), first derivative of Savitzky-Golay and window of 699-999 nm. It was observed a RMSE CV of 1.39%, with a R CV 2 of 0.87, and RPD of 2.77. Better results were observed for the DM calibration model which was built with raw spectra using the window of 699-981 nm (RMSE CV of 8.81 g kg −1 , R CV 2 of 0.84, and RPD of 2.51). Poor calibration models were obtained for firmness. The results indicated that portable VIS-NIR spectrometer can be used as a non-destructive technique to assess SSC and DM content for 'Palmer' mangoes. It is necessary to incorporate more sources of variation, to reduce RMSE values and improve robustness, especially for fruit SSC and DM prediction.

Cold storage of ‘Palmer’ mangoes sorted based on dry matter content using portable near infrared (VIS-NIR) spectrometer

“…Prior to the cold storage, 20 fruit were harvest (132 DAB) and VIS‐NIR spectra were collected according to the methodology described by Subedi et al () and Santos Neto et al () using a portable F‐750 (Felix Instruments, Washington), on the wavelength range of 310 to 1,100 nm, using interactance as optic configuration and a resolution of 8–13 nm. The light source was a halogen lamp.…”

“…The dry matter (DM) content was determined as reported by Santos Neto et al () and the PLS model described by these authors was used to predict the maturity stages based on DM content. The VIS‐NIR spectra of the prior harvest (132 DAB) were incorporated into the data set and a new PLS model was developed using full crossvalidation on the spectral range of 699–981 nm without applying any preprocessing according to Santos Neto et al ().…”

“…VIS‐NIR spectra obtained in the first harvest (132 DAB) was used as a prediction set applying the DM calibration model developed by Santos Neto et al (). The Unscrambler version 10.3 (Camo, Oslo, Norway) was used for data analysis and the prediction performance was evaluated according to the coefficient of determination ( R 2 ) and the root mean square error of prediction (RMSE P ) as stated by Golic and Walsh (), and Nicolaï et al ().…”

“…Marques, Freitas, Pimentel, and Pasquini () studying ‘Tommy Atkins’ mangoes used a portable MicroNIR 1700 to predict SSC, DM, TA, and firmness with low root mean square error of prediction (RMSEP), 0.92°Brix, 0.51%, 0.17%, and 12.2 N, respectively. Santos Neto, Assis, Casagrande, Cunha Júnior, and Teixeira () reported the use of a portable F‐750 to predict DM in ‘Palmer’ mango with good results, root mean square error of crossvalidation (RMSE CV ) of 8.3 g.kg −1 and RMSE cv of 8.8 g.kg −1 with a of 0.86 and of 0.84. Nordey, Joas, Davrieux, Chillet, and Léchaudel () reported that ‘Cogshal’ mango quality varies with preharvest and postharvest practices, and the differences in SSC, DM, hue angle, TA, and firmness were determined using a portable LABSPEC 2500 NIR spectrometer.…”

“…Therefore, as it is essential to develop standard maturity indices for mangoes for a particular cultivar, growing region, and for local or export markets (Yahia, ), and the importance of an accurate maturity stage determination prior cold storage, the objective of this study was to use the calibration models for DM content prediction of ‘Palmer’ mango developed by Santos Neto et al () to sort mangoes prior cold storage and to evaluate the physiological and chemical changes during the storage period of 14 days similar to maritime shipment from Brazil to Europe.…”