Dry matter (DM) has recently been proposed as a new quality index for apple, inspiring similar investigations in other tree fruit crops. Near-infrared spectroscopy (NIR) enables the nondestructive estimation of DM and other quality attributes, although the accuracy and reliability of this technology on North American pear varieties remain untested. In this study, predictive NIR regression models were developed for nondestructive determination of postharvest DM and soluble solids content (SSC) in d’Anjou and Bartlett pears (Pyrus communis L.) using a commercially available NIR spectrometer. At calibration, models performed reliably with coefficients of determination (R2) of 0.940 (DM) and 0.908 (SSC) for model trained on d’Anjou pears and 0.860 (DM) and 0.839 (SSC) for model trained on Bartlett pears. Application of the models to independent validation datasets demonstrated acceptable performance with R2 values ranging from 0.722–0.901 and 0.651–0.844 between measured and predicted DM and SSC values, respectively. Differences in performance can be attributed to the different DM and SSC values and maturity levels between the fruit used for model calibration and those in the validation datasets. Although not all models developed in this study were accurate enough for quantitative determinations, NIR devices may be useful for orchard management decisions and fruit sorting purposes.
This research was supported by the Northwest Pear Bureau (NWPB) funds, award #PR16-105.
We would like to thank Bob Gix and Blue Star Growers (Cashmere, WA) for orchard access, and Felix Instruments (Camas, WA) for user support and assistance. We also thank Angela Knerl, Ryan Sheick, Stefan Roeder, and Rachel Leisso for their technical contributions.
Authors’ contributions: A.G., S.S., and S.M. substantially contributed to the conception, design of the work, to the acquisition, analysis, or interpretation of data for the work; to drafting the work or revising it critically for important intellectual content; to final approval of the version to be published. All authors are in agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
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