The application of FT‐NIRS for the detection of bruises and the prediction of rot susceptibility of ‘Hass’ avocado fruit

Abstract

BACKGROUND A rapid non‐destructive in‐line grading system that can rapidly and accurately assess individual avocado fruit for internal quality attributes, including bruises and rots, would allow the avocado industry to provide a more consistent fruit quality to the consumer, optimise market distribution and ensure maximum yield for the producer and retailer. Fourier transform–near‐infrared (FT‐NIR) spectroscopy was investigated to detect bruises and rot susceptibility as an indication of shelf‐life in avocado fruit at both the sprung stage of ripeness and eating ripe fruit. RESULTS The classification models (principal component linear discriminant analysis, partial least squares discriminant analysis and support vector machine) for each of three growing seasons found hard green fruit that were deliberately bruised could be correctly detected with 70–78% accuracy after 2–5 h following impact damage and with 83–89% accuracy after 24 h. For eating ripe fruit, the accuracy was 60–100% after 2–5 h following impact damage and 66–100% after 24 h. The ability of the classification models to accurately predict rot development into two classes, ≤10% and >10% of flesh affected, ranged from 65% to 84% over the three growing seasons. When the rot classes were defined as ≤30% and >30% the accuracy was 69–77%. CONCLUSIONS The results of the study highlight the potential of FT‐NIR reflectance spectroscopy for application in a commercial, in‐line setting for the non‐destructive evaluation of impact damage and rot susceptibility of whole avocado fruit. The study indicates that fruit should be held for approximately 24 h prior to scanning to allow bruise development to occur, particularly in hard fruit (i.e., stage 2) prior to bruise assessment. © 2018 Society of Chemical Industry