Nondestructive detection of brown core in the Chinese pear ‘Yali’ by transmission visible–NIR spectroscopy

Brown core is an internal disorder sometimes seen in pears under controlled atmosphere (CA) storage. The symptoms are not externally recognizable and visible only after cutting the fruit. Development of nondestructive measurements of brown core of pears would benefit producers, processors, and packers. A technique using body transmittance in the 651–1282 nm region was evaluated as a nondestructive technique for identifying the Chinese pear ‘Yali’ with brown core. Based on the 651–1282 nm region, discriminant analysis with Mahalanobis Distance (MD) analysis can discriminate between brown core and normal pears and grade the brown core pears to three classes—slight, moderate, and severe. None of the good pears was misclassified as brown core, and none of pears with brown core was misclassified as normal pears. Exhaustive searches of the best combination of individual chrematistic wavelengths were performed on a set of 66 pears from two categories–good and brown core. The best modeling classification occurred for precisely aligned pears using the difference at two wavelengths, 713 and 743 nm. When optical density (OD) difference between 713 and 743 nm was applied to a test set, the classification model correctly identified the good or brown core with 95.4% accuracy. Only 5.3% of the good pears were incorrectly classified, 4.3% error of pear with brown core were classified as good fruit.