Differentiation of deciduous-calyx and persistent-calyx pears using NIR hyperspectral imaging analysis.

Abstract. Korla Fragrant pears are small oval pears characterized by light green skin, crisp texture, and a pleasant aroma after which they are named. The flesh of deciduous-calyx pears is considered more desirable in taste and texture attributes than that of persistent-calyx pears; Chinese packaging standards require that each packed case of highly demanded “superior” class pears contain 5% or less of the persistent-calyx fruits. Near-infrared hyperspectral imaging was investigated as a potential method for automatic sorting of the two types of pears. The hyperspectral images were analyzed, and wavebands at 1190 nm and 1199 nm were selected for differentiating deciduous-calyx fruits from persistent-calyx fruits. A multispectral differentiation algorithm using the ratio of the pears’ relative intensities at 1190 nm and 1199 nm was developed. The results showed that the algorithm correctly classified 89.3% to 94.0% of deciduous-calyx pears and effectively differentiated pears such that the number of persistent-calyx pears misclassified as deciduous-calyx pears comprised only 2.4% to 4.9% of all pears classified as deciduous-calyx pears, performing well within the targeted packaging standards.