Comparison of Instrumental Non-destructive and Destructive Firmness and Color Measurements with Human Inspection in Clingstone Peaches

Abstract

The flesh color and flesh firmness of over 13,000 clingstone peaches were measured instrumentally in 2004 and compared to the current official manual inspection methods of the California Department of Food and Agriculture. The instruments evaluated were an impact-type non-destructive firmness instrument, a universal testing instrument equipped with a Magnus-Taylor style penetrometer and a LED-based colorimeter. The instrumented measures gave good agreement (83% across all clingstone cultivars) with the current inspection method in categorizing fruit into acceptable, immature, and bruised, overripe or soft categories. The level of agreement varied by cultivar, with agreement for some cultivars improving if individual classification models were developed for those cultivars. The results confirm that flesh color is not a good predictor of flesh firmness and that destructive quasi-static firmness measures are not good predictors of high velocity impactstyle firmness measurements. The results also show that there is a need for standardization of impact-style firmness measurements.