FRUIT RIPENESS DETERMINATION BY ELECTRONIC SENSING OF AROMATIC VOLATILES

A sniffer for determining fruit ripeness nondestructively, based on el ectronic sensing of gas emissions, was developed. The sensing head con sists of a semiconductor gas sensor located within a small cup that is placed on the fruit surface, in this study, for a period of up to 30 seconds. Natural gases emitted by the ripening fruit accumulate in the cup and cause a change in the sensor's conductivity. The sensor was t ested an three muskmelon cultivars over two growing seasons. The overa ll Bayesian maximum likelihood classification accuracy was 90.2% when separating unripe from ripe fruit (two-way classification), and 83.0% for sorting into three ripeness categories (unripe, half-ripe, and rip e). Comparison of sniffer performance with traditional methods of ripe ness determination, including flesh firmness, stem detachment force, p ercent soluble solids, and ethylene emissions, demonstrated that perfo rmance of the electronic sniffer had a higher degree of accuracy than all other destructive and nondestructive methods evaluated Classificat ion accuracy of fruit growing in the field under ambient conditions we re comparable to fruit measured in the laboratory: 88.0% and 78.3% for two-way and three-way classification, respectively.