To help with the harvesting of various fruits, scientists have been developing electronic noses for sniffing out the ripest and most succulent peaches. In a recent study, one such e-nose exceeds 98 percent accuracy.
Sergio Luiz Stevan Jr. and colleagues at Federal University of Technology - Paraná and State University of Ponta Grossa, in Brazil, developed the new e-nose system. Stevan notes that even within a single, large orchard, fruit on one tree may ripen at different times than fruit on another tree, thanks to microclimates of varying ventilation, rain, soil, and other factors. Farmers can inspect the fruit and make their best guess at the prime time to harvest, but risk losing money if they choose incorrectly.
Fortunately, peaches emit vaporous molecules, called volatile organic compounds, or VOCs. “We know that volatile organic compounds vary in quantity and type, depending on the different phases of fruit growth,” explains Stevan. “Thus, the electronic noses are an [option], since they allow the online monitoring of the VOCs generated by the culture.”
The researchers say their e-nose has several advantages over existing ripeness-sensing approaches, including that it conducts real-time analyses in an open environment and does not require direct handling of the fruit.
The e-nose system created by his team has a set of gas sensors sensitive to particular VOCs. The measurements are digitized and pre-processed in a microcontroller. Next, a pattern recognition algorithm is used to classify each unique combination of VOC molecules associated with three stages of peach ripening (immature, ripe, over-ripe). The data is stored internally on an SD memory card and transmitted via Bluetooth or USB to a computer for analysis.