New Electronic Nose Sniffs Out Perfectly Ripe Peaches for Harvest

The e-noses can be dispersed across an orchard to ensure each tree is harvested at optimal times

3 min read
Peaches on a tree
Photo: iStockphoto

Have you ever tried to guess the ripeness of a peach by its smell? Farmers with a well-trained nose may be able to detect the unique combination of alcohols, esters, ketones, and aldehydes, but even an expert may struggle to know when the fruit is perfect for the picking. To help with harvesting, 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.

Enose prototype under a peach treeAn early prototype of the e-nose system developed by the Brazilian researchers sits under a peach tree. A new version will integrate all the components into a weatherproof, solar-powered system.Photo: Henike Guilherme Jordan Voss

The system is also equipped with a ventilation mechanism that draws in air from the surrounding environment at a constant rate. The passing air is subjected to a set level of humidity and temperature to ensure consistent measurements. The idea, Stevan says, is to deploy several of these “noses” across an orchard to create a sensing network.

He notes several advantages of this system over existing ripeness-sensing approaches, including that it is online, conducts real-time continuous analyses in an open environment, and does not require direct handling of the fruit. “It is different from the other [approaches] present in the literature, which are generally carried out in the laboratory or warehouses, post-harvest or during storage,” he says. The e-nose system is described in a study published June 4 in IEEE Sensors Journal.

While the study shows that the e-nose system already has a high rate of accuracy at more than 98 percent, the researchers are continuing to work on its components, focusing in particular on improving the tool’s flow analysis. They have filed for a patent and are exploring the prospect of commercialization.

For those who prefer their fruits and grains in drinkable form, there is additional good news. Stevan says in the past his team has developed a similar e-nose for beer, to analyze both alcohol content and aromas. Now they are working on an e-nose for wine, as well as a variety of other fruits.

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Europe Expands Virtual Borders To Thwart Migrants

Our investigation reveals that Europe is turning to remote sensing to detect seafaring migrants so African countries can pull them back

14 min read
A photo of a number of people sitting in a inflatable boat on the water with a patrol ship in the background.

Migrants in a dinghy accompanied by a Frontex vessel at the village of Skala Sikaminias, on the Greek island of Lesbos, after crossing the Aegean sea from Turkey, on 28 February 2020.

ASSOCIATED PRESS

It was after midnight in the Maltese search-and-rescue zone of the Mediterranean when a rubber boat originating from Libya carrying dozens of migrants encountered a hulking cargo ship from Madeira and a European military aircraft. The ship’s captain stopped the engines, and the aircraft flashed its lights at the rubber boat. But neither the ship nor the aircraft came to the rescue. Instead, Maltese authorities told the ship’s captain to wait for vessels from Malta to pick up the migrants. By the time those boats arrived, three migrants had drowned trying to swim to the idle ship.

The private, Malta-based vessels picked up the survivors, steamed about 237 kilometers south, and handed over the migrants to authorities in Libya, which was and is in the midst of a civil war, rather than return to Malta, 160 km away. Five more migrants died on the southward journey. By delivering the migrants there, the masters of the Maltese vessels, and perhaps the European rescue authorities involved, may have violated the international law of the sea, which requires ship masters to return people they rescue to a safe port. Instead, migrants returned to Libya over the last decade have reported enslavement, physical abuse, extortion, and murders while they try to cross the Mediterranean.

If it were legal to deliver rescued migrants to Libya, it would be as cheap as sending rescue boats a few extra kilometers south instead of east. But over the last few years, Europe’s maritime military patrols have conducted fewer and fewer sea rescue operations, while adding crewed and uncrewed aerial patrols and investing in remote-sensing technology to create expanded virtual borders to stop migrants before they get near a physical border.

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