Wine grapes may soon be joining oranges and strawberries, on the list of "Fruits That Are Now Inspected and Sorted by Machines." As part of the Grapesort project, Germany’s Fraunhofer Institute for Optronics, System Technologies and Image Exploitation has helped create an automated system that not only gives bum grapes the boot, but also divides up the good ones according to quality.
The process begins with a vat of grapes being delivered straight from the vineyard, and going into a feeding unit. That unit guides them into a destemming machine manufactured by project partner Armbruster Kelterei-Technologie. As its name implies, that machine pulls the stems off the grapes.
From there, the now-stemless grapes are individually (and gently) placed on a conveyor belt, which carries them past a sorting module at a speed of three meters (9.8 ft) per second. Using an integrated high-speed camera, that module snaps and analyzes photos of 18,000 grapes per second. Among other things, it looks for foreign objects such as twigs, leaves or bug bits, along with grapes that are moldy, damaged or otherwise no good. Using an air ejection unit, all of those things are blown off the conveyor belt for disposal.
The sorting module also analyzes the shape and color of the non-rejected grapes, to determine their ripeness and quality grade. They can then be divided into grade groups, for use in different types of wine. In the future, it is hoped that the module will also be able to determine ripeness by measuring the grapes’ sugar content, based on an analysis of the manner in which they reflect light.
So far, Trollinger, Riesling, Weißburgunder and Lemberger grapes have been successfully sorted using components of the system. A complete prototype is set to go into use in a pilot project in October, with a tasting of the resulting wine planned for next June.
Geisenheim University and beverage tech company Ingenieurbüro Waidelich are also collaborating on the project.