A zero Matter Other than Grapes (MOG) rating at the winery is the gold standard all growers and winemakers strive for. But is it possible with existing mechanised harvesting processes?
Recent trials – run by Aussie Wine Group (AWG) in conjunction with Wine Australia – suggest that it is.
AWG has been extensively trialling its grape sorting system – which removes MOG at the point of harvest – across Australian and US wine regions over the past three years.
So how does it work?
The MOG Removal Unit is a stand-alone system that can be deployed on harvest bin trailers/gondolas, or retrospectively installed onto the boom arm of harvesters. The sorting unit removes MOG directly from a grape harvester prior to catching in a bin/gondola in the field. This system allows only fruit to fall into the bin or gondola and the separated MOG falls onto the ground in the vineyard.
The unit can be adapted to any harvesting system, including as a standard trailing sorter (mounted to a bin or gondola); boom mounted sorter (mounted to a discharge arm); in-harvester high capacity sorter (designed to fit inside a harvester, with vine shakers); and a high capacity trailing sorter mounted to a bin/gondola and designed for high tonne areas.
The trial of six MOG removal units captured metrics from harvesting equipment and crew.
The units consistently delivered fruit picks with a MOG percentage of 0.2 per cent. The Australian wine sector standard rates MOG on a scale of 0–5, where a zero rating is applied to completely clear fruit, while a MOG rating of three or more is rejectable by the winery. A MOG percentage of less than 1 per cent equates to a zero MOG rating, which is most desired by many wine makers.
At the winery, where possible, two crushes were undertaken alongside each other – one processing fruit harvested without the MOG removal unit and the other with the MOG removal unit. The fruit was then sent to different presses and fermenters for wine production.
“This allowed us to evaluate the outcomes of the wine quality in the very early stages of production via small batch fermentation trials. Wine makers then have an opportunity to evaluate and produce different wines from the two different treatments,” said Matt Sciancalepore, the Director of AWG.
Key findings from the trial included:
- Operators of the system reported that the infield sorters were easy to set up and operate, and were reliable.
- Wineries were able to reduce their throughput time by up to 40 per cent as a result of receiving zero MOG samples from the sorters.
- In one comparison, grapes only had a 30-minute exposure to MOG. This lack of exposure had a positive impact on colour and flavours of the wine.
“Our trials have shown that infield grape sorting is now an affordable option for growers, allowing MOG ratings to be improved and giving growers the opportunity to negotiate better prices for their clean fruit,” said Matt.
“It also minimises grape juice loss when the harvester is set correctly to work in conjunction with the sorting system.”
The technology in action
Gemtree Wines vineyard manager, Troy Elliker, has been using the MOG Removal Unit technology for three years and last season managed to achieve a zero MOG rating.
“With a few tweaks along the way we’ve managed to get our MOG rating down to 0.2 per cent consistently over all varieties,” Troy said.
Lake Breeze Wines vineyard manager, Tim Follett, has been using the high-volume sorting unit on his harvester.
“The AWG Infield Sorter has allowed us to deliver zero MOG to our winery consistently, with more full berries and no juice loss from our harvester regardless of the vineyard we harvest,” Tim said.