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Oz winemakers attempt to find the sweet spot

Published:  23 July, 2008

By Tom Cannavan
On a recent trip to McLaren Vale, a new winemaking technique was on everyone's lips: sweet spotting'.

The sunny and hot climatic conditions of South Australia mean that sugars in grapes ripen before phenolic ripeness of skins, stems and pips. The latter comes only with sufficient hang time, but that means ever-increasing sugar and higher alcohol.

Sweet spotting assesses numerous samples of a wine, where the alcohol has been lowered in small steps. A natural 15.5% ABV wine might be lowered to 13.0% ABV, but samples at each intermediate 0.1% increment are also created. This produces a line-up of 26 samples on the winemaker's bench, each one with fractionally lower alcohol. The samples are tasted in an attempt to find the 'sweet spot': the point of optimum aroma, flavour and balance.

There are basically two parts to the physical process of lowering the alcohol to hit the sweet spot: the first uses a membrane to separate 'permeate' (alcohol and water) from other components of the wine (colour, aroma and flavour), then the second breaks down this permeate into its components so that some alcohol can be removed. The de-alcoholised permeate is then back-blended to create the finished wine.

While reverse osmosis and spinning cone machines can already do this job, a new Australian technology from the Memstar company is the force behind the rush to sweet spotting. Memstar completes the whole alcohol adjustment process in a sealed unit, at low temperature. Results are said to be impressive, with negligible loss of aroma and flavour.

One winemaker from a large McLaren Vale operation told me: 'We conduct this process so we can deliver the best quality to the consumer. In higher alcohol wines, the fruit is masked, appearing dull. By finding the sweet spot, the fruit is more generous and better balanced. High-alcohol wines also become hot and dry once primary fruit falls away, so the process is valid for wines destined to be cellared.'

There is also a tax break for wines with less than 14% ABV exported to the US, but the McLaren Vale producers really do seem to be sweet spotting on purely quality considerations. Given the evidence of global warming, could this be the holy grail for winemakers concerned about rising alcohol levels?