Spinning cone
Spinning cone columns are used in a form of steam distillation to gently extract volatile chemicals from liquid foodstuffs while minimising the effect on the taste of the product. For instance, the columns can be used to remove some of the alcohol from wine, 'off' smells from cream, and to capture aroma compounds that would otherwise be lost in coffee processing.
Mechanism
The columns are made of stainless steel. Conical vanes are attached alternately to the wall of the column and to a central rotating shaft. The product is poured in at the top under vacuum, and steam is pumped into the column from below.[1] The vanes provide a large surface area over which volatile compounds can evaporate into the steam, and the rotation ensures a thin layer of the product is constantly moved over the moving cone. It typically takes 20 seconds for the liquid to move through the column, and industrial columns might process 16-160 litres per minute. The temperature and pressure can be adjusted depending on the compounds targeted.
Wine controversy
Improvements in viticulture and warmer vintages have led to increasing levels of sugar in wine grapes, which have translated to higher levels of alcohol - which can reach over 15% ABV in Zinfandels from California. Some producers feel that this unbalances their wine, and use spinning cones to reduce the alcohol by 1-2 percentage points. In this case the wine is passed through the column once to distil out the most volatile aroma compounds which are then put to one side whilst the wine goes through the column a second time at higher temperature to extract some of the alcohol. The aroma compounds are then mixed back into the wine. However some producers such as Joel Peterson of Ravenswood argue that technological 'fixes' such as spinning cones remove a sense of terroir from the wine; if the wine has the tannins and other components to balance 15% alcohol, Peterson argues that it should be accepted on its own terms.[2]
The use of spinning cones, and other technologies such as reverse osmosis, is banned in the EU, although they can be used in wines imported into the EU.[3] In November 2007, the Wine Standards Branch (WSB) of the UK's Food Standards Agency banned the sale of a wine called Sovio,[3] made from Spanish grapes that would normally produce wines of 14% ABV.[4] Sovio runs 40-50% of the wine over spinning cones to reduce the alcohol content to 8%, which means that under EU law it cannot be sold as wine as it is below 8.5%; above that it would be banned because spinning cones cannot be used in EU winemaking.[4]
See also
Notes and references
Further reading
- Robinson, Jancis (2006). The Oxford Companion to Wine, third edition. Oxford University Press. ISBN 978-0198609902.
External links
- FT Technologies (formerly Flavourtech), a column manufacturer, has some good information and diagrams of how the columns work.
- ConeTech, Inc is a large manufacturer of spinning cone columns.
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