Wednesday, October 24, 2012

Refrigeration in the Wine Industry

No, not getting the bottle of white wine cold before drinking but keeping the juice (must) and wine cool during the production process ie. grape delivery, crushing, fermentation, pressing, transfer, storage.
Modern wineries use refrigeration units to keep their white fermenting musts cool.
This encourages desirable aroma and flavour compounds. The target is usually between 10°C and 16°C.
The temperature of grapes coming in from the vineyard during harvest in summer can be a lot higher than this, so cooling is almost always necessary.
But what about the more primitive 'Vin de Garage' operations like mine?
How do I keep the ferment cool without going to a huge (and unwarranted) equipment expenditure?
Adding dry ice has been suggested. This would have the additional advantage of adding carbon dioxide as an oxidizing protectant but it always involve the danger of taste taint and it is not the safest thing to handle (burns and asphyxiation).
Putting a small tank inside a larger one and filling the void with an ice or ice/salt mix has been suggested together with insulating the outside tank with a flexible foam sleeve. Logistically all possible but no real temperature control.
Adding ice in containers to the actual must is another suggestion. This could be viable as long as the containers were sanitized and secure so any melt water did not get into the wine.
Searching on the net I found plenty of information on the affects of ice addition to water and the resultant cooling affect.
One formula was able to calculate final temperature based on original weight and temperature of water and weight of ice added.

I decided to test this out. So I added a specific amount of ice (1000g) contained in a sealed mineral water bottle to a specified amount of water (6000g) and noted the temperature drop. It fell 6°C in one hour and remained there for about 3 hours before starting to rise.
The result was considerably higher than the formula predicted . I guess ambient conditions were to blame.
However this method is indeed worth pursuing and I will try a full scale experiment with water in a wine tank soon.
Temperature could be adjusted by the addition and removal of bottles. Maintenance of the required temperature would depend on the number of bottles required. That is the great unknown at this stage.

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