Thursday, October 23, 2008

Fermentation Finale

It has been awhile since I continued with my winemaking journey.  Harvest season is like that.  It takes over your life in the late summer/early fall, and everything else gets put on hold.  It has been a long, drawn out harvest as the weather ended up being a huge factor, with bouts of heavy rain at inconvenient times.  But the wines are coming along nicely and I am expecting this vintage to be quite good in spite of the obstacles.

And so, I will continue now where I left off.  In my last winemaking blog I discussed the use of nutrients in the fermentation, and, in particular, DAP or diammonium phosphate.  At this point of the winemaking process, the juice should be in full fermentation.  As I mentioned before, keeping the fermentation cool will enhance the aroma and fruitiness of a white wine.  I prefer about 60 degrees.

It is a good idea to check the progress of the fermentation about every other day.  This means using your hydrometer again.  Simply put a sample of the fermenting wine into the hydrometer cylinder and float the hydrometer in it, in the same way you measured the sugar in your juice.  As the sugar ferments out, the hydrometer will sink in the liquid – lower each time you test it.  When the level of the wine is below zero (which is actually the reading above the zero on the hydrometer), the wine should be done fermenting.  I always make sure that all of the sugar has fermented out because I don’t want any surprises later while the wine is in storage or, even worse, in the bottle, should it decide to start fermenting again.

The product used for this late stage sugar test is a Clinitest tablet.  This is actually a product created to test for sugar in urine but it works equally well with wine.  Winemaking supply stores carry the starter kits (which consist of a small test tube, dropper, and some tablets) and also the additional tablets when you need them.  It is an extremely easy test.  You simply put two drops of the wine into the small test tube and add 10 drops of water.  Drop the tablet in and let it dissolve.  It reacts immediately and foams up like Alka-Seltzer.  Be careful not to touch the part of the tube with the wine and tablet in it as this is very hot.  Within seconds the foaming dies down and the liquid has turned to a particular color.  If it is blue, there is no sugar left.  If it is blue-green up through green or mustard color, there is still sugar in the wine.  There is a chart included with the kit where you can compare the endpoint color in your tube and see what percent of sugar remains. If you still have some sugar to ferment out, give it another couple days and test it again.

Next:  Can I drink it yet?

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