What is wine fermentation?

In short, it is the complex action whereby the living organism of yeast breaks the sugar down into carbon dioxide and alcohol. The action of the yeast on the sugar continues until the volume of alcohol has reached somewhere between 12.5% to 14%.

At this stage, the yeast organism is destroyed by the alcohol it has produced and fermentation ceases. This is what is known as a natural wine. Most commercial products come under this category until they have been fortified. This period of fermenting in the tub can be a dangerous time. Because of this, the fermentation process should be completed as soon as possible (even at the risk of losing a little of the wine's bouquet).

Next, we must then keep the brew warm. Our goal here is to bring about ideal conditions in which the living organism and yeast cells can multiply more rapidly. Warmth helps to ensure this. The faster they multiply, the more rapidly they convert the sugar into alcohol and therefore, the sooner the yeast destroys itself.

Do not be tempted to keep a brew hot during fermentation. During warm weather, any odd spot will do for a fermenting brew. Also, a warm spot in the kitchen or in an airing cupboard is as good as any during the winter.

After 14 day of fermentation in a warm place, the wine can be bottled or put into stone jars. This is the time to add the isinglass.

Adding the Isinglass:

Isinglass is not needed to clarify flower or fruit wines made with the recipes given at www.e-homewinemaking.com. These wines will clarify themselves quite readily within a few weeks of fermentation. Nor is isinglass an absolute need for clearing root wines. However, I have found that root wines and wines made from a mixture of roots and fruits, do clear more readily with the help of isinglass. For this reason, some recipes will instruct you to "proceed with isinglass and bottling".

When put into wine, isinglass forms an insoluble cloud which surrounds the minute solids in the wine and gradually forces them to the bottom of the bottle.

Besides assisting the clearing process, isinglass helps to solidify the lees, thereby rendering them less easy to disturb while moving the bottles or when wine is poured from a bottle containing lees.

There are many methods of using isinglass, but the one I use myself without fail results is as follows:

Take one quart of the wine and warm it very slowly in a saucepan. Next, crumble 1/8 of an ounce of isinglass over the surface of this wine and then stir with a fork until everything is dissolved. Then pour it into the rest of the wine in a circular motion.

Many people advise dissolving the isinglass in a small amount of water. As we've seen, ordinary tap-water quite often contains wild yeast; the very act, then, of using water might well ruin all of our efforts to keep wild yeast out of the wine.

When purchased from a chemist in 1/2 ounce or 1 ounce quantities, the amount required is easy to calculate, and this is usually plenty for one gallon of wine.

When the isinglass has been added, put the wine into sterilized bottles or jars and cover as already directed. The wine must then be returned to a warm place, and kept there until all fermentation has ceased.

If the wine were put in a cold place the yeast might go dormant and the wine would not be able to ferment. If it were later moved into a warm room, or the weather happened to turn very warm, the yeast would become active and start fermenting again. In a warm place, fermentation will not fail.

If you happen to notice that the top half-inch of wine has become crystal-clear, seal the bottles at once! This is a clear indication that fermentation has stopped. Unfortunately, we rarely get this invaluable guide.

When all fermentation has stopped and when no more small bubbles are rising to the top, the yeast is dead. Fermentation cannot begin again unless wild yeast or bacteria get into the wine and start that souring ferment that I've previously mentioned. Perfect air-tight sealing at the earliest possible stage of production is critical.

Push the cork down hard and seal with sealing-wax. If screw-top bottles are available, use these if you prefer. Personally, I never use any other kind when I can find them. Remember that the yeast is dead, so fermentation cannot begin again and explode the bottles or blow the corks unless wild yeast or bacteria reach the wine. Screw-top bottles are, then, the obvious choice.

About the Author

James Wilson owns & operates www.e-homewinemaking.com, a site providing wine-making tips, tricks and techniques. If you're interested in making your own wine, visit www.e-homewinemaking.com today and sign up for the FREE wine-making mini-course!

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Wine Fermentation


What is wine fermentation?
In short, it is the complex action whereby the living organism of yeast breaks the sugar down into carbon dioxide and alcoh...


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