Wine Making Yeast is a 

Must

if you Want Wine

I get a lot of emails from people wanting to know about wine making yeast.  Most seem to know that it is required if you want wine, but some do not know that.  Some want to know why wine making yeast is necessary.

Wine making yeast is necessary simply because without it you will have no wine, only grape juice. It is when the grapes meet the yeast that the process of fermentation happens and without that process you will not have alcohol.

Grapes have sugar in them and when the sugar is gobbled up by the one celled living fungi, yeast, then alcohol is made.  Yeast is very small, so small it takes almost 20 billion of them to make up one small gram of yeast.  How amazing is that?  For your chemistry majors out there, the chemical reaction that happens in this process is C6H32O6+yeast=2C2H5OH+ 2CO2.

It was in1859 that Louis Pasteur discovered that a single cell organism was responsible for the conversion of sugars into alcohol and carbon dioxide. The Egyptians were the earliest recorded users of yeasts.

There is much commercially grown wine making yeast that is packaged in small amounts for home wine makers to be able to afford and use.  They make it by using a known strain of yeast and adding it to sugars that help it multiply rapidly.  They then harvest the yeast.  Lately it seems the most popular kind of preserving yeast is to then freeze dry it and keep it in the refrigerator until needed.

To use the yeast then all you have to do is reconstitute or rehydrate it with water at 40C then let it sit for a half hour.  It is then added to the wine must to begin fermentation.  There are many kinds of yeast products, it is important to only use wine making yeast and not try to use say bread making yeast as it just will not work.  

Yeast does occur naturally in the wild and settles on grapes, but they are killed before fermentation.  If left on the grapes and allowed to be part of the wine they would give unpredictable results and some really different and even bad smelling wine.  It is the wine maker that decides what results he wants in his wine even before the fermentation process is started.

So you can see how important it is to wine to have wine making yeast added.   Without it you really do not have wine for the fermentation process would never be allowed to begin.  Choose wisely as the type of wine making yeast you do add can change the flavor of your wine.