A lot depends on where the grapes come from. If the grapes are from an area
where grapes have been grown and wine has been made in the vineyard for many
years, then probably a good wine quality yeast is the dominant yeast growing
on the grapes. If the grapes are from an area new to growing grapes or
where few grapes are grown the other wild yeasts are probably the dominant
yeast growing on the grapes. Adding a good strain of yeast to the must is
just insurance. Insurance is purchased, or not, at the discretion of the
individual. Some people are luckier than others.

Ray

"Richard Sydney" > wrote in message
om...
> My father of italian origin has been making perfect wine for years and
> has not once used yeast. What is the purpose of adding yeast? What
> does it do?
>
> Richard Sulfaro
>