I would have thought the the reason for using commercially produced
yeast over naturally produced yeasts is that the results are more
controlled and the alcohol produced of as know type (i.e. ethonol).
Certain types of alcohol are toxic to humans and I believe these types
can be produced by using wild yeasts (In some circumstances).

Allowing wild yeasts to be used in your ferments can produce
unpredictable results leading to stuck ferments, off tastes and
Volitile Acidity problems.

I know of many people who only rely on wild yeasts to ferment however
I have never had the bottle to experiment and waste a once a year
opportunity by taking a chance.

Lets face it, many older italian winemakers produce superb wine one
year and average the next. Isnt it all about being consistent year
after year...?

AB1



(Zack S) wrote in message . com>...
> One issue that has not been brought up is "YEAST FINNING" (All Reds).
> This is a technique used to increase the amount of phenolics donated
> to the wine
> fom yeast. Commercial yeast or wild yeast may be used for the primary
> fermentation, but active yeasts are added to the wine after dryness to
> increase mouthfeel and reduce bitter and astringent flavors. When the
> active and rehydrated yeasts are added they will produce polyphenols
> as the lyse and eventually fall out of the mixture to settle at the
> bottom of the tanks. The wine should be left on these dead yeasts
> until maturity is obtained. This "fining" should take place after an
> appropriate aging period.
> Note: Be careful to monitor any VA as the yeast will become a nutrient
> source for any opportunistic spoilage yeasts or bacteria. One of the
> most predominant American wild yeasts Kloeckera Apiculata also has
> high VA levels, so I also recoment that primary fermentations use
> comercial, low VA yeasts with proper nutrition.
> A good strain for yeast fining is Lalvin D254
>
> > >