pp wrote:

> On Mar 23, 1:00 pm, "Paul E. Lehmann"
> > wrote:
>>
>> > Jim
>>
>> In my opinion, the yeast does not contribute
>> directly to the flavours. Each strain has its
>> temperature range, pH range and acidity that it
>> will perform best and thus possibly allow
>> flavours ALREADY PRESENT IN THE FRUIT to come
>> out
>> or be suppressed. This is my personal opinion
>> and I am sure there are those who will disagree
>> with me.
>>
>> I have never done the following but I think it
>> would lend some insight:
>>
>> Make a water sugar solution to about 22 brix
>> and bring it up to a pH of say 3.5 - no fruit
>> or
>> flavouring and ferment with different yeast.
>> My bet is that you will not get that
>> "Blackberry", "Plum" or whatever descriptor you
>> choose to use. I know that the yeast
>> manufactures make all kinds of claims that
>> their yeast will add such and such flaovours
>> but I ain't buying it.
>>
>> Some have claimed to use different yeast on a
>> divided lot of the same fruit and fermented and
>> could tell a difference. Again, there may be a
>> difference but I doubt the Yeast produced the
>> flavours. Different strains merely allowed the
>> flavours already present in the fruit to come
>> out.
>>
>> Also, I have seen differences in the exact same
>> fruit with divided lots in different fermentors
>> or carboys and the exact same treatment and
>> yeast
>> used. This is just one of the mysteries of
>> Organic Chemistry.
>>
>
> My understanding is they're not saying that the
> yeast produces all
> those flavours and aromas on its own, rather
> that the yeast acts as a catalyst that
> emphasizes certain characteristics. In that view
> it's not black or white, i.e, the environmental
> characteristics like pH, temperature, etc. of
> course contribute to how the yeast performs but
> that doesn't preclude the yeast from making its
> imprint on the must.
>
> I'm not very good in picking up subtle
> differences between batches done with different
> yeasts, but I've had one very clear case where
> the result went along the lines of what the
> yeast company said - we used D21 and D254 on
> Petite Sirah and the D21 batch had noticeably
> more acidity in the end, not by measurement but
> on the palate. This was still obvious after 1
> year of aging.

I agree that certain strains will metabolize
different acids differently. There is one strain
- I forget which one - that can gobble up Malic
acid. Unfortunately, I used it once in an Apple
wine and Voila - a very flabby wine. I should go
back a say that in addition to pH, temperature,
acidity - the type of acid in the fruit may or
should have a bearing on the yeast strain to use
- or not use, in my case.

> Over the years, I've come up with some yeast
> favourites for different wine styles, and the
> selections were originally based mostly on the
> purported style effects of the yeast, with the
> environmental factors like temperature range
> just as a rough preselection step. So even if
> some or most of the marketing blurbs were just
> hype, I'm happy with the practical results.
>
> Pp

If you are happy with certain yeast then I say by
all means go with it or them. You are probably
fermenting under roughly the same conditions
every year and what works for you works.

I wonder if anyone out there has fermented a red
wine with something like D-47 at a temperature
around 50 degrees.

My guess is that it would be very light and fruity
compared to something like the same must using
Pasteur Red and fermented at 85 degrees.

Now, did that fruity wine with hints of berries,
cherries etc. etc. result from the yeast or the
fact that the D-47 does quite well at lower
temperatures, completes fermention in reasonable
time and the Pasteur Red does not.

By the time the wine with the Pasteur Red
completed fermentation at the cooler temperature
(if it ever would go to completion), the wine
would have been on the skins for longer than the
normal time and I am sure there would be taste
differences due to that fact alone.

With all that said, I am more than willing to
experiment with different yeast, and I probably
will.