Every yeast has a different nutrient/nitrogen requirement. Prisse de
Mouse's requirements are low. Is that what you use?

Dick Heckman wrote:
Now I'm getting worried. I've been making fruit wines for 30 yrs on an
off and on basis and never had H2S or a stuck fermentation without ever
using any nutrients. Is this a grape specific problem? I may have
enough grapes for some wine this year.

Dick

AxisOfBeagles wrote:
It is possible to have a lab test for YAN (yeast assimilable nitrogen)
... but that is costly and time consuming, not something most home
winemakers do. Quite a few commercial wineries don't do it either.

I err on the side of caution. I add DAP (diammonium phosphate) and
nutrients at the outset of fermentation. There are numerous sources on
how much to add; I use apx. 20 to 40 g of DAP per 10 gallons of must,
and 20 g of superfood per 10 gallons of must. If I'm dealing with grapes
that have previously been prone to H2S, or if I suspect low nitrogen
(growing conditions), Imight add more DAP.




On 2008-05-22 06:50:30 -0700, Wayne Harris said:

I to this point, i have used Cabernet concentrate to make my batches.

I have had the most success when I add yeast nutrients to the
concentrate.

In reading Lum Eisenman's "THE HOME WINEMAKERS MANUAL" Chapter 12, he
states:

"Stuck fermentations can be due to a lack of nitrogen, the lack of an
essential yeast nutrient, the use of damaged yeast, excessively low or
high fermentation temperatures, etc. Whatever the causes, prompt
action is needed, and the stuck fermentation should be restarted as
quickly as possible. "

This fall, when i get my load of real grapes, how will I be able to
detect the lack of nitrogen, or lack of yeast nutrient?

Or do i simply add appropriate amounts of both to the must?

I really don't want to screw this up.