nitrogen deficient must

Hey,
this is my first posting, so be gentle. At work I get alot of questions about why "some wines give people headaches, or make them sick", and not due to over consumption. Most people blame it on the sulfites....In my reading, I found some info, about the fermentation process.
As the yeast breaks down the sugars, it needs nitrogen in the must to survive. If the must is deficient of nitrogen, it begins to break down the ammino acids to get to it's nitrogen. The alcohol that is produced from the ammino acid nitrogen is toxic to the human body and it stays longer in our system. Creating "hangover" like symptons.
I realize it would be impossible to prove, but is it that simple, that a nitrogen deficient must, is the reason why some wines give people unexplained reactions to wine.
jenniferr

That's the general idea, but not quite right.

The yeast normally gets nitrogen from the grapes (yup - amino acids) not the air, but some grapes are deficient in nitrogen.

In those cases the fermentation may 'hang' or get stuck, and you can also get hydrogen sulphides (stinky) when the fermentation starves for nitrogen.

Because adding nitrogen containing compounds to the must may result in other unwanted byproducts, many prefer selecting a yeast strain that requires less nitrogen.

I'll try to remember to ask the local school of winemaking at the university here if there have been any advances on that reading - it has probably been 5 years since I bothered looking at the subject.

Oh yes - and welcome to the group, Jennifer.

Welcome Jennifer. Good group of Canadians here so feel at home!

Hi Jennifer -

I'm not sure this is what you meant, but the chemist in me can't let me go without replying that the alcohol is the same compound regardless of the nitrogen levels in the must. My understanding is that there's some evidence that histamines found in red wine (in particular) can cause headaches for some people. I don't know if histamine levels are higher in wines made with nitrogen-deficient must or not, though.

Syrah grapes are, I believe, often low in nitrogen, resulting in the sulphide and stuck fermentation issues that Bill mentioned. Many winemakers will add yeast nutrient to the must to keep the little critters happy and producing the desirable components rather than the nasty ones.

Anyway, welcome to the board!

Mike

Hi Jennifer -

I'm not sure this is what you meant, but the chemist in me can't let me go without replying that the alcohol is the same compound regardless of the nitrogen levels in the must.

The chemist in me read it as meaning the difference between methanol and ethanol, both of which are alcohols if not "alcohol." Regarding the question of the source of red wine headaches, see what I wrote here.

Mark Lipton

Jennifer,

It most certainly is NOT the sulfites. Sulfite allergy causes asthmatic-type breathing problems (tightness in the chest, shortness of breath, asphyxiation in very severe cases), not headaches.

Some people (my father, for instance) are sensitive to the anthcyanins that occur in red wine. He can't drink any red wine without getting migraines. Blue cheese (the blue color is from anthocyanins in the mold) also trigger this. Of course, his favorite combination was Port and Stilton. He now has to be content with white wine.

-Paul W.

Hi Jennifer -

I'm not sure this is what you meant, but the chemist in me can't let me go without replying that the alcohol is the same compound regardless of the nitrogen levels in the must.

The chemist in me read it as meaning the difference between methanol and ethanol, both of which are alcohols if not "alcohol." Regarding the question of the source of red wine headaches, see what I wrote here.

Mark Lipton

Good point - I hadn't thought of other alcohols.

I feel like I have a hundred more questions. Ultimately, you're saying there are so many variables it is impossible to name one cause.
Thanks
Jennifer

Bob,
Thanks, I feel out of my league, especially since my wine options here in Nova Scotia, are limited. Although we've come a long way in our selections for wine.
jennifer