Winegrowers Supplies - Yeast Nutrients
Enartis Nutriferm Vit is a combined yeast nutrient: Diammonium phosphate (vitamin A) and Thiamin (vitamin B1).
For treatment of must in general; especially important for grapes affected by botrytis.
It reduces or dispenses with the need for SO2.
Quantity: 30 grams per 100 litres is the highest amount allowed of Nutriferm Vit.
Dissolve the Nutriferm Vit in a little water stirring all the time before adding it to the must. It should be added before the addition of the yeast.
Storage: store the Nutriferm Vit in a cool dry place protected from light. Seal the opened packet well.
Avoiding Hydrogen Sulphide problems by addition of diammonium phosphate:-
from John Danilewicz (Barnsole Vineyard, Canterbury):-
The literature teaches us that a source of this noxious gas is elemental sulphur used in spraying. This can be dealt with by attention to spray interval. However, the real source is the breakdown of sulphur-containing amino acids by yeasts in their quest for nitrogen. This occurs when their preferred amino acids, which do not contain sulphur, are in short supply. The approved way of dealing with this is to add diammonium phosphate (DAP), which we are permitted to do up to 300 mg per litre. Ammonia is readily taken up by yeasts which diverts them from their use of these sulphur-containing amino acids.
For some years now we have regularly added DAP as a precautionary measure up to the permitted level, and have eradicated our hydrogen sulphide problem. As a chemist I know that I am very sensitive to this gas and to the even more unpleasant mercaptans it produces if left in wine. We have also submitted all our wines to the Quality and Regional Wine Schemes for the last seven years, and none of the tasters have ever complained of this fault.
I find that different grape varieties have a different propensity to produce the problem. Madeleine Angevine never seems to, but Schönburger always does. I also
find that low concentrations of hydrogen sulphide can be eliminated by aeration if done early, but if left and mercaptans are formed, the problem becomes much more serious.
from John Walker (Dragons Rock Vineyard):-
I have problems with the perceived wisdom that sulphur sprays are the source of hydrogen sulphide in wine. In one of my previous incarnations I worked for an American megacorp as a research scientist where one of my functions was the development of flavour systems for catfood. Elemental sulphur did not react (i.e. be converted to hydrogen sulphide or thiols or sulphides) below about pH 10 and below about 130 °C for a prolonged time period. I suspect that the metabolism of sulphur-containing amino acids is the route to production of hydrogen sulphide and sulphur compounds in wine. I only use elemental sulphur and sodium bicarbonate sprays on my vines (Siegerrebe) and have never encountered hydrogen sulphide or sulphur compounds in the wine.