Winegrowers Supplies
- De-acidification of Must
2. Double-salt de-acidification with Erbslöh Neoanticid
Neoanticid is a specially prepared 'chalk' (calcium carbonate) with specific reaction properties which allow the
crystallizing of calcium malatartrate.
Using this method tartaric and malic acids will reduce
in roughly equal parts as a so called double-salt, this
provides a substantially larger scope for de-acidification than by using Kalk.
In double-salt de-acidification the tartaric acid
content also limits the amount of de-acidification, but substantially more
scope for de-acidification is given than by using Kalk.
A special procedure is necessary: for precipitation of the double-salt the pH value in the must/juice has to be kept above 4.5. This is achieved by mixing the calculated weight of Neoanticid with a portion of the must. The portion will in this way be de-acidified totally and, after separation of the resulting crystals, recombined with the portion which has not been de-acidified. After mixing thoroughly the calculated acid content should be reached. The procedure for treatment is described in detail below.
Erbslöh's chart should be used to determine the weight of Neo-anticid (NA) and the Partial Volume (TM), according to the initial acidity and desired final acidity:-
In order to reduce acidity by 1 g/l, 0.67 g/l of Neoanticid is needed.
TV = total volume (litres) of must to be treated.
D = desired de-acidification in g/l = initial acidity (top line of table) -
desired final acidity (vertical scale on left hand side of table).
The figures in the table relate to 1000 litres of must to be treated, and kilograms of Neoanticid.
Required quantity of Neo-anticid (grams) = NA = approx 0.67 x TV x D (as table above).
Partial Volume (litres) of must to be treated = TM = approx TV x D / TA (as table above)
(plus small extra % of TV if press-lees are included).
Maximum de-acidification possible in g/l = [TA x (WA - FWA)]/[TA - WA] where:-
TA = total titratable acidity (expressed as tartaric acid) in g/l
WA = tartaric acid content in g/l (typically 40% x TA)
FWA = final tartaric acidity in g/l (has to be a minimum of 1.0 g/l).
The procedure for treatment:-
1. First it is necessary to rack off (or press out in the case of red wine) the calculated Partial Volume of clear must to be de-acidified.
With white wine it is usual to include the press-lees in the Partial
Volume, in which case a small % should be added to the calculated Partial Volume (to allow for solids that will not be
recovered).
Clear must is first racked into a receiving tank, leaving the Partial
Volume (including press lees) in the initial tank.
2. Mix the required weight of Neoanticid to a paste with a little must and put in a third tank (or a vat), of capacity at least 1.5 times the Partial Volume to be treated.
Then the Partial Volume of must is added very slowly to the Neoanticid paste, mixing it continually. In this way the freely emergent CO2 is driven off so that stable pH conditions (above pH 4.5) are ensured.
3. After the CO2 release has been concluded, complete separation of crystals should be carried out as soon as possible. Usually, if left for 30 minutes the crystals will have settled out sufficiently for a considerable amount of clear must to be racked off, the remainder should then be treated with Trub-ex.
4. As there is very little acid in the de-acidified portion it will oxidise quickly, so the de-acidified portion should be added back to the non-de-acidified must immediately.
If a suitable method of separation (eg. Trub-ex) is not available, then a simplified procedure can be used: the de-acidified portion is mixed back into the non-de-acidified must without the crystals being separated. After the crystals have been deposited the relatively pure must which is left is carefully racked off. However, especially where there are extreme acid values, there is a danger of calcium tartrate back-formation.