Winegrowers Supplies - Making White Wine - without skin contact
1) Destem/crush - directly into the press.
Press, pumping the must/juice into a holding tank.
Measure the volume of must in the holding tank.
Add 'white wine' pectolytic enzymes (to improve clearing etc): 3ml to 5ml per 100 litres of must.
Add 10 grams of wine sulphur
per 100 litres of must, to try to 'sterilise' the must and ensure that malo-lactic
fermentation does not take place later. This SO2 is consumed during the fermentation process.
More experienced winemakers use much less wine sulphur, unless the grapes are in poor condition (or the temperature is high): add 4 to 8 grams per 100 litres of mash; pectolytic enzymes reduce the need for wine sulphur.
Rouse and leave for 12 - 24 hrs to settle.
Prepare bentonite; to remove excess protein.
2) Next day:
a) Measure the acidity of the clear must (from the top of the holding tank) with a test such as the Sulfacor.
If necessary de-acidify with Neoanticid
(de-acidification procedure) down to:
Madeleine Angevine: 9 g/l
Schönburger, Phoenix, Bacchus, Huxelrebe (flavoursome soft varieties): 9.5 g/l
Orion, Kernling and other wines intended to be 'medium-dry': 10 g/l
Riesling, Chardonnay, also wines intended to be 'medium': 10.5 g/l
Senator and other wines intended to be 'medium-sweet': 11.5 g/l
If no de-acidification is necessary then simply rack off the clear must into a clean tank, then use Trub-ex to clarify the cloudy must remaining in the bottom of the holding tank, adding this clarified must to the rest of the clear must.
b) Measure the specific gravity (°Oechsle) of the clear must, with a refractometer (or must hydrometer and trial jar).
Calculate the predicted 'natural' alcohol of the must. Add granulated sugar to increase 'total' alcohol to the desired level for the type of wine - see enrichment procedure.
c) Add the bentonite suspension, after draining off excess water.
Bentonite is not added before this, since it inactivates pectolytic enzymes.
d) Add yeast nutrients; should be added before the addition of the yeast.
e) Rehydrate the selected yeast; rehydration procedure.
Add to the must, stir and leave to ferment.
3) Soon after the fermentation is complete: lower the lid of the variable-capacity tank so that it floats on the wine. Or add Nitrogen or CO2 to the top of a fixed-capacity tank.
4) Racking: at about 4 to 6 weeks after the end of fermentation; settling is complete.
Early racking means that the wine has less flavour from the yeast-lees.
Normally racking is carried out through the flap-valve. If a tank is without a man-way door it is possible to rack off through the bottom outlet of the tank, although this is not normal practice; if the yeast-lees are compact enough only a small amount of lees is carried through. The first litre or so can be run off into a large jug or bucket, the juice from this can then be poured into the receiving tank leaving the solid sediment to be discarded.
To minimise the aeration which occurs
when racking; make sure there is no leak on the suction side of the pump. The
colder the temperature the more oxygen the wine can dissolve (leading eventually to greater oxidation).
Each racking will reduce the ultimate quality of the wine, so plan to rack only the minimum number of times necessary (once only if possible).
Pump into the bottom inlet of the receiving tank (clean and sterile); if using a variable capacity tank put the floating lid inside (with pneumatic seal deflated, and any cooling plates removed) so that it rides up with the wine.
Before starting to pump, put into the receiving tank a calculated amount of wine sulphur; 8 to 10 grams per 100 litres of wine; i.e. sufficient to give about 40 to 50 mgm/litre free SO2, which will help to prevent oxidation of the wine, until the free SO2 level falls below about 20 mgm/litre (depending on the pH of the wine).
5) Every month or two: take a sample of the wine and measure the level of free SO2, with a test such as the Sulfacor.
Add wine sulphur to raise the free SO2 to 35 mgm/litre.
Some grape varieties (eg. Pinot Gris, Senator, Phoenix) 'consume' free SO2 more quickly than others so need more frequent sampling and addition.
6) Sterile Filter and Bottle:
From mid-April onwards, once sufficient time has gone by and low enough temperatures have achieved tartrate stability (excess tartrate has precipitated on the walls of the tank).
The wine will need rousing (for some hours) to remove excess CO2, unless you like spritzig/petillant wines.
Test for protein stability.
Sterilise the bottles with 2% free SO2 solution, some hours prior to filling, I find this adds about 5 to 8 mg/l free SO2 to the wine. So either the bottles should be rinsed with pure water afterwards or this should be allowed for in the SO2 calculation.
To make off dry wines: add Süss-reserve,
carry out tastings at 0.5% intervals to ascertain the optimum % addition.
Add the desired amount and rouse in well.
Re-test for protein stability.
Measure and adjust the free SO2
level so that it is 30 to 35 mgm/litre (slightly more if it is a sweet wine).
Measure the total SO2, this must be below the upper limit set by European Commission regulations.
Filter and bottle.