Winegrowers Supplies  -  Making Red Wine

Making red wine is an 'art', making white wine is a 'science'.

There are many variations in the process of making red wine, for example:-
- de-stemming or leaving the stalks in (providing they are 'woody').
- a 5 day pre-fermentation maceration before a shorter hot fermentation.
- a longer slower fermentation at controlled/lowered temperature.
- 'pumping over' or 'automatic treading' or using a roto-fermenter, or simply using a wood baton, to regularly push the skin cap below the fermenting must/wine.
- not pressing for 3 weeks after the end of fermentation, and during this time pumping over several times a day to maximise extraction of colour, tannin and flavour from the skins.
- etc.
  It all depends on the grape variety, and the condition and ripeness of the berries, that's why it is an art.

Fermentation takes place 'on the skins', so Botrytis-infected grapes need to be removed where possible during picking, before de-stemming/crushing. A small percentage (2 %) is acceptable. Top producers do this selection/removal on a rolling table on the way to the de-stemmer.

1) De-stem/crush: into an open top variable-capacity tank:

    De-stemming is essential with English grapes, to avoid flavours from the unripe stalks.

    Measure the volume of mash in the holding tank. Then estimate the final volume of wine after pressing; this will be on average 83 % of the volume of the mash; I find this varies from about 80 % to 86 % according to grape variety and size of berries:-

Forecasting the %-extraction (% of must/juice that will eventually be pressed out from the de-stemmed mash) is not easy and relies on experience. Each variety and vintage year is slightly different, according to the juiciness of the particular grapes. In my vineyard with the varieties Pinot Noir, Rondo, Regent, Dornfelder and Dunkelfelder, the overall average has been 83.3%, but individual wines have varied from 77 % (small dry berries) to 89 % (large juicy berries):-
  Pinot Noir (thin skins): from 82 % to 89 %, average 84.5 %
  Rondo is the most consistent: from 81.5 % to 84.5 %, average 83 %
  Regent/Dunkelfelder: from 77 % to 86.5 %, average 82.5 %
  Dornfelder: from 80 % to 89 %, average 83.5 %

   Immediately after de-stalking/crushing: to stop any 'browning', add wine sulphur at
2.5 to 6 grams per 100 litres of mash. Wine sulphur takes out some colour so add as little as necessary.

a) Measure the acidity of the must with a test such as the Sulfacor. The measurement gives the 'tartaric equivalent' acidity.

   If acidity is above 8 g/l then de-acidify with Neoanticid down to 8 g/l; de-acidification procedure.
    For red wine the aim is 5.00 to 5.75 g/l in the finished wine; 1.5 to 2 g/l can be lost in primary fermentation, 1.5 to 2 can be lost in malo-lactic fermentation; the higher the acidity initially the greater the loss (11 g/l drops to 7 g/l).
   It is important to de-acidify immediately as most of the red colour is lost from the de-acidified juice; so de-acidify before much colour out comes from the skins.

b) Measure the specific gravity (°Oechsle) of the clear must, with a must refractometer (or must hydrometer and trial jar).

    Calculate the predicted 'natural' alcohol of the must. Add granulated sugar to increase 'total' alcohol to 12.0 %vol; enrichment procedure.

    Add the calculated amount of sugar progressively (day by day) during the fermentation; add at the time the 'skin cap' is being pushed down.

c) Add 'red wine' pectolytic enzymes: 10 ml of Trenolin Rouge DF per 100 litres of mash.

    Add yeast nutrients; should be added before the addition of the yeast.

d) Rehydrate the selected yeast; rehydration procedure.
    Add to the must, stir and leave to ferment.

    American-oak toasted-chips can be put in the tank at this stage, use 2 grams per litre. The chips should be in a muslin sheet, tied to form a sack, with a stainless steel weight to hold them below the surface, and secured with a long nylon cord, so they can be pulled out easily from the top of a variable-capacity tank.
During fermentation is the best time to add this but it can be added later and left in for many months afterwards to give extra complexity to the wine.

    The skin-cap rises considerably during fermentation, to allow for this a large gap must be left at the top of the tank. At least once a day the skin-cap must be pushed down under the must, with a small tank this can be done with a wood-baton. For large tanks there are various possibilities such as roto-fermentors or an 'automatic treading' system. The traditional method of 'pumping over' is less good as the grapes are not macerated.

2) Press: after 7 (up to 9) days skin-contact:

    The press juice has more colour, tannin and flavour than the free-run juice.

    Measure the volume of must, compare against the estimated amount.

3) Racking: after the fermentation/settling is complete (typically 30 days after pressing):

    Early racking means that the wine has less herbaceous/plum aroma 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.

    Pump into the bottom inlet of the receiving tank (clean and sterile).
Aeration which occurs when racking is not a disadvantage (as is the case with white wine), in fact regular racking develops the character of the wine more quickly.

    When first racking, add the calculated amount of wine sulphur: initially 3 to 7.5 grams per 100 litres of wine; giving about 30 to 75 mgm/litre total SO2, according to whether you hope malo-lactic fermentation will take place or not.
    For malo-lactic fermentation to take place the total SO2 must be less than 50 mgm/litre, although it can take place at higher levels.
    Put the calculated amount of wine sulphur into the receiving tank before pumping. This is better for the wine than rousing it in afterwards.

4) Malo-lactic fermentation:

    For malo-lactic fermentation to start, the temperature of the wine needs to be at least 15 °C. In late Spring, once the temperature rises sufficiently, a malo-lactic fermentation usually starts. The optimum temperature is 18 to 20 °C.
    Malo-lactic fermentation consumes at least 50 % of all SO2. After the malo-lactic fermentation is complete (it takes a few months) the total SO2 should be measured and increased to 50 to 75 mgm/litre. Remember that the total SO2 level at bottling should be 50 to 75 mgm/litre (I suggest maximum 100 mgm/litre).
     After malo-lactic fermentation is complete the bacteria settle out slowly, so don't rack too early.

5) Barrique maturation:

     Keeping red wine in barrique (225 litre oak barrel), for 6 months or longer, has a great benefit on maturation and mellowing of red wine.
     Care is needed to ensure that air is excluded from the barrel, as wine kept in a fairly warm place and in contact with air/oxygen, will become vinegar; the alcohol being turned into acetic acid.

6) Fining/filtration:

    Using pectolytic enzymes will normally ensure that eventually the wine becomes clear, if not then fining can be carried out.

    To make the wine more 'supple' and delay later precipitation of colloidal colouring matter: use 5 egg whites (not the yolks) per 225 litres of wine, 
gently stir into a little cold water (125 ml per egg white) until cloudy, then add a little salt until the mixture becomes clear. If it foams/froths remove and dispose of the froth, then add the mixture to the wine with the rouser already running (it needs to be distributed very quickly), rouse for at least 10 seconds. Then leave for at least 2 weeks to settle.

    Rough filtration is a possible alternative to fining, but has a different effect.

7) Bottling: once sufficiently matured:

    Sterilise the bottles with 2% free SO2 solution, some hours prior to filling, I find this adds about 5 to 8 mg/litre free SO2 to the wine. So either the bottles should be rinsed with pure water or this should be allowed for in the SO2 calculation.

    Measure and adjust the total SO2 level so that it is 50 to 75 mgm/litre; well below the upper limit set by European Commission regulations.

    Rack off from any sediment, putting any wine sulphur needed in the receiving tank. Leave to settle overnight then bottle directly from the new tank.