Racking is the term used to describe decanting, or removing wines from deposits that gradually build up during fermentation. These deposits are made up of minute particles of fruit (or vegetable where roots are employed) and dead yeast cells.
During the early stages of fermentation a great deal of new yeast is made and a great deal of unwanted fruit pulp with this yeast settles to the bottom of the vessel. A little of both, however, are kept in suspension by the agitation caused by the upsurge of carbon dioxide bubbles. The heavier solids forming the lees at this stage are too heavy to be kept in suspension.
Lying at the bottom, the fruit particles and yeast cells are subject to autolysis after a time. This is caused by what we might call ‘further enzyme action’. (We have seen under the section on fermentation that enzymes play an important part in this process.)
It is at this stage, when much of the yeast is dead and when there is a deposit of particles of vegetable matter, that further enzyme action causes decomposition of both. And as you know anything decomposing is likely to give off smells. In the case of wines this decomposing matter is undoubtedly the cause of the development of what we call ‘off flavours. Difficult as these are to describe, you can detect them at once when you taste the wine. To avoid this unpleasant occurrence, periodic racking is desirable. But unnecessary disturbance should be avoided — by this, I mean racking every few weeks or so. This is quite unnecessary. Wine-makers with a good deal of experience will know almost instinctively when to rack and when to leave alone.
In the normal way, a method of making wines will include racking in the early stages of production in its scope of operations. For example, ten or fourteen days after yeast is added to the must and fermentation begun, the must is put into jars and the deposit left in the fermenting vessels. This is the first racking. Thereafter the wine is allowed to carry on fermenting under fermentation locks, and new deposits build up.
The need to remove this second deposit is not so urgent simply because, when the first racking rook place, almost all vegetable matter was removed and a much smaller yeast colony was left to carry on the ferment. And this is why fermentation is far slower than during the early stages.
In the normal way, further racking should not be carried out for eight to ten weeks, unless a heavier-than-average deposit is building up. Normally, the yeast is not coloured by the fruit being used. So if you find that you have a deposit building up quickly and that this is coloured, it means that you have a good deal of fruit particles in the deposit. So do not delay removal of these longer than is necessary.
Racking in this fashion assists clarification. But racking should not be mistakenly used as a means of clarifying. Bear in mind that wines will not clear while there is still fermentation going on. Admittedly, I have had wines as brilliantly clear as they will ever become with occasional gas bubbles rising lazily to the surface. But there will always be exceptions to the rule, as experienced wine-makers will know.
As fermentation slows down over a period of time, the deposit likely to build up will be slight indeed. The initial racking will rid the must of the more troublesome deposits, and the second racking will take care of any remaining deposits that may cause trouble. Thereafter the build-up should be very slight and this need not be cause for alarm.
Whether or not to rack to remove this fine deposit when the wine is put away to finish clearing at the cessation of fermentation depends to a great extent on the clarity of the wine. If the wine is near-brilliant, there should be no need to rack at this stage because it will only be a matter of weeks (or even days) before the last of the minute solids in suspension have finally settled out. Then, and only then, should the wine be racked into storage jars, free from all deposit. This operation should be done by siphoning.
If however, there are 5 mm or so (¼ in) of deposit and the wine is still cloudy when fermentation has ceased, it would be wise to rack before putting the wine away to clear. This is advisable in case the wine takes longer than usual to become brilliant, in which event the wine would be left on the deposit longer than is desirable.
When brilliant wine is put away for storing, it is generally thought that no more deposits will.form. Unfortunately, this is not the case, very often — indeed, more often than riot — wines will throw deposits even though they were brilliant to the eye when put away. When the wine is in stone jars or barrels it is impossible to tell whether further deposits have occurred because we cannot see through these as we can see through glass.
It is therefore a good plan when storing wines in stone jars or barrels to fill a bottle with the wine to be stored and cork and seal it as if it were the finished product. Label it so that you know which bulk lot it belongs to and then, after three or four months, examine the bottom of the bottle carefully. If there are deposits there, however slight, there will be slightly heavier deposits in the bulk lot. This will be evidence of the need to rack.
Sometimes, with very dark glass bottles, it is difficult to detect whether there is a deposit or not. If this problem arises, hold the wine up to the bright light and twist the bottle sharply. If a deposit is present, it will rise up into the wine like a cloud of smoke. This will settle in an hour or so.
Sweet wines, it must be understood, are often slower to clear than others, especially the very sweet ones. This is because the sugar present is in more or less the form of syrup and this, naturally, tends to slow down the settling out of the almost weightless solids.
You will appreciate that after each racking there is certain to be a little less wine. It is therefore advisable to put the wine into smaller containers each time, even if this means using 2 ½ ltr (½ gall) jars rather than larger vessels. This will mean that the advantages of bulk storing are lost. But the alternative is to store the wine with a large air-space above it. Since this air-space can lead to bacterial infection I know which alternative I prefer. Hence my recommendations in my other works and magazine articles (where I gave recipes for making 3ltr (1 gall) lots) to put half in a 2 ½ ltr (½ gall) jar and bottle the remainder. This almost inevitable ending to my magazine recipes is a bit of a stock joke among the knowledgeable wine-makers. But they do agree that it is better than storing with a large air-space above the wine.
Many wine-makers anxious to store in bulk for as long as possible prefer to make more than 5ltr (1 gall), say a quarter as much again as is actually required when all the processes have finished. This little extra is kept fermenting separately from the bulk and is used to top it up after each racking. In this way, whether it be 5 or 251 (1 or 5 gall) that they want to set aside for storage, they may do so without having to leave an air-space overhead. This sort of thing is a trick of the trade that people think up for themselves.