When to do the first racking?

A common question from beginning winemakers is, “When do I do my first racking?”

This is an excellent question, but unfortunately, there is no single correct answer that covers all wines in all situations, which makes things confusing. Kit wine instructions often say, “rack after X days”, as do older recipes. Other recipes call for placing a balloon on the mouth of the fermentation jug, and when the balloon deflates the fermentation is done. Neither is a good choice.

In this post I explain reasons why wine should be racked at certain points, providing information for each winemaker to make their own decision. First, background information:

Why can’t I use the calendar?

The simple answer is that every fermentation is different.

How are batches different? In many ways, which may include the amount of sugar, the amount of nutrient available to the yeast, the type of yeast, if the correct amount of yeast was added initially, if the must was sulfited, the temperature, and if the temperature is constant. Each of these affect how quickly the yeast multiplies and how quickly it eats the available sugar.

Even when all factors appear the same, a single batch fermented in two containers can exhibit different fermentation rates in each container. I’m not going into detail here regarding how these factors affect fermentation — each is a lengthy blog post in itself, and I cannot speak intelligibly to explain all. At least for now, accept the idea that fermentation rate has many factors.

The bottom line is there is no guarantee that a batch of wine will complete fermentation in a set number of days. Sure, the wine can be left for weeks, which greatly increases the likelihood that fermentation will complete. But leaving the wine exposed to air after fermentation opens it to oxidation, which ruins the wine.

At best, the calendar is a very inaccurate method of gauging the end of fermentation.

Why can’t I use a balloon?

A balloon stretched over the mouth of a fermentation jug inflates as the yeast emits CO2 as a byproduct of it eating sugar. When fermentation stops, the balloon deflates as the CO2 leaks out between the balloon and the jug.

Yes, this indicates when fermentation stops. It does not indicate fermentation is complete.

Fermentation can stop for many reasons, especially including large fluctuations in temperature. In this case, the yeast stops eating even when there is more sugar to eat. Various factors can cause the fermentation to restart, e.g., the wine is warmed up. If the wine has been bottled, the renewed fermentation produces pressure and can blow the corks out of the bottles. If the wine is sealed in screwcap bottles, the pressure has no way to vent and if the limits of the glass are exceeded, the bottle can explode.

Neither a balloon nor a calendar can conclusively indicate fermentation is complete, e.g., the yeast has no sugar left to eat.

Why should I use a hydrometer?

A hydrometer is an instrument that measures the specific gravity of a liquid. In winemaking, this measures the amount of sugar in the must (mixture of fruit pulp and/or juice before the first racking).

A hydrometer tells the wine maker many things:

  • How much sugar was originally in the must, which enables calculating the amount of Alcohol By Volume (ABV). [The SG must be checked before fermentation begins.]
  • How close the wine is to completing fermentation.
  • If the wine has completed fermentation

Used correctly, a hydrometer provides accurate information regarding where the must is in the fermentation process. It eliminates guessing and enables the winemaker to make informed decisions.

Fermentation Cycle

For most wines, the original specific gravity, abbreviated as “OG”, is typically between 1.075 and 1.100. A lower OG produces a wine with an Alcohol By Volume (ABV) of less than 10%. This is not usually desired as low alcohol wines have a shorter shelf life. A higher OG is not normally desired as the must is dense, and the yeast may not grow well in an environment with too much sugar. [Reasons for OG outside of this range is outside the scope of this document.]

Fermentation should be started in an open food grade bucket or similar container, typically with a towel laid across the top to keep “stuff” out while letting air in. Yeast needs oxygen to reproduce, so it’s important at the beginning of fermentation that yeast have access to air. Fermentation in a closed container will be slower and may be stunted.

Initially the yeast reproduces, growing a larger colony, which begins eating sugar and emitting CO2 and alcohol. As the amount of sugar reduces and the amount of alcohol goes up. The hydrometer indicates where the fermentation is in the process, e.g., if the OG was 1.090 and the current SG is 1.045, fermentation is roughly half done.

Under normal circumstances, the final specific gravity (abbreviated FG) is in the range of 0.990 and 0.996. At this point all fermentable sugar has been eaten by the yeast and fermentation is done.

At a point near or at the end of fermentation, the first racking is made and the wine is moved to a closed container under airlock or similar mechanism to protect the wine from air.

When To Rack?

As stated above, “when to rack” is not a question with a single answer. This can be affected by circumstances and by needs. Note: when reading the following, consider that this is based upon my experiences, and includes information from winemakers whose opinions I trust.

SG above 1.020 — few winemakers rack when the SG is above 1.020. Among other reasons, moving the wine to a sealed container slows down the completion of fermentation as it is cut off from oxygen, which yeast uses for reproduction. Also, for wine fermented with fruit pulp, separating the wine from the pulp prevents more aroma and flavor from being extracted from the pulp.

I have racked above 1.020 based upon need. My job at that time required travel, and I was going to be out of town when fermentation completed. To protect the wine, I racked earlier than I wanted.

SG 1.010 and 1.020 — some winemakers rack when the SG is in this range to promote and protect aroma. This is commonly done with white and fruit wines.

SG between 1.010 and “done” — this is the range in which most winemakers perform their first racking.

When I rack depends upon the type of wine. For white grape juice and kits without skin packs, I rack when the wine is between 1.000 and 1.010. The exact point varies depending on my available time. I like to have active fermentation when I rack — the wine goes into carboys with a relatively large head space, as the fermenting wine is actively producing CO2. This protects the wine from oxygen as the CO2 pushes air out of the carboy.

Normally I leave the wine in the carboy for 1 to 2 weeks without checking SG. When fermentation completes, the gross lees drops faster and I do not perform the second racking until the lees compact, to reduce wine loss. Once I see the lees compacting, I check SG.

Fruit wines with pulp I rack (actually press, but am using “rack” to simplify the discussion) when the SG is closer to 1.000, to let the wine have longer contact with the pulp.

For red grapes, I press when the SG is in the range of 0.997 to 0.999 to give the wine the longest contact with the pulp.

As with white wines, the wine goes into carboys with large relatively head spaces. At this point the process is identical, regardless of wine type.

Done — a common practice is to rack when fermentation is done. The wine can be racked immediately, or in the case of red wines, the wine may be left for a period of days or weeks to let the wine have more contact with the pulp.

How do I decide?

For a beginner? Keep things simple and rack between 1.010 and “done”. Don’t over think the situation.

For more advanced winemakers? Re-read this article, look at other articles regarding racking/pressing, and make your best decision. Remember that what you do with the next batch of wine doesn’t lock you in. Experimenting with different techniques is good, although researching ahead of time is better.