Wine Flavors from Fermentation - Part 2


So far, we've learned that wine gets it flavor from three things - the grapes, fermentation and aging. Last time we looked at the fermentation process and how the yeast can affect flavor. But before we move on to flavors associated with aging, let's take a step back to the first item that affects a wine's flavor - the grapes.

While the juice of the grape plays a leading role in the flavors of a wine, the other parts of a grape also can play a supporting role. Items such as the stems from the bunch of grapes, the grape skins and the seeds.

These grape solids are all potential modifiers of the finished wine's flavor. These grape solids contain tannins, proteins and other microscopic solids that can benefit the final product. But, other solids such as leaves, sticks from the grape vine and dirt are undesirable solids that are always removed (For reference, these undesirable items are often referred to as MOG: Materials Other than Grapes.)

With respect to the stems that the grapes were grown on, winemakers can decide if they want to de-stem the grapes before the wine making process begins.  White wines are usually made from de-stemmed grapes. But, a red wine’s tannin is increased by leaving some or all of the stems in the juice.

Grape skins also contain flavor compounds. And, just like brewing a cup of tea, the longer you leave the grape skins in contact with the juice, the bolder the flavors can become. The depth of color of a wine also comes from the length of time the wine is left in contact with the skins.  For example, if you remove the skins immediately, no color is imparted to the wine.  The best example of this is Champagne, a sparkling white wine, that is produced from Chardonnay grapes (a white wine grape), and Pinot Noir grapes and Pinot Meunier grapes that are both red wine grapes. Another example is rosé wines that are made from red wine grapes that see very little skin contact time after pressing resulting in the light pink color.

The grape seeds will also play a role in the wine's flavor as it ferments because they too contain tannin that adds structure and makes wines better able to be aged.

So, it's not just the juice from the grape that affect the flavor of the wine. These other solids play a very important role.

Next time we'll take a look at the final process that affects a wine's flavor, the aging process.

Until then, Cheers!


Wine Flavors From Fermentation

Yeast on Grapes.jpg

Wine's flavors come from the grapes, the fermentation process, and through aging. Last time we looked at the grapes that are the primary player in a wine's flavor. So, let's now explore how the fermentation process adds flavors to wine.

The only other ingredient in wine making, other than the grapes, is the yeast.  And, yes, yeast adds flavor. Just think of freshly baked bread.  Not that yeast makes wine taste like bread, but it certainly can impart flavor. Wine can be made from the natural yeast that forms on the skin of the grape, appearing as a white haze, as shown in the photo.  Or, winemakers can choose to use one of many strains of yeast that are produced in the laboratory in order to achieve the end result they are looking for.

The fermentation vessel also plays a role in a wine's flavor. Fermentation that is done in stainless steel tanks impart no flavor and allows the fruit flavors of the grapes to shine through. But, when fermentation is done in oak vessels the wine can take on woody flavors as well as flavors of spices, vanilla, and smokiness, as well as tannin that gives wine its mouth-drying, astringent, sensation.

Once fermentation is complete and the yeast has given its life for the production of alcohol, the yeast can either be immediately removed or the dead yeast (called lees) can be left in the fermentation vessel for some additional time to add yet additional flavor. This often adds a bit of bread-like aroma to the wine and makes for a richer mouth-feel of the final wine. Battonnage, or the stirring of the lees in the wine, can also enhance these flavors.

The fermentation process can also result in wines that are a bit sweet. Typically, the yeast will consume all the grape's natural sugar, turning it all to alcohol. But, if the fermentation is halted before all the natural sugar is consumed by the yeast, the wine will retain 'residual sugar' and be a bit sweet.

Oh, and by the way, the grapes, not just grape juice, can also play a role during fermentation. But, we'll leave that for next time. Until then, Cheers!



How Lees & Battonage Are Used in Wine Making

A couple of weeks ago, I reviewed a Sauvignon Blanc from Chile. The tech sheet that came with it described how the wine was made including the terms 'maceration,' 'lees,' and 'battonage.'  We took a brief look at 'maceration' last time where, simply put, it is a term for allowing the grape skins, seeds and stems to soak in the juice (the must) either prior to fermentation or during fermentation.

After the yeast does its job during fermentation by 'eating' the natural sugar in the must and transforming it to alcohol, fermentation is complete and the yeast dies. These dead yeast cells that remain in the wine, along with bits of grape seeds and solids, are called 'lees.'

At this point, the lees can either be removed from the wine (by racking or fining methods) or they may remain in the wine. If they are left in the wine, they will break down and release compounds that interact with the fermented wine. This interaction can create additional complexity, aroma and flavor.

But, with time, the lees tend to settle at the bottom of the aging vessel. If the lees are just left in the bottom of the aging vessel, they can clump up and actually become detrimental. So, if a wine maker wants to age their wine 'on lees,' they need to periodically stir the wine to keep the lees mixed in with the aging wine. Battonage (or Bâtonnage) is this periodic stirring of the wine. Battonage essentially helps redistribute all these positive lees compounds into the wine, making sure all the wine comes in contact with them.

The term battonage derives from the stirring stick, a baton.  The baton is placed in the top opening of a barrel (bung hole) and gentle rotated within the barrel to stir the wine and re-distribute the lees during aging.

So, there you have it. Many wine makers use maceration, lees and battonage in their wine making process. A bit technical, yet important parts of making all the great wines we enjoy. Cheers!


What Does the Word 'Maceration' Mean in Wine Making?

The words 'maceration,' 'lees,' and 'battonage' are somewhat technical wine words. My recent review of a Sauvignon Blanc from Chile included these terms that were included on the spec sheet. While the words themselves may be unfamiliar, their meanings are actually quite simple.

After the grapes are picked, the juice is extracted from the grapes to create the wine. At this point, the grape skins, seeds and stems can either be immediately separated from the juice or they can be left in contact with the juice.

Maceration occurs when the grape skins and solids are intentionally left to soak with the extracted juice.

There is 'cold' maceration (40-50° F) that takes place before fermentation and 'warm' maceration (70-90° F) that is done while the wine is fermenting. This warm maceration process, used primarily in making red wine, allows the alcohol being produced in the fermentation process to act as a solvent to extract color, tannins and aroma from the skins.

Maceration times vary, depending on the type of wine being produced. Red wines typically have extended maceration time (7-40 days) while Rosé wines get very brief maceration (2-24 hours). Maceration is not typically used in the production of white wine, but when done, it may only last for 12 to 14 hours.

Next time we'll look at the other terms 'lees' and 'battonage' used in the wine making process. Cheers!


What is Residual Sugar in Wine?

One of the terms that gets thrown around in the wine world is 'Residual Sugar.' But it's not something you are going to read about on a wine's label. So, what is it and why should you care?

Let's take a quick step back and review the basics of the wine making process. Simply put, grapes are grown, picked, crushed and fermented into wine then aged and bottled. It's the fermentation process where sugar comes in. 

Grapes naturally contain various types of sugar. Glucose and Fructose are the two most common sugars, but there are others. Grapes also contain varying levels of sugar. Grapes that are allowed to fully ripen, in warm climates, will contain more sugar than grapes that struggle to ripen in cooler climates. And, wine makers will closely monitor the sugar levels (Brix) in grapes while still on the vine, and choose to pick their grapes when the sugar levels are 'just right' for the grape-type they are growing and their style of wine making.

During the fermentation process, yeast is added to the sugary grape juice. The yeast feeds on the sugar and produces alcohol. If there is any sugar remaining after fermentation, it is referred to as 'residual sugar' (usually noted as RS) and is typically recorded in grams per liter (g/L). This is somewhat of a technical term for a wines' resulting sweetness.

Residual sugar is one component that can contribute to a wine tasting sweet. Next time we'll further explore sweetness in wines.  Until then, Cheers!