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Winemaking 101

Like most good things in life, wine was discovered by mistake because grape juice has a natural inclination to become wine. The problem is that wine, in turn, is predisposed to become vinegar, so intervention (winemaking) is required. Here’s how we get from the grape to the bottle to make fine wine.


Harvest at GoosecrossMost winemakers would agree that the harvest decision is the single-most important decision they make in the whole year. Anyone who has grown tomatoes in the back yard know how it goes. The tomatoes start out tart and green and gradually become soft and sweet as long as the weather is warm. It’s same thing with grapes. As long as the weather is good, the sugar increases, the acid decreases and the flavors progress from tart and vegetative to fruity and ripe. Harvest time varies with the region, variety and weather patterns. Here in Napa Valley, early-ripening varieties, such as Sauvignon Blanc, are often ready to pick in late August or early September. For those who produce several varieties, the harvest may take six to eight weeks, or even longer, with late-ripening Cabernet Sauvignon ready for harvest in October and many other varieties harvested in the meantime. The hotter the weather, the faster the harvest.

Grapes on their way to the crushpadThat sequence of events, and flavor maturity in particular, is uppermost in the winemaker’s mind as harvest approaches. From experience, he knows that a little over half the sugar will convert to alcohol in the finished wine and that the level will influence the style. Alcohol gives the wine body, which is important for the reds and full-bodied whites, but it can also give the wine heat when it’s too high. Most wine grapes (excluding sparkling and late-harvest wine) are picked between 21 and 26% sugar and within that rather-large range, flavor maturity and stylistic goals will help make the decision. It’s also important to be sure the acid (generally between 4 and 10 grams per liter) and pH (between the low and high 3s) are in balance for the sake of flavor and stability.

Most fine wine is hand-picked, but the exceptions increase annually (we pick by hand at Goosecross). Hand-harvested grapes arrive as clusters and machine-harvested ones as individual berries, some of which have juiced. We sort through the grapes to remove leaves or grapes that don’t look good. In our warm, dry climate we’re lucky that the clusters come in looking remarkably clean most years. The most common rejects are dehydrated grapes. A rainy year could find us sorting out grapes or clusters that have rotted.


Red Winemaking Process

Crushing and Fermentation

The important thing to know about wine grapes is that, with very few exceptions, the flesh of the grape is colorless regardless of variety. Red wines are dyed red by the skins, which makes the dark varieties the most versatile. Depending upon the length of time the juice is in contact with the skins we can produce red, white or rosé wine from any dark variety.

Cabernet grapes being crushedAfter the grapes are sorted, they’re fed into a machine called a crusher-stemmer, which removes the stems and gently breaks the grape skins open to release the juice. There are options along the way, for instance the winemaker might choose to do a little whole-cluster fermentation for extra meatiness or whole-berry fermentation to heighten fruitiness, but crushing and stemming is standard procedure.

Once the broken grapes are transferred to the fermentation tank, the winemaker can add yeast (most producers) or let nature take its course (less common), since yeast is part of our environment, like bacteria. The added yeast spends a day or two getting acclimated, starts reproducing itself and then begins to feed on the sugar. As it does, the sugar is converted into heat, carbon-dioxide gas and, of course, the alcohol is the most important by-product of the fermentation.

Besides color, the grape skins are the source of most of the flavor, texture and tannin in the wine. A bit of heat helps with extraction, so most winemakers ferment their reds a bit warm. Our winemaker ferments his reds in the mid-70s F. which helps to extract flavor without picking up excess tannin along the way. Some wineries ferment their reds as warm as up to 90 degrees. It’s a question of the effect the winemaker is looking for.

The term “cap management” refers to the so-called cap of grape skins that rises to the top of the tank during fermentation. To aid in temperature uniformity and flavor extraction the winemaker needs to mix the cap back in to the fermenting juice a few times a day. For large tanks, or if he wishes to aerate the wine, the winemaker pumps the wine from the bottom of the tank up, over the top. Or, the winemaker may decide to do a “punch-down”, in which an instrument that looks like a giant potato masher is used to submerge the cap back into the wine manually. This can only be done on relatively small batches.

“Cold soak” or “extended maceration” are techniques meant to enhance flavor extraction. Cold soak refers to pre-fermentation skin contact (to extract fewer seed tannins) and extended maceration is post fermentation skin contact (the tannins polymerize). They both have advantages and disadvantages – it’s a matter of taste and responding to the characteristics of the fruit.

The warm temperature makes the yeast work quickly and the fermentation may be complete inside of a week. For dry wine, the fermentation ends naturally when the yeast runs out of sugar. To make sweet wine, which is rare for red-table wines, there are a couple of methods. The wine can be chilled to the point that the yeast stops working before all of the sugar is used up. In that case the wine should be kept cold and later micron-filtered to ensure that all the yeast cells are removed before bottling. Of course, this technique produces less alcohol. If the winemaker wants both the sweetness and the alcohol he ferment the wine to dryness and add back some grape juice (it’s illegal to add sugar in California) to sweeten the wine up.


When the fermentation has ended, or the winemaker has the desired extraction from the skins, it’s time to press. He drains the wine out of the tank and is left with a big pile of skins and seeds at the bottom. A lucky cellar worker will start by raking out most of the skins and seeds, which we call pomace, and then finish by crawling into the tank to shovel out the rest (these days, some fermentation tanks have bottom gates).

Geoff operating pressThe skins are saturated with good wine, and are loaded into the press. Gravity, alone, will draw some of the wine out, but when the draining slows down it’s time to add pressure. There are many different styles of presses for a winemaker to choose from, but you can think of the process as loading the skins and seeds into a large strainer and squeezing the liquid away from the solids by pushing down on them. A quality producer will use a gentle press and operate it with care. The winemaker can taste out of the press to help decide how much is enough. In any case, the wine that is squeezed out of the skins is different from the wine that drained out of the tank. Most quality producers will keep the press wine separate from the drain wine, which is called free run, and take a look at blending the two later on. Some wineries boast about using only free run, but it’s a question of style rather than quality. A little good-quality press can lend the red wine some extra muscle or structure.

Malo-lactic fermentation is something that’s usually discussed in the context of white wine making, but it’s standard operating procedure for red wine for the sake of stability. The newly-made wine is inoculated with bacteria to catalyze a secondary fermentation in order to prevent it from occurring spontaneously later on. More on this below.

Barrel Aging (click here for information on barrel building)

The wine can be transferred to barrels before or after the malolactic fermentation is complete and, in the world of fine wine, it’s a rare red that doesn’t benefit from some aging. The evolution of the wine inside the barrel is of even greater significance than the contribution of oak flavor.

Geoff in barrel cellarAt press time the reds often look rather purple and feel clumsy on the palate. The slow oxidation that takes place in the porous wood concentrates the wine slightly, matures the color and helps to soften and integrate the aroma and flavor. The length of the stay depends upon the style of wine and should be determined by tasting. Lighter reds tend to mature more quickly than the darkly-pigmented ones.

Aging may sound passive, but it’s labor intensive to manage the wine 60 gallons at a time and to make sure that it remains healthy along the way. A slow, controlled oxidation causes maturation and anything more can lead to spoilage, so it’s important to keep a close eye on how the wine is developing and to send samples to the lab for analysis from time to time.

Aging is a good time to clarify what is, initially, very hazy wine. Gravity can do a lot of the work. The winemaker lets the solids settle and moves the wine off of them periodically, which is called racking. There are more proactive methods such as filtering the wine. The winemaker nearly always uses more than one technique, such as racking first and filtering later, and has numerous other options. The best method(s) of clarification is a topic that can raise a very lively debate among producers.

Blending can take place at any time, and much of it is done as the wine ages. Blending takes many forms, for instance the winemaker can blend different varieties together, or different vineyard locations for the same variety. He can blend barrel-fermented wine together with tank fermented wine, as our winemaker does with our Chardonnay. He can blend wine that’s aged in new barrels with wine that’s been aged in older, less flavorful barrels. The possibilities are nearly infinite and blending is perhaps the most artistic part of the process.


White Winemaking Process

Once the white varieties, which really look more green-yellow, are delivered and sorted the fruit will go straight from the crusher-stemmer to be pressed very gently. Skin contact time for white varieties exists, but it’s uncommon, and relatively brief, because it tends to coarsen the texture. Some winemakers prefer the Champagne technique, which bypasses the crusher so that whole clusters are pressed. This is intended to minimize astringency.

So, for whites, unlike reds, pressing is the same day as harvest and only the grape juice is fermented. Stainless steel tanks for fermentation were a boon for all winemaking because they’re so clean, but for white winemaking they also allow us to do a cold fermentation. Since the fermentation produces heat, it was difficult to combat it in the old wood or concrete tanks but these days stainless-steel tanks, with double-walled sections that allow for easy cooling can be purchased and a food-grade coolant flows between the double walls to control the fermentation temperature.

This is important stylistically because if the wine warms up the heat tends to cook off the delicate, fruity aromatics we enjoy in our whites. Cold fermentation (we ferment our fruity whites at around 50 F.) makes the yeast sluggish and takes weeks to finish up.

Malolactic Fermentation and Clarification

While reds routinely undergo malolactic fermentation (ML), with whites the winemaker is more cautious and it becomes more of a stylistic decision. The caution exists because ML reduces the total acidity and the wine may be less lively as a result (whites are generally higher in acid than reds). The main grape acids are tartaric and malic.

Chardonnay in binML is a technique most often associated with Chardonnay and here’s how it works: Bacteria is added to the new wine which causes tart malic acid to convert to soft lactic acid. ML also creates a byproduct, called diacetyl, which smells and tastes buttery, so the winemaker might choose to go with ML to reduce the acidity or because he wants the buttery character and slightly oily texture or both. Depending upon his stylistic goals he can even do ML for only some of the wine and blend it with non-ML wine. In our sunny California climate, our winemaker isn’t keen on reducing acidity of our Chardonnay and, for him, the butter character competes with the fruit, so he’s not a fan of ML.

When the white wine is made, clarification begins and barrel aging is completely optional. If the winemaker wants to maximize fruitiness, he will probably avoid barrel aging, use larger cooperage or keep it brief. The oxidation takes away from freshness and oak flavor can interfere with fruitiness. But, if he’s looking for a little greater weight and complexity, barrel aging is a good option.

Chenin Blanc In CrusherFor some whites, such as Chardonnay and Sauvignon Blanc, the winemaker may prefer to delay clarification and age the wine on the spent yeast cells and grape solids (the lees). This technique, which is called aging the wine sur lies, gives the wine a round, creamy texture, a toasty character and also seems to play down the oak. Our winemakers is enthusiastic about this technique for our Chardonnay and takes it a step further by stirring the lees up into the wine, a technique called battonage, once or twice a week as the wine ages.

Thorough clarification and stabilization for whites is important because there’s no color to disguise the haziness and, in many cases, the wine hasn’t been through ML and needs to be prevented from attempting to complete the ML spontaneously.

When we’re finally ready to bottle, it’s a critical moment in the wine’s life. As the wine is transferred from a large container into a very small one there’s the danger of picking up excess oxygen and it’s extremely important to be attentive to each step of the process.

BottlingHere at Goosecross, we bottle a total of 5 or 6 days of the year, so purchasing the very costly equipment doesn’t make much sense. There are several mobile bottling companies available to come to the winery with all the equipment needed for successful bottling right in the back of their truck. They’re also employed by wineries who want to experiment with alternative closures, like screw caps, without investing in the new equipment.

After bottling, the wine usually goes through an awkward phase called bottle shock, which can last for several weeks, delaying its release. In addition, the winemaker may decide that the wine will be improved by additional bottle age, which is why it may take a red wine as long as 3-4 years to reach your table. The vast majority of winemakers consider the wine drinkable upon release, even though it may have the potential to improve further, and additional bottle aging is up to you! Cheers!