The grape genus Vitis splits into three natural groups based on geographical location: North American, Eurasian, and Asiatic. There are roughly 25 to 30 species of American origin and about the same number for Asia. But there is only a single grape species for Eurasia, the Vitus vinifera. Vitis vinifera is itself comprised by the wild grape vine Vitis vinifera sylvestris (commonly referred to as V. sylvestris) and the cultivated grape vine Vitis vinifera vinifera (commonly referred to as V. vinifera). So, all the well-known varieties/cultivars of grapes used for making wine today (such as Cabernet Sauvignon and Chardonnay) are members of a single species of grape vine, V. vinifera, and are the result of some combination of natural mutations and human tinkering over the course of several thousand years.
There is no clear point in time where the cultivated V. vinifera became distinct from V. sylvestris. In fact, hybridization occurs naturally between the two subspecies and occurred continuously throughout ancient times. We know that the native range of that the wild grape vine V. sylvestris included the Mediterranean shores of modern Lebanon and Syria as well the border between Syria and Turkey. However, there is archeological evidence of grapes being cultivated far outside the native range of V. sylvestris and into the far reaches of Israel, Egypt, and ancient Babylonia inside the geographical known as the ‘Fertile Crescent’.
The cultivation of grapes did not occur in a vacuum, but was part of the overall development of agriculture in the Fertile Crescent. Archeological finds indicate that wine was being made on a large scale as early as the 4th millennium B.C, in the ancient city of Godin Tepe in western Iran. In addition to the traditional archeological evidence of wine making such as finds of broken pottery, some of the pottery still had residue that was subjected to an in-depth chemical analysis that confirmed the presence of grape products (assumed to be wine). So, in the ongoing debate between wine people, beer people, and mead people over who started brewing first, the wine people now have scientific proof that puts start of intentional wine making back to at least the 4th millennium B.C.
The cultivation of V. vinifera, and presumably the making of wine, spread from Iran and the Fertile Crescent throughout the Middle East and Turkey eventually making its way to Greece. The Greeks spread viticulture to many locations around the Mediterranean including Italy and southern France; the Romans continued the spread viticulture throughout Western Europe. Fast forward through several thousand years of history including the dark ages, the middle ages, and the renaissance and we get to modern viticulture (growing grapes) and viniculture (making wine) using any of several hundred cultivars of V. vinifera which humans have new carried around the globe.
So how do we make wine. It’s easy. Crush the grapes; press out the juice; pour it into a vessel; and wait. Wine will happen; it can’t not happen. It might be good wine (lots of great commercial wine use spontaneous fermentation). But it might be terrible wine as well. To ensure success then, most wine makers inoculate with cultured yeast (someone got lucky with a spontaneous fermentation and has been culturing the yeast ever since).
First off, we need to grab some grapes. I guess we need white grapes to make white wine and red grapes to make red wine, right? Not exactly. V. vinifera grapes generally come in two types: green grapes and black grapes. There are other colors as well, but they are just not as common as green or black grapes. Regardless of the color of the skin, the flesh of the grapes is generally colorless ranging from pale green (green grapes) to pale grey (black grapes). And the juice from V. vinifera grapes is also generally colorless ranging from pale green (green grapes) to pale grey (black grapes) – amazing how that works out. Therefore, white wine can be made from almost any variety of V. vinifera grapes, but red wine is made from black grapes (or blends of grapes where the majority of the grapes are black).
Thus, we can make white wine from Chardonnay grapes which are green; Gewürztraminer grapes which are dark pink; and Pinot Noir grapes which are black. Yes, you really can make white wine (Blanc de Noirs); rosé wine (Sancerre Rosé); and red wine (Burgundy) from 100% black Pinot Noir grapes. How can that be you ask? Great question. And the answer is that white wine is made with a white-wine process and that red wine is made with a red-wine process (duh). The making of rosé wines straddles the fence.
The white-wine process is as follows:
1) Crush the grapes 2) Press the juice from the crushed grapes 3) Clarify the juice (let the pulp from the crushed grapes settle in a tank) 4) Transfer the clarified juice to a fermentation tank 5) Inoculate with an appropriate wine yeast 6) Wait until fermentation is complete (with some caveats) 7) Clear the wine using fining agents or power filters 8) Bottle the wine
Dry white wine is made by letting the yeast consume all the available sugar in the juice. Semi-dry to semi-sweet wines are made by chilling the fermentation tank to just above freezing right before the yeast consumes all the sugar. This puts the yeast into hibernation. Then the wine is power-filtered through increasingly fine filter pads until the live yeast is filtered from the wine. Finally, a big dose of potassium metabisulfite is added to ensure that refermentation does not occur once the wine is in the bottle.
The red-wine process is as follows:
1) Crush the grapes 2) Transfer the mixture of juice and skins (known as must) to a fermentation tank 3) Inoculate with an appropriate wine yeast 4) Work the must until fermentation is complete a. The grape skins (and pulp) still have juice in them b. The yeast will ferment the juice in the skins c. The resulting CO2 will puff up the skins like little balloons so they will rise up from the liquid below d. The skins also form a cap which traps CO2 from the liquid below while it ferments e. Thus, the skins will rise up out of the liquid below and will begin to dry out f. Fermentation releases heat, so you get warm moist skins which can become a great environment to grow many bad organisms, so i. You push the skins back into the cooler liquid below two or three times a day (punching down the cap) ii. Or you pump cooler liquid from the bottom of the tank on top of the skins 5) Release the free-run wine from the tank (whatever wine flows out without pressing) 6) Transfer the skins to a press 7) Press out the remaining wine from the skins 8) Age the wine (typically in barrels, but tanks with wooden slats can be used) a. Premium wines typically age the free-run wine and pressed-wine separately to be blended to taste at the end b. Bulk wine will have the free-run wine and pressed-wine blended before aging 9) Clear the wine using fining agents or power filters 10) Bottle the wine
Some premium wines will have an extended period of maceration (soaking the finished wines on the skins) after fermentation is complete to extract as much color, aroma, and flavor from the skins as possible. This is one way to make amazingly intense wines. It is also a way to make hideously harsh crap. Know what you are doing if you choose this path.
Many red wines and some white wines will undergo malolactic fermentation at some point in the process. Tartaric acid is the dominant acid in grapes, but grapes also have significant amounts of malic acid. Malic acid is tart and harsh on the palate. Certain bacteria (Oenoccocus Oeni) will convert malic acid to lactic acid which is softer on the palate and can provide a creamy, oily mouth-feel. This malolactic conversion is not true fermentation, but it does release CO2 resulting in the appearance of a “secondary” fermentation in the wine.
Alright, let’s go get some grapes. Hmm, you better live on the west coast or near one of the handful of places in the Eastern or Southern US where the climate is moderated by proximity to an ocean, a river valley, or the Great Lakes. Otherwise, you aren’t getting fresh V. vinifera grapes unless you have friends willing to jointly buy several tons of grapes and pay for refrigerated shipping. Otherwise you are buying kits.
Kits range in price starting around $160 for all-juice kits (no concentration); down to about $120 for high-quality concentrate kits; further down to around $80 for mid-quality concentrate kits; and at the bottom around $40 for crappy cans of concentrate. What differentiates the kits is:
- All juice is just that. 23 Liters (6 gallons) of pure wine grape juice. You put it in a fermenter and go. This provides the truest flavor profile for the wine.
- High-quality kits are around 16 liters (4 gallons) of juice concentrate. You add 2 gallons of water to get to normal concentration and then ferment.
- Mid-quality kits are around 10 to 12 liters (2.5 to 3 gallons) of juice concentrate. You have enough water to get to 6 gallons and then ferment.
- The canned stuff is basically crap. You add one or two cans of concentrate and a bunch of sugar into the primary. Then add enough water to get to 5 or 6 gallons.
The key is that the more concentrated the kit, the less of the true grape varietal flavor and aroma carries over into the final product. It is possible to buy premium wine kits that have the juice still on the skins, but they are hard to come by. You need to order in advance from some dealer, and the must comes refrigerated or frozen in 5-gallon pails. I’ve seen friends use them, but I have no relevant experience.
So how are wine kits made, in particular red wine kits? We know that red wine is made by leaving the juice in contact with the skins during fermentation. But kits aren’t fermented (otherwise, they would already be wine). Here is one quick summary:
White grapes are pressed, and the juice is pumped into a settling tank. Enzymes are added to break down pectins and gums, which would make clearing difficult after fermentation. Bentonite is added to the juice and re-circulated. After several hours the circulation is shut off, and the tank is crash-chilled below freezing. This helps precipitate grape solids, and prevents spoilage.
Red grapes are crushed, sulfited and pumped through a chiller to a maceration tank, where special enzymes are added. These break down the cellulose membrane of the grape skins, extracting color, aroma and flavor. The tank is chilled to near freezing to prevent the must from fermenting. After two to three days the red must is pumped off, pressed and settled much the same way as the whites.
When the tank is settled, and the juice almost clear, it is roughly filtered, the sulfite is adjusted, and it is either pumped into tanker trucks for shipment to the kit facility, or into a vacuum concentrator.
Vacuum concentrators work like the reverse of a pressure cooker. By lowering the pressure inside the tank, water can be made to boil at very low temperatures. By boiling the juice at low temperature browning and caramelization are prevented. The water comes off as vapor, leaving behind concentrated grape juice. Because some aromatic compounds can be carried away in this vapor, a fractional distillation apparatus on the concentrator recovers these essences, returning them to the concentrate after processing.
Enzymes are used to extract color, aroma, and flavor from the skins of black grapes. They do a good job of capturing the basic flavor profile of the grape variety, but it is not the same as fermenting on the skins. It is similar to making beer with extracts versus all-grain. You can get good products from extracts, but finesse is only achieved through total control of the mashing process. It is the same story when making wine. Concentrate kits make good wine. Exceptional wine requires working with fresh grapes.
So, what does an aspiring winemaker do if he doesn’t live where V. vinifera is grown and doesn’t want to work with kits? The answer is hybrid grapes.
Starting in the late 1800s, the French had a little problem. Some “important person” in Germany imported grape vines from the United States to plant as curiosities. Top Men did that kind of thing for amusement – creating gardens of plants from around the world. The problem is that North American grapes evolved with a nearly microscopic insect called phylloxera which eats the roots and leaves of the grape vines (the insect lives underground all year except for a few weeks when they go airborne to reproduce). It turns out that V. vinifera had a bit of trouble dealing with phylloxera, and phylloxera destroyed 3 million acres of vines in France. Wine production was cut in half, and the trend was going from bad to worse. Fortunately, some professor in Missouri figured out you could graft V. vinifera to American rootstock and the vines would survive, even thrive (and that’s an entirely different article). European wine was saved!
Until the gentlemen from Missouri saved the day, viticulturists (people that grow grapes) in France were frantically trying to hybridize V. vinifera with American grapes to get something to survive. And they had some successes. Several French/American grape hybrids were produced then that are now grown throughout the United States, but they have since been regulated out of existence in France to preserve the cultural integrity of French wine (and because the grapes aren’t anywhere near as good V. vinifera). In the 1940s, a Wisconsin farmer named Elmer Swenson began hybridizing the French/American hybrids with American species found in the upper Midwest trying to find varieties that would survive in cold climates. Elmer also had a lot of success. Many of his grape varieties are in production around the Midwest. In more recent years, Cornell University in Geneva, NY and the University of Minnesota have continued to have great success creating many new cold-hardy varieties. Thus, wine grapes can now be grown in many places where V. vinifera cannot. And while many of these varieties can produce wine that is quite good, none of them have reached equality with V. vinifera. But if you live in Iowa and want to make wine with local grapes, you need to make do with the hybrids that grow close by.
Finally, let’s make some wine.
Remember that apple crusher we just bought to make cider. I got bad news. It won’t work. You need to go drop another $500 on a grape crusher/destemmer. You put the grapes in the hopper and turn the crank. Crushed grapes fall out of the bottom, and the stems traverse a down a long tube of sorts to the end of the destemmer. The destemmer part works, mostly. But you still need to stick your arms into the crushed grapes and pull out the pieces of stems that make it all the way through.
Then we’ll splurge and buy a nice big wine press. It’s big, and it’s heavy, and it’s awkward. So, we’ll mount it to a platform with castors – castors that don’t lock. Note when I say we, I mean the dude that bought the press; it ain’t mine. Since the castors don’t lock, make sure you have 5 or 6 other people around that are willing to grab on to handles that don’t exit to hold the press in one place while you crank away.
And the beautiful juice flows out of the press. Wait, why isn’t it colorless. I was told that black grapes produce colorless juice. Well, that’s V. vinifera. This is a lovely French/American hybrid called Frontenac created by the wonderful folks at U of MN. Unlike V. vinifera, the pulp of Frontenac is purple and the juice is a vivid red. Even though we are following a “white-wine” process and pressing juice from the fresh grapes, we will be making a medium-bodied red wine. The reason we are not fermenting on the skins is that Frontenac is notorious for smelling of green vegetation (i.e., like “someone just opened can of green beans”). The common wisdom is that avoiding skin contact during fermentation reduces the undesirable aromas in the wine.
Oh, and the acid level of Frontenac is about double the acid level of high-quality V. vinifera grapes. So, don’t be thinking you’re making a nice dry red wine. You’ll be making a sweet wine (or in my case, a type of mead called pyment). There’s reason why no one pays 50 bucks for a nice bottle of Frontenac from Iowa.
Once all the juice has been extracted from the grapes, the outer frame is disassembled exposing the “cake” which is the dry, compacted grape skins. In this case, a nylon bag is used as a screen to prevent the skins and seeds from being pushed out between the wooden slats in the frame. The cake is dumped into a handy bin and then disposed of in a way that honors Gaia (e.g., composting, feeding to livestock, sending it FedX Ground to your Representative, etc.).
Now you are ready to head to the brewing room. Refer back to “Waiting is the hardest part”. Fade to black.