It’s almost a cliché – the image of the winemaker sitting in some kind of laboratory perfecting the blend for a final wine. In truth, it’s much more hands on. Wine is made in the cellar, after all, using tried and true methods and careful handling.
For the commercial winery, the selections of barrels for blending can be very arbitrary – a final quantity taking precedence over a final quality. The micro-winery has a much greater incentive to strive for quality, having limited resources from which to create a final blend.
The Final Blend
The concept is simple enough. Let’s say, you have three barrels of the same white wine. You used three different yeasts to ferment the sugars, one American Oak barrel, one French oak barrel, and one stainless steel barrel. One of the three barrels finished malo-lactic fermentation (MLF). One barrel did not go through MLF. One barrel never completely went dry, but did go through MLF.
Racking all three barrels would certainly make a complex wine, from the sounds of it. But would it be the best wine?
A bench trial (aka tasting) suggests that two barrels and ten gallons of another are to be combined into the final wine. The quantity is racked (drawn off the lees) to a container. After a gentle mix and final tasting, the wine appears to be what you thought it should be. But what happens now? How should you prepare it for bottling?
The next steps take us back to the lab for some simple analysis of the wine’s SO2 (sulfite levels) and pH (acid levels). A simple countertop kit can measure both SO2 and pH. An off-site laboratory can do the work for you – at a cost. (*One good website with winemaking tips is www.Vinoenology.com)
First thing is first. An addition of sulfur should be made to protect the wine from oxygen. If possible, any open space (ullage) above the surface of the wine should be sparged with gas. Nitrogen and Argon are great for sparging tanks, barrels, and bottles.
Chilling the wine at this time can also help the subsequent fining and filtering process. Simple tank attachments or wine inserts that circulate cool water can do the trick, but so can an airtight room and an air conditioner (ie; a cellar or garage). The idea is to maintain a cool temperature to help any final colloids settle out. It also slows any microbial spoilage, much like refrigeration does for food.
What is fining? Fining is the addition of specific ingredients in order to illicit a change in the stability and/or the aromatics and/or palate of the finished wine. A few things that can be ‘fined’ or removed from wine include: proteins; phenolics, tannins, and aromas.
Additives like Bentonite, which aids the precipitation of proteins, benefit from being added to a cooler wine (<50˚F). Bentonite is typically a grey clay which is combined in a one-to-two ratio of Bentonite and hot water to create a slurry. The slurry is added to the wine while mixing/agitation and then allowed to settle.
Bentonite is helpful in stabilizing the wine against heat exposure. It binds with proteins which become visible when the temperature rises to the temperature of a forgetful consumer’s trunk in the summer sun, for instance.
Adding too much Bentonite can strip the wine’s flavors, so bench trials are recommended. A typical addition of Bentonite can range from 0.5–5lbs / per one-thousand gallons).
After a typical Bentonite fining, the wine should become clear. The clean wine should be racked from the settlings. Some winemakers will filter the wine at this stage.
Protecting against heat exposure should be mirrored by stabilizing the wine against extreme cold.
Cream of Tartar (COT) is a very fast and easy treatment that can protect the wine from developing wine diamonds (aka tartrates). Tartrates are the physical manifestation of tartaric acid in the wine. Tartaric acid binds together when cold, but does not absorb back into the wine.
At this point, the wine should be cold – as close to 30˚F as possible. (*Note – If you can only get the wine to 45˚F, that’s good enough.) A small amount of COT powder should be sifted into the wine while mixing. Mix for at least one hour.
Over the course of the next few days, the COT will bind with the tartaric acid in the wine and precipitate out.
No trials are needed for COT. A standard addition of 1-3g/L can help precipitate a significant amount of tartaric acid.
Now that the wine has been blended, fined, and cold-stabilized – it’s time to filter the wine. Selecting the correct type of filter is an important step in this procedure.
A few questions to ask yourself before purchasing filters: Does the wine have any problems that require a sterile filtration? Does the wine have any residual sugar? Is the wine meant to age or be enjoyed soon after bottling?
Sterile filtration is suggested for problem wines (ie; wine with brettanomycees, excessive volatile acidity) and sweet wines.
The theories and practices of filtration vary widely. The main idea is to remove any potential problems that might appear in the bottle. The tighter the filter, the more particulate the filter will remove from the wine. Standard wine filters can remove items as large as 10 microns through 0.25 microns.
Depth filters are popular in commercial wineries, but other filters (cartridges/module) are just as good and less expensive. The important thing is to remove particulate by passing the wine through a screening system. The process protects the wine against degradation.
A simple series of 10” canister filters – a 10-micron and 5-micron – set up in line, between two containers can do the job quickly and easily. A pump is best for moving the wine through the filters.
The wine should be should be filtered directly from the COT settlings, while cold, into a sparged (gassed with nitrogen or argon) sanitized/clean container.
The end product is ultimately the patient that we are treating, here. Do we, as winemakers, want our wines to be okay, good, great, or the best they can be? I know what my answer is. What’s yours?