Wine kits are so wonderful because they tend to be easier and more predictable than just starting from a fresh batch of grapes. Kits have instructions to follow and you’re right, most of them only have you measure the specific gravity (or Brix) to monitor the fermentation. The idea is that the acidity levels are “built in” and if you add all the powders, do all the mixing and follow instructions, the final pH and TA (and as a result, the final flavor balance) is predestined and will come out “just right.”
Or will it? “Just right” depends of course on your taste and the tastes of the person who engineered the kit in the first place. Personally, I think that kits are made to be crowd pleasers, which is another way of saying they skew towards rounder, sweeter, and less acidic than you might want. Now, I’m not saying that they’re made to have dangerously high pH’s (low acidity), but there’s no doubt that lower acid level contributes to a wine that’s easier to enjoy sooner, something that some kit winemakers might appreciate.
Competition judges, however, tend to be trained and experienced wine tasters if not winemakers themselves. That means they appreciate and will look for a competition entry to approximate the quality and typicity of professionally-made wines, which often carry a decent amount of alcohol, acidity, tannin, aroma, and character. I’ve got to be honest and tell you it’s tough for shelf-stable concentrate and powders to possibly approximate the complexity of a fermentation made from real fruit material, with the skins, seeds, warts, and all.
All of which means that I think you’re right, you probably can improve your kit wines by paying a little bit closer attention to their acid balance. Doing this is no easy (or cheap) feat. It involves testing at multiple points and making measured tweaks when necessary and appropriate. I could write an entire issue of WineMaker magazine on the topic and indeed whole articles here have been. To answer your specific question, and to give you some direction in which to head, see my tips that follow for a list of when you might want to pay a bit more attention to the acidity (or lack thereof) of your wine. Some kit wines are sometimes a bit, shall we say, lackluster . . . which means they just might not have the guts to stand up to robust acidity (this can happen with fresh grape winemakers too!). That’s a caution to listen to your material (kit or otherwise) and try to get a sense of where it can go — but also where it cannot go. Please remember that when adjusting acidity, always do bench trials, taste as you go, and be careful of over-acidifying. If that happens, you’ll definitely find your wines out of balance.
Points at which commercial wineries measure acidity (critical points for home winemakers are highlighted in yellow):
• In the field (for deciding when to pick): TA, pH, malic acid
- Home winemakers may be able to get by or rely on taste. I don’t do the above for most of my picking decisions, I go on experience. However, if you’re getting new grapes from a new vineyard for the first time, these numbers can be a good baseline and can help you with your decision.
• After crush/juice phase: TA, pH, malic acid, volatile acidity (VA)
- These are your baseline numbers on which to base your tartaric acid adjustment for fermentation and are very important to measure. If you don’t have the equipment for titration and a pH meter, send out to your closest local wine lab.
- The VA measurement is to get a baseline to measure future activity against. High VA is often a sign of yeast or bacterial spoilage and tends to increase as wines age.
• After primary fermentation: TA, pH, VA, malic acid
• During malolactic fermentation: Malic acid every 2 weeks
- Home winemakers can probably get away with measuring every 3–4 weeks.
• After completion of MLF: TA, pH, VA, malic acid
• Monthly: VA (to keep track of possible spoilage)
- Home winemakers can probably get away with measuring VA every 2–3 months.
• Bottling: pH, TA, VA
- Except for VA, home winemakers can get away with just having some going-to-bottle numbers, that I’d hope they’d check to make sure that the wine wasn’t getting attacked by spoilage organisms.