Good Chemistry

Chemical analysis can help you make a better decision about the optimum time to pick your grapes. Good chemistry is important to good winemaking. It's also helpful in a lab partner. I haven't had this much fun since Kendal P., bless her heart, was my lab partner in 8th grade science and I received my worst grade ever as she was a serious distraction. This time I kept all hands on deck and my eyes on the pipettes and the beakers and the LCD display and came away with some useful information.

I took a 100-plus random sample of berries from different parts of the clusters from each row of the Tempranillo block yesterday evening, hand crushed them in a baggie and measured the sugar: 22 brix. I purchased a Milwaukee pH meter and an acid measuring kit and not sure how to use them Coyote Karen volunteered to show me how so I went to her kitchen lab with my specimen. The reason she is called "Coyote" Karen is her vineyard is host to the crafty critters and they and men alike howl at her beauty. She is something of a scientist and I watched intently as she she showed me how to calibrate the pH meter then measure my sample. The reading came in at 3.63.

Next, she showed me how to test the acid. You do this by seeing how many cc's of indicator solution you drip into 50 cc of distilled water combined with 10 cc of grape must and 3 or 4 drops (we used 4 drops) of another solution until you reach 8.2 on the pH meter (or until the liquid becomes dark). Because it's not exactly certain when the liquid becomes dark, use of the pH meter is a bit more scientific. Being a scientist Coyote Karen has all kinds of beakers and pipettes and measuring devices and a machine that vibrates when you put a beaker on it and you put a little magnet at the bottom of the beaker and the magnet spins around creating a whirlpool to keep the mixture mixed and she puts her mouth over the pipette and pulls the poisonous indicator fluid (10 cc's) up the pipette and she doesn't waste a drop and I'm thinking if anyone in the neighborhood goes to their car and finds the gas siphoned then she's the #1 suspect. She tests some finished wine that has way too much acid in it and the wine doesn't taste good but it's not a total waste because she'll hang on to it and some time in the future she may blend it with a wine that is way too low in acid.

Being a good teacher she then insists I try (there is no better way to learn than by doing) and my butterfinger hands pick up the glass pipette and I start sucking up the poisonous liquid and as it rises up the pipette my saliva starts going down the tube and resting on top of the liquid and she starts laughing and making fun of me and I swear I wasn't drooling over her although the chemistry is good. She tells me to multiply the 10.5 cc of solution I dropped into the beaker to raise the pH to 8.2 by a factor of .15 and the resulting acid level of 1.57 doesn't sound good to me at all and I read the directions and the directions say to use a correction factor of .075 and she says that's because I used 10 cc of grape juice instead of 5 cc and despite the fact I would have ruined my wine based on the information she gave me the chemistry is good. The acid recalculation is .785, which, I am told, is a good level.

In summary: The brix are 22; the pH is 3.63 and the acid is .787 and she says those are good numbers. So, here's the decision to be made. Should I cut the water and try to get the brix up to 24 next Sunday in which case the acid is likely to drop a little and I'll have good numbers for making a good wine?

Or, should I water the vines a little tomorrow and plan on harvest in 2 weeks? Two weeks from now I could get the brix up to about 25 (keeping it from reaching 26 or 27 by adding a little water) and the grapes will be full of sugar and riper and the seeds will be darker brown and crunchy but the acid will drop maybe a little too much. You can always do a little acid adjustment (most winemakers do by adding tartaric acid) and if the brix get too high you can always add water to the must (many winemakers do). If the brix get too high then the wine may have too much alcohol and it may "burn". Waiting two weeks would allow me to make a "bigger wine". On the other hand if I wait two more weeks the birds may get more of the grapes and I'll be left with less, and, I'm dealing with younger vines (only their 3rd leaf) so perhaps I shouldn't get my hopes up about making a big red wine.

To pick or not to pick? Experienced winemakers, vineyardistos and vineyardistas, what should I do?