Sunday, March 29, 2009

Lightning Strikes Wine!

Actually, the lightning came after my success with the acid reduction. I followed the advice of Tom Mitchell and added tartaric acid to one carboy, bringing the pH from 3.4 down to 3.2. Then I packed the carboy in garbage bags with ice and loaded the bags and carboy into the fridge. One week later I racked the wine off beautiful crispy glacier-like tartaric crystals. The taste is vastly improved, with a mild bite, but no grapefruit aftertaste. Aging will help, but I didn't even need a TA acid test to know that the wine is now remakably close to bottling condition. In fact, after racking off the crystals, I decided to bottle the leftover wine from the bottom of the barrel for some pre-bottling feedback at work. The only finishing touch from here, besides aging in bottles, will be to try to get the color right. For that, I plan to use a clarifier PVPP known as Polyclar. Polyclar removes haze causing polyphenols as well as yeast cells, which give the wine an orange glow tint. I'm shooting for the pale yellow-gold that most people typically associate with white wine.

Below is a photo of my calibration of the pH meter using the buffer calibration solutions. I picked up the calibration solutions from a store called the New Aquarium near Grand Central, in the city.

On Sunday night there was a strong thunderstorm. The motion camera went crazy and picked up a lot of lightning activity. The shot below is a streak that came down in the woods behind the house. I will check back for the tree that suffered this strike when I return next weekend.

Friday, March 13, 2009

Free Advice

I spoke with Tom Mitchell, the owner of Fall Bright vineyard, where I purchased the Riesling juice. Turns out that Tom purchased a portion of the 2008 Riesling grapes from another vineyard in the area, which he said was not his usual practice (now he tells me). He said that others who purchased the Riesling had experienced similar issues with acid, but mostly found the color to be too dark for their taste. He said he was conducting test to see about acheiving the proper color.

I gave Tom an explanation of my starting and ending TA and pH numbers and the steps I had taken thus far. His recommendation was unique. He explained that I was likely not getting enough of a reduction from my cold stabilization because the pH was too high. He recommended lowering the pH to 3.2 by actually adding more tartaric acid to the wine. He said that when I place the carboy back in freezing conditions for one week, the acid will drop. I will give it a try. Since it is too late in the season to stabilize in the garage, I will need to use the refrigerator as a wine freezer.

Monday, March 9, 2009

Taste and Color - So close, but so far away.......

I have entered mad scientist mode. After fining with a combination of Kieselsol and Chitosan and cold stabilization in the garage for two weeks, the wine tastes too tart. The initial touch to the mouth is sharp, which I kind of like, but the aftertaste is like grapefruit juice. Yeccchh. It seems clear from the taste that high acidity is the culprit. To be sure, I went out and ordered an acid test kit and a fancy electronic pH meter.
The pH meter was pricey at $45. I calibrated the meter using 4.00 and 7.01 pH buffered solutions. All three carboys read a pH of 3.4. Pretty good for a white wine. Now for the real test. The test kit included sodium hydroxide and phenolphthalein with a test tube and syringe. To determine Total Acidity (TA), the wine is placed in the test tube with a few drops of phenolphthalein. Sodium hydroxide (NaOH) is added one drop at a time with the syringe until the wine turns pink. I performed the test twice. First time it took 4 cc of NaOH and the second time it took 3.9 cc to get to pink. To get TA, the multiplier is 1.6 for the Sulfuric scale and 0.25 for Tartaric.
Sulfuric is from 6.2 to 6.4
Tartaric is from 0.98 to 1.0
For white wine the TA should be no higher than 4.9 for Sulfuric and 0.75 for Tartaric.
Now the dilemma. Riesling, being from Germany, is a cold weather grape. It grows well in the Finger Lakes. Cold weather grapes tend to have higher acidity because of slight increase in rot on the vine (simplified explanation). The acidity is desirable because it provides the wine with a crisp taste. I need to get the TA down to a desirable level without changing the pH or screwing up the crisp taste.
My options are: (1) to add some calcium bicarbonate (chalk) and risk altering the taste dramatically (adding three months minimum before bottling) (2) add water (cheap, but makes cheap wine), (3) dilute with low acidity commercial wine (expensive, but effective), (4) add some other type of carbonate like potassium carbonate which some say should only be done before fermentation and we are too late for that.
I also need to sweeten the wine to taste. For that I will use a sucrose and potassium sorbate combination that is often referred to as "wine conditioner".
Before doing anything, I plan to consult with the vineyard who sold me the grapes.
In addition to getting the taste right, I want my wine to look pretty too. That means getting it crystal clear brilliant. I tried filtering one of the carboys using the Vinimat gravity filter. Awful. I should have known when I saw the filter had a "made in England" stamp. When is anything ever made in England these days? It took nearly an hour to filter one third of the 5 gallon carboy and I basically lost a whole bottle's worth of wine just getting the wine to flow. This presents a danger to the wine because exposure will oxidize and ruin the very color and taste that I am trying to achieve by filtering. So I gave up and racked the last 2/3 of the carboy using my siphon pump and tube.
I also managed to get the Titrets to work great for the first time. To my surprise, the free SO2 was quite low. Around 20-25 ppm. So I added 1/4 teaspoon potassium metabisulfate to each. That should put the SO2 at around the 60-65 ppm safe range for each.