Wednesday, October 29, 2008

More Power Failures and an Acetic Acid Alert!

On Tuesday morning I awoke at 7:30am to a call from Rest Assured Alarm Systems. The power was out again the Shier as of 5:30am. Considering our apartment building was swaying in the high winds, it was not all that unexpected. The power stayed off until 9:30am, knocking the server out. I researched the power restore features of office servers and it turns out that many newer computers have a BIOS power management option that allows the computer to restore the computer to an on state following power restoration. When I return to the Shier, I will check to see if my computer offers this option. In the meantime, I am hoping that everything is okay because I cannot access the Winepod remotely. Based on the fermentation progress chart, I project the primary fermentation to conclude on Sunday with a brix reading of zero. I will rack to carboys at that time.

Meanwhile, I received my juice analysis from the Cornell Wine Lab. Even though I was careful to freeze the sample and send it by Federal Express for next morning delivery at a cost of $34, I did not hear back from the lab supervisor, Ben Gavitt, until 8 days later. It turns out he was away at a conference. Since I also was away that week at a conference in Washington, D.C., I didn't complain. These are the results that I was provided:

Attached please find the analysis
pH 3.29
TA 9.9 g/L
Glucose 96.7 g/L
Fructose 99.4 g/L
Res Sugar 19.6%
Alcohol 0.7%
Tartaric 2.1 g/L
Malic 5.0 "
Lactic 0.2 "
Acetic 0.7 '
The acetic is quite high. I would watch it.

Acetic acid at 0.7!! Oh no. Some acetic acid is okay to make for a complex taste, but 0.7 is not where I want to be before fermentation. It is said that 0.6 is the lower limit for human taste perception of acetic acid, which tastes and smells like vinegar. 1.3 would be undrinkable. That said, the must does not smell like vinegar, which is a good sign.

I paid particular close attention to the fact that residual sugar was 19.6 percent and alcohol was listed as 0.7%. Since the vineyard measured juice brix at 20.5 and I confirmed my starting must at 20.6, a measurement of 19.6 shows evidence of fermentation with wild yeast in the sample bottle. Consequently, I am a little hesitant to accept the high acetic acid measurement. Mr. Gavitt assures me that the sample was refrigerated at 33F for the week he was away. Still, fermentation in the sample bottle with wild yeast could certainly raise the level of acetic acid. Further evidence of this can be seen from the TA (total acidity) measurement of 9.9 g/L. The vineyard reported TA at 8.3 g/L. See the October 18 Riesling results:

I expect to receive some benefit in acid reduction from cold stabilization of the finished wine, but these initial results still leave me concerned. I might need to invest in an acid test kit. My nose is still the best acetic acid tester, though.

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