18 replies to this topic

[tgriffin]

I am currently (right now) making my first grape wine from grapes (I froze last fall) and I'm trying to get the must right before pitching the yeast. I am using Frontenac grapes and have 9 gallons of must. SG 1.094...I figure that's ok. The real question is the acid level. I tested a sample I filtered through a coffee filter with my inexpensive titration setup, and was shocked to go through the whole syringe and not get the color change. I refilled it and kept going and it went blue/black at a hair over 1.1% TA. I only have test strips to measure PH and the color doesn't seem like a close match to any on the bottle, but my best guess is 3.6 PH. I would have thought that would be lower with the high TA.

Now the question I need answered ...do I need to do anything at this point to bring down that TA? The Morewine guide I am following says to consider a MLF if the TA is .9-1.0, but doesn't say what to do if it is over that. I am planning to do a MLF, but I don't know how big a drop I can expect from that.

Thanks for the help,
Tom G
Windom, MN

[red_feet]

If the SG is really 1.094, which is a bit high IMO, I would expect the TA to be somewhat lower than what you indicate (I've never used Frontenac, so am not familiar with typical sugar/acid levels). I'd wonder about the NaOH solution. How fresh is it? NaOH absorbs water over time, so would take more to neutralize the acid. Is it 0.1N or 0.2N? 0.1 would take double the amount to neutralize, compared to 0.2.

Ken

[tgriffin]

The NaOH solution is 0.2N and was opened less than a week ago.

Tom

[red_feet]

So you're using 0.2 N NaOH with a 15 ml sample?

Ken

[tgriffin]

Yeah, that's correct.

[red_feet]

If it were my must, I'd be tempted to reduce the acid preferment, I use potassium carbonate, others use potassium bicarbonate or calcium carbonate. I would take acid down to about 0.9%, ferment, then cold stabilize to drop more of the tartrate.
Others may give you other ideas to consider.
I hope it goes well for you.

Ken

[tgriffin]

I re-tested with a new sample, but no joy, it came out about the same. I hope I'm doing the test right. I'm just following the directions on the box. I have been adding the NaOH to the sample and swirling it to mix. Each drop turns blue briefly, then gets mixed in. The whole sample slowly gets darker. I stop when the drops don't make it darker and the thin edge of the swirles looks blue/black instead of red. Does it sound like I'm doing this right?

[red_feet]

That sounds right. Red musts are more difficult to read than white, so the preferred method is to use a pH meter, and titrate to a ph of 8.2. That way you don't have to guess as to when the final color change occurs. Before I had a pH meter, I would place a light behind the container to more easily see the color change. You could also dilute the must with distilled water to more easily detect the change. Adding distilled water doesn't change the amount of NaOH needed to neutralize the sample.

Ken

[tgriffin]

Well, I ended up adding 3 teaspoons of calcium carbonate (as that's what I had) and retesting. I was pleasantly surprised to see the acid down to 0.9% TA as I had only added enough (according to the bottle) to bring it down 0.1%. The PH now seems to be reading about 4, so I have the strange situation of having too high a TA and also too high a PH. What up with that?
I went ahead and pitched my yeast starter and went to bed. I just checked on it a few minutes ago hoping to see it bubbling away, but nothing. Apparently I screwed up and the must wasn't warm enough, as I took the temp today and it is still only 52 deg. Its sitting in my 65 deg kitchen. I took the grapes out of the freezer on Friday, but I guess it takes longer to reach room temp than I thought. I went ahead and wrapped an electric blanket around the fermenter to speed things up a bit. Now I am wondering...Did I kill off my yeast by pitching them into the cold must? And do I need to worry about oxidation from the extended period between the crush and the co2 protection from fermentation?

Tom

[glenn1959]

I wouldn't look to speed up, the longer on the skins the better extraction.

[Wade's Wines]

Don't worry Tom, you're going the right direction, getting it warmed up.
Spoilage thingies don't like a cold must much either, so don't worry.
Your yeast will probably be fine and take off as it warms up. It keeps in the fridge for a long time so a little cool must should just cause it to take a little longer to start, waiting for warmer temps.

[tgriffin]

I'm not trying to speed up fermentation, only to speed up the warming of the must to room temperature. I guess I'm being impatient as the morewine guide says it can take 1-3 days for fermentation to start. The kits, skeeterpee etc that I have made in the past showed signs of fermentation in maybe 12 hours...but they weren't as large and didn't have crushed fruit, just juice. At this point my biggest question is Did I shock/damage my yeast by pitching them into must that was probably in the mid to upper 40 degree range, and do I need to start making another yeast starter?

Tom

[tgriffin]

Ah, answers to questions I hadn't quite posted yet Looks like I need to be a little patient and give it a change to do it's thing. Thanks all who have responded.

Tom

[rawlus]

Can't really shock dry yeast. They will wake up when the temp is right.

[rawlus]

If the yeast were hydrated, a starter or liquid, shocking is possible. Usually going from cold to warm though.