Newbie with Grapes

[JJGDC]

Hey everyone!
Picked up grapes Friday from the wine maker toy store 3 lugs of Zin and 2 of Petite Syrah. My initial readings are

Zin bucket #1
SG 1.21 @78degree
pH 4.04

Zin bucket #2
SG 1.22 @76degree
pH 4.03

Petite Syrah
SG 1.3 @78degree
pH 4.14

My question is with my TA calculation using a pH meter I titrated out that it took: Zin#1 7.7 mL of NaOH, Zin#2 7.25 mL, PS 7.5 mL all reaching pH of 8.2 assuming my technique is correct how much acid should I add to each bucket. Sorry for the college test! My numbers were Zin#1 TA= .58 need to add ~.07 grams per gallon? Zin #2 TA =.54 need to add ~.21 grams per gallon? PS TA = .55 need to add ~.17 gram per gallon?

Any advice would be really appreicated also the really high SG's are "worrying" me a bit.

Thanks JJ

 

[ibglowin]

First off your SG readings are not correct. You have misread your Hydrometer.

You can't figure out how much Tartaric acid to add just on lugs or a bucket. You (we) have to know how many gallons of must you have in each bucket.

Looks like you will need to add some acidulated water to help with the SG (as well as TA) but it all depends on you providing correct numbers and must sizes first.

 

[Bartman]

I agree with Mike that your SG readings are off, although I sympathize that it is really hard to get a good reading with a wine thief because the juice is so thick/cloudy (compared to a clean and simple wine kit).

But Mike, if he got 3 36-lb lugs of Zin split into two buckets, should start with about 4-5 gal of must and grapes end up with about 6 gallons of wine. Similarly, if he started with 2 lugs of Petite Sirah, he probably has about 7 gallons of juice and grapes and will end up with about 4 gal of juice. A little more specificity would be nice, but I don't think I could tell you exactly the volume of my grapes right now - the volume goes down about 10-15% each time I punch down the cap!

 

[ibglowin]

You have to have some sort of graduated cylinder like these to get a decent SG reading with fresh grapes. Use a small glass jar or beaker to carefully skim off ~100ml of juice from the top of the must. Carefully poor it into the graduated cylinder and remove any seeds or skins that made it into the beaker and or graduated cylinder. Insert the Hydrometer into the cylinder and let it do its thing.

Usually (3) 36lb lugs will make somewhere around 10-11 gallons of must. But only he knows if they are evenly proportioned or one has more than the other. Best way to get the volume is to just measure the height (inches) of the must (recently punched down if fermenting) and then measure (inches) the diameter across the top, divide by 2 (to get the radius) and calculate the volume using this formula:

V = (3.14)(r2)(h) or (Pi)(radius squared)(height)

This will give you a number in cubic inches. There are 231 cubic inches in a a gallon so divide your result by that number to give you gallons (US) of must.


Without a decent volume its pretty hard to give out any type of (decent) acid addition numbers.

 

[JJGDC]

Ok sorry I assure you that I am a much better chemist than a typist!

SG = 1.121 Zen 1
SG = 1.122 Zen 2
SG = 1.130 PS

The TA titration were correct I checked them 3 times.

The volumes are:
Zen1 6.712
Zen2 6.41
PS 7.01

Trust me a little bit I was trying not to bore you with the details. I have a BS in chemistry and know a bit of what im doing on that side just trying not to screw up on the art side of the grapes into wine.

Thanks JJ

 

[JJGDC]

So I guess my real question should be how the heck to I get the pH where it should be?

 

[ibglowin]

Adding Tartaric acid at the rate of 1.0 g/L will increase (in theory) the TA by 1.0 g/L and decrease the pH by 0.1 unit.

You didn't list units next to your volumes. I am guessing these are GALLONS of must???????? If so I converted over to Liters and came up with the following numbers:

In theory if you were to add ~50 grams tartaric acid to each must your TA would increase to ~7.5g/L which is on the high side of TA but still within a normal limit of 6-8 g/L. This would in theory drop your pH down to the 3.8 range.

Always add 1/2 of the amount you think you need and recheck you numbers

Since your SG's are also off the charts I would add the acid to some bottled or purified water (not distilled) first to dissolve it well. Probably at least a liter and maybe more to get your SG down in the 1.100 range (~14%ABV)

Stir it well and let it sit for an hour, stir it well again and then repeat your test. You want to make sure the acid is dissolved and mixed well.

 

[JJGDC]

Thanks Mike everything came back in line,

Added:
40g and 1.7 L to Zen 1 pH was ~3.8 with a TA of .73 SG 1.11
35g and 1L to Zen 2 pH was ~3.7 with a TA of .69 SG 1.10
49g and 2L to PS pH was ~3.8 with TA of .74 SG 1.090

THANK YOU!!!

So this is a theory question? I know MLF turns Malo-Lact Acid into Lactic, would this change (drop) the TA? and would it change the pH, I know MLA can have a pka/pH above 4?

Just wondering?

JJ

 

[ibglowin]

Lactic acid is a "weaker" acid than Malic so yes, this will change everything. pH will usually rise and TA will drop. You can recheck everything after MLB has completed and re adjust if way off the mark. Usually the change will not be all that significant (0.1-0.2 pH change) but every batch is different and unique. Some times you just have to do the best you can with the acid levels being the first priority (for taste) and then pH second priority. If you can't get the two to align properly you have to either blend with something that will help it all align or add a boatload of SO2 to protect the wine at the higher pH and just consume it quicker than maybe you would have liked to.

 

[JJGDC]

So after 6 days of fermentation,
Zin1 SG = 1.004 for the past 3 readings (one on tue two on wed)
Zin2 SG = 1.004 yesterday (tue) and this AM(wed) then 1.002 tonight(wed night)
PS SG = 1.010 yesterday and 1.008 for todays readings

Will take reading again in the AM but should I try and press tomorrow night or friday if these numbers hold? Tonight's punch down was the first time I didn't have a "cap" of fruit on the top of zin1 & PS buckets?

Also, as a side the last pH check which I will redo in the AM, was zin1 3.64, Zen2 3.65 and PS 3.88. I am not married to MLF but I was originally thinking about it.... I don't thing the Petite Syrah can handle it but if those numbers are correct and not just a byproduct of fermentation then what would you think about it on the zin?

 

[Diverdown066]

Out of curiosity, why SG and not brix?

 

[JJGDC]

Using a hydrometer, which I thought was the most accurate thing to test with?

 

[JJGDC]

Pretty sure my fermentation is finished or stuck! I've never had a fermentation stop above 1.000 and I am at:
zin1 SG= 1.002, Zin2 SG= 1.002 and PS SG= 1.002

What worries me is that Zin1 and the PS aren't forming a cap of grapes, temps have been pretty steady between 68 and ~85 degree F. There was one temp reading that got to 88 on the PS bucket.

pH and TA are Zin1 = pH 3.64 and TA .8, Zin2 = pH 3.72 and TA .8, PS = pH 3.86 and TA .9

Im thinking MLF for the zin's and leave the PS alone but do I need to worry about the SG being almost there? Should I try and pitch more yeast? Suggestions please?

JJ

 

[Tom_S]

It depends on if you want a sweet wine or not. If I was going for a sweet wine, I'd just finish the wine at 1.002. That's not going to be a huge amount of sweetness anyway. Medium sweet wines range from 1.000 to 1.008.