First time with high acid eastern grapes

[saddlebronze]

First time with high acid eastern grapes. I am getting a pH of 3.4 and a T/A of 1.9 pct on a field blend of Marquette, Frontenac, Frontenac Blanc, etc. my Lodi stuff has been running 0.7 T/A. Should I adjust at all in the fermenter or wait until tasting.

 

[Julie]

It is easier top adjust prior to fermentation

 

[Pumpkinman]

How big is the batch of wine that you are making? How many lbs of grapes?

 

[GreginND]

1.9 seems awful high! Are you sure the TA is measured accurately? Your pH is in good shape. You have some room to reduce the acid with calcium carbonate, but I wouldn't move the pH too high. I would remeasure the TA to be sure and use a malic eating yeast like 71B or Maurivin B, plan on MLF and cold stabilize later.

 

[saddlebronze]

Maybe I am not expressing the T/A correctly. It took 19ml of .1Normal NaOH to reach endpoint on the titration. So that is either 1.9percent or 19 grams per liter unless I have my decimal wrong and it is 1.9 grams per liter. I am using 71-b and going to do MLF.

 

[lawrstin]

Because you are using .1 N solution your TA is 9.5. Which is still high but not out of this world. I agree with Greg to add calcium carbonate.

 

[ibglowin]

What was your sample size?

 

[salcoco]

your ph is correct. go forward with fermentation MLF and cold stabilize. acid will come out right, with these steps. any addition of calcium carbonate has the risk of raising the ph and making MLF difficult.

 

[GreginND]

Actually I did not recommend adding calcium carbonate. I said you could but that with that pH I would not adjust it much. Given a lower TA, I would not adjust it at this point and try to use yeast/MLF/CS to lower the acid.

Saddle, in order to calculate the TA properly we need to know how much juice you used for the sample.

If you used 10 mL, the TA is 14.2, 15 mL the TA is 9.5.

 

[ffemt128]

I have to agree with Greg, not sure I would do much with the acid at this point. Cold stabilize and use of proper yeast could solve the issue. I had some high acid PA juices last year that I took this approach with and IMHO they turned out quite nice.

 

[saddlebronze]

My sample size is 15ml. Actually I am using the titration kit from LD Carlson and it says to draw 15 ml juice, dilute with distiller water if necessary and neutralize with NaOH. Then it says each ml of NaOH is equal to .1percent T/A expressed as tartaric. Hence the confusion since 19 ml of NaOH would be 1.9pct.

 

[GreginND]

That would be true with 0.2 N NaOH. You said you used 0.1 N NaOH. I wonder if their instructions are wrong for the normality they sent you.

When in doubt, I always plug my volumes and normality into FermCalc and see what it spits out:

http://web2.airmail.net/sgross/fermcalc/fermcalc_applet.html

 

[LoveTheWine]

Does it say 0.1N on the bottle?
Those directions defiantly are for 0.2N

 

[saddlebronze]

Well, you guys are right as usual. The bottle of NaOH with the kit says 0.2N, but I used that up a long time ago and have now stocked 0.1N so my 19ml of 0.1NaOH used would equate to .95 percent or 9.5 mg/L right?

 

[GreginND]

Whew. Yes, that's right. And with that confirmation, the numbers are more in line with what would be expected. Again, I would not adjust anything chemically now. Try to reduce the malic with yeast and/or MLF and I think you'll be fine in the end.

 

[saddlebronze]

Thanks. I am pitching the MLF culture tomorrow and we will proceed along normally.

 

[LoveTheWine]

crisis averted!

 

[saddlebronze]

It's so great to have you guys as a resource especially when I am dealing with new stuff. Pitched the MLF after pressing at 1.010', tasted somewhat acidic, looking forward to MLF helping with that.

 

[lawrstin]

http://enology.umn.edu/2013/05/07/biological-reduction-of-total-acidity/

 

[GreginND]

Great. What yeast did you end up using?