Ridiculous low PH

[David Engel]

Hi All,
Second year attempt with Merlot. Starting out just like it did last year… brix of only 18 off the vine. They had to be harvested, swelling due to the rain and some already turning to raisins. Corrected with sugar to get a brix of 23 and sg of .96. Used my PMoYoko ph meter (yea it’s a beginner cheepy), did a successful calibration and read 2.5. Then tried two more times and the ph just nosed dived to 2.5 both times. Good brix and sg… what makes the ph so stupid low from these Merlot grapes?

The good woman says “maybe God is trying to tell you something. 🤣😖

Dave

 

[cmason1957]

Did a taste of the juice give a huge pucker factor when you drank it. A pH of 2.5 would probably not taste very good. My guess is that the pH meter is off. Even though it calibrated fine.

 

[jimkinney]

I haven't worked with Merlot but at 18 Brix I would not be surprised to find a low ph. Even though you had some raisins it sounds like your grapes are under ripe. The ph would raise as the grapes continue to ripen. I grow grenache and syrah and my grapes are just coming out of verasion by the time they hit 18 brix.

 

[Rice_Guy]

I agree with Jim. As a cross check / coming out of industry I would compare the meter with off the shelf liquids. ex Mountain Dew pH 2.82; Pepsi flat pH 2.49, W CO2 2.49, Coke flat pH 2.86, W CO2 2.81; Franks sour kraut pH 3.29. . . . . . We have food safety rules which are based on pH so things you keep on the shelf should be close (~ 0.1 unit) year after year.

If the juice has low TA it can taste OK. If high it will make you spit. ex distilled vinegar pH 2.53 with TA of 6.0%. vs. flat 7Up pH 3.51 with TA 0.15% and 7Up W CO2 pH 3.48 with TA 0.39%.

 

[David Engel]

Hey All,

Update. I’m comparing my lab notes from last year. I started with a little higher brix, and I got the ph up. I used calcium carbonate, got the ph up to 3.55 and fermentation is coming along nicely, the smell is noticeably different than last year, the color is darker, however the taste is still on the tart side. Anything I can do? This is the last year for these, ines are coming out of the ground this winter and being replaced with Pinot Noir Precose.

 

[Rice_Guy]

With northern hybrids we chill to 28 or 29F to pull out bitartrate. We run MLF or use 71B to reduce malic acid.

I wonder if you should plant petite pearl? The tannins are pretty good.