Sour tasting wine, but not vinegar

[BMarNJ]

Last spring I made a Chilean Cab/Merlot blend with a 6 gal CabSav juice bucket and 36lbs of Merlot grapes.
Initial readings were pH3.7, sg 1.094,brix 22.5 and TA 4.5. I adjusted TA up slightly and added RC212 and yeast nutrients. I added VP41 mlf bacteria with acti-ml a day later. 5 days later sg was 1.002, pH was 3.4 and the wine tasted sour, but it was new so I wasn’t worried. Three weeks in, MLF was complete, and the wine still tasted sour.
Well, it’s almost a year into bulk aging and each time I taste it, the wine is sour tasting, like a bit of sugar would help. It isn’t vinegar and it isn’t overly astringent. It smells fruity, but it is pretty light, not a lot of mouthfeel. I don’t think I tasted the juice bucket initially, but I’m sure I tasted the grapes and they were good.
So sorry for the long post, but should I let it ride or should I test back sweetening it? It would be odd for a cab/merlot, right? It is drinkable, but not really enjoyable. My inclination is to let it age a few years.
Thanks.

 

[Chuck E]

I would "bench test" a couple things.
1. You could try glycerine to improve mouth feel and perceived sweetness. I use 10 - 20mL per gallon.
2. Back Sweeten with a simple syrup (2 parts sugar to 1 part water, simmered to clarity). I use 10 - 20 mL per gallon.
If you back sweeten you may need to add potassium sorbate to keep the yeast from re=activating.

 

[BMarNJ]

Thanks @Chuck E, right now its in a small 2 1/2 g oak barrel and a 5 g carboy, so I experiment with some portion of it.

 

[VinesnBines]

I have a red raspberry that was extremely sour, really high acid. I used calcium carbonate (four ounces for three gallons). That helped a bit. After racking off the lees, I added a couple ounces of oak chips. I actually planned to try egg white fining but when I did a bench trial with back sweetening, I decided not to bother with the fining. I'm hoping it will be half-way decent when I bottle in a couple weeks.

I also have a gallon and 1/2 of fig that is nearly vinegar. I have been oaking it to death and may end up egg white fining. I have toyed with turning the fig into a sherry or madeira. Oxygenation may improve the taste.

I finally bottled the Petit Verdot that never did taste right. It was oaked and fined with egg whites. I don't have a lot of hope for that batch.

My suggestion, keep working with your batch and don't give up.

 

[BMarNJ]

The last numbers were good, pH 3.5 and TA 7.5, so I don’t get why it tastes so sour.

 

[VinesnBines]

I ignore the numbers for the most part. I rely on my taste buds. Remember that everything affects taste, meds, food, health, O2....have you tried decanting a sample? Get someone else to taste it...sometimes we are taste blind.

 

[ibglowin]

Is it possible your numbers are off? i.e. do you trust your pH meter 100%? If your pH if off by 0.1 I could see that easily being sour to my tastebuds. I see two choices. Since it appears to not even be quite a year old yet it may be just "green" wine and needs to settle down more and integrate. The other option is a bench trial with some Potassium Carbonate to drop some acid and see if that removes the sour note. Shoot for a pH more like 3.7.

 

[BMarNJ]

It’s certainly possible that my pH meter is off, though I calibrated it prior to taking the latest measurements. I will test with a different meter.

 

[RylanJacobs]

Can we get an update on how this wine matured? I have a riesling going through a similar process. It's hot and sour right after primary. Curious to see how yours progressed.

 

[BMarNJ]

This one never really came around. @joeswine came by to taste it for me, he agreed it was pretty terrible. I chalk it up to the pandemic supply chain issue, the juice bucket was probably funky and I should have tasted it first.. On his suggestion, I added some grape concentrate to add substance and soften it a bit, and that helped some, but it is still pretty bad.