Bitter after taste

[maan]

Hi,

This is my 2nd batch of home made wine. I did Cab and Zinf back in 2021, which turned out pretty good.
Y'day I tasted my 2022 Merlot from one of the carboys, this is my 2nd tasting it. The first one was in early 2024. I feel like
it's turning bitter, especially the after taste. It tastes pretty good at the pallet in the beginning but the after taste is very bitter.

What could be going on ? Is there a way to fix it ?

Thanks in advance for the help.

-Maan

 

[sour_grapes]

I made a batch of Merlot a couple of years ago that was quite bitter. My suspicion (speculation?) was that I really pressed too hard and got lots of seed tannins.

I decided to just let it age and see if it softened up. You have inspired me to do more (ahem) "research" and open another bottle to see if it has improved. I will let you know the result, but not today.

But I wanted to mention that it was recommended to me to try using PVPP (Polyvinylpolypyrrolidone). This is commercially known as Polyclar (See it at Morewine: https://www.morebeer.com/products/p...L9cRUx_VwynPcjrmqmXQGqQrYrA-7INRpb3umoaxsL6Am )

I did not try this, as I decided to just try waiting.

 

[Rice_Guy]

* Yes, Seed tannins are bitter. AKA young, small chain polyphenols have bitter notes and as the plant matures these polymerize making astringent flavors and further polymerizing they drop out of solution. In crab apple I decide when to pick based on having passed through the bitter flavor notes. Tannins can also be pulled out with proteins like egg white or milk casein. One should be able to find a small protein that targets bitter or a large protein that would pick the larger astringent molecule.
* A second place where bitter shows up in flavor chemistry is that some wild lactic acid bacteria will metabolize glycerol producing bitter notes. I don’t think time can modify infection caused flavor, at least if I have an apple mixture with that it seems to stay. A wild organism which produces lactic acid should not grow if the pH is under 3.5 and is a high risk as you approach 4.0.
* another bitter goes along with reductive/ meaty/ sulfury flavor and aroma. This is low nutrient with H2S smell earlier.

Sugar is a masking agent which can balance out bitter flavor.
Flavors come in waves. Sweet for ten to fifteen seconds, Acid after that say to thirty seconds and tannins after that. You are doing good tasting to look at time, basically how fast saliva washes a compound off the taste buds.