Malbec problems

[KayThrasher]

We (wine making club) ordered 1 ton of Malbec this year for the first time. Had been told that Malbec doesn't travel well but found a vineyard that had some extra to ship to us. The Brix was 20 and the grapes very juicy. The juice didn't have much flavor, but we've been told that Malbec takes a while to develop. During primary fermentation, the Malbec never tasted right; one of the 2 bins was significantly worse tasting. It just had an off taste. Continued on with fermentation and pressed and put the wine into a stainless steel tank to await distribution to the club members. During fermentation, the juice flavor improved a little, but not much.

Saturday, we distributed the Malbec - there was a significant odor (maybe sulfur, maybe dirt?) but the group thought that maybe aging it would improve it. The flavor is ok, but not great. My question - is there anything that we might be able to do to improve the flavor/aroma or do we just wait and see? The club has about 60 gallons in an oak barrel, and the rest was distributed into carboys.

This is my first year as 'chemistry wizard' and the Zinfandel and Cab Sav seem to be turning out ok, just the Malbec is off. Any advice would be greatly appreciated!

 

[Smok1]

Any other info, Ph and ta? 20 brix seems quite low to me for a malbec, possibly under ripe? H2s smell could be lack of nutrients in the must, what yeast did you use? Nutrients?

 

[KayThrasher]

No info on Ph or ta - the yeast used was Melody from Gussmer. Did not add additional nutrients because we've been having problems with fermentation getting so hot we have had to add dry ice. The Cabernet Sauvignon which came in at the same time (and with similar Brix reading) turned out fine using the same yeast and no additional nutrients.

 

[Smok1]

No info on Ph or ta - the yeast used was Melody from Gussmer. Did not add additional nutrients because we've been having problems with fermentation getting so hot we have had to add dry ice. The Cabernet Sauvignon which came in at the same time (and with similar Brix reading) turned out fine using the same yeast and no additional nutrients.

How hot did the must get? Seems this yeast strain is not very tolerant of heat at all, 25c max before it starts killing itself off and would most likely add to h2s smells and off tastes. Did the fermentation complete? Below 1.000sg?

 

[KayThrasher]

Actually, it was the Zin that we had processed a couple of weeks before that got so hot (used Merit yeast for that). The Zin went from 69 degrees to 87 degrees in 3 days before we added dry ice. Last year we had the same issue with our Zin, same time frame with temps from 60 degrees to 93. My speculation is that these grapes were early shipments and that even though we have some space conditioning, the outside temperature here in East Tennessee contributed to the fast fermentation and high temperature of the must. Shipments received later in the year (both this year and last) fermented much more slowly and did not reach high temperatures.

The fermentation of the Malbec did complete before pressing.

Thanks for the comments!

 

[antont]

Looks like hydrogen sulfide smell - rotten egg, rubber, or similar. It was 2013 and I was fermenting malbec grapes from Chile. During the primary fermentation a strong odor, as above, developed and was to be felt abundantly around the fermenter. Several days after pressing the smell was still there and I was very worried and started looking for possible solutions. Two seemed possible (without the use of chemicals):

1. Splash the wine over a copper surface
2. Aeration

I did the aearation. Poured the wine in 5 gal bucket and from there poured into another. Repeated several times until I could not feel the odor. (I had added a 1/8 tsp of potassium metabisulfites per 5 gallons)

Put the wine back into carboys. Initially the wine smelled clean but after 2-3 month I felt a bit of smell again. Repeated the above but it took less bucket pouring to get rid of the smell. Several months later (10 maybe) there was no smell developed. I bottled. I opened the last bottle in Jan 2017 and it was clean with the typical varietal flavors and rather balanced. Not as impressive as the 2011 or 2012 Malbec but still very pleasant.

Since then whenever I feel a bot of hydrogen sulfite smell I do the aeration and works well.

 

[JohnT]

Gussmer has a wine lab. You could send them a sample and have it analyzed.

 

[Stressbaby]

Looks like hydrogen sulfide smell - rotten egg, rubber, or similar. It was 2013 and I was fermenting malbec grapes from Chile. During the primary fermentation a strong odor, as above, developed and was to be felt abundantly around the fermenter. Several days after pressing the smell was still there and I was very worried and started looking for possible solutions. Two seemed possible (without the use of chemicals):



1. Splash the wine over a copper surface

2. Aeration



I did the aearation. Poured the wine in 5 gal bucket and from there poured into another. Repeated several times until I could not feel the odor. (I had added a 1/8 tsp of potassium metabisulfites per 5 gallons)



Put the wine back into carboys. Initially the wine smelled clean but after 2-3 month I felt a bit of smell again. Repeated the above but it took less bucket pouring to get rid of the smell. Several months later (10 maybe) there was no smell developed. I bottled. I opened the last bottle in Jan 2017 and it was clean with the typical varietal flavors and rather balanced. Not as impressive as the 2011 or 2012 Malbec but still very pleasant.



Since then whenever I feel a bot of hydrogen sulfite smell I do the aeration and works well.

This is what I was thinking. Sounds like the wine got "reductive." You could splash rack one carboy and see if it goes away. Reduless might be another option.

 

[Stressbaby]

One more thought. Noblesse is said to "clean up" different types of off odors, that might be another option.

 

[KayThrasher]

Great idea, thanks! I'll check with Gussmer about lab testing.

 

[user 36973]

Yeast often get stressed and produce H2S when the fermentation temp gets too high. They also can produce H2S at the end of fermentation as they struggle to complete the fermentation, in which case you can add additional yeast nutrient proactively when 2/3 of the sugar is consumed.

To resolve the H2S issue use copper sulfate. You may want to pull off a glass worth of the wine for a bench trial, put a few drops of the solution into it and make sure that the offensive odor is eliminated before dosing the batch of wine. For a 10% concentration solution then use 1ml for each 80L of wine (yields 0.5ppm copper). Stir it gently in and check the next day for the odor. Keep repeating until it is gone. This process reduces the chances of adding too much in. Copper sulfate is much more controlled than splashing and oxidizing your wine.

 

[sdelli]

Not to sure you will ever get this wine to be what you want now.
But next time make the adjustments quickly!
Lots of air.... blow a fan into the must. Add nutrients and dap.
Make it go away...
Like being a cook in the kitchen and your food is burning or has no flavor. But you continue to finish cooking it that way and try to fix it on the dinner table.

 

[ceeaton]

Like being a cook in the kitchen and your food is burning or has no flavor. But you continue to finish cooking it that way and try to fix it on the dinner table.

I agree. You can't fix it once it is done, especially if it is way off.

That 20 brix to start with bothers me a bit. Some of our "Northeast" grapes end up that way, but a Malbec should be picked at a much higher brix. I can imagine that picking 20 brix would lead to underdeveloped flavor for the variety, and nothing that they yeast does during fermentation is going to help improve that much.