Critical look at each other's wine

[TXWineDuo]

I would think that your 1 Gal frozen ice jugs would last longer being a bigger block of ice, maybe?
When our primary gets down to 75 degrees and the brew belt is not kicking on and I grab the melted 2 liter ice bottles out of the water my hand gets cold!
So for another test in 2 phases 1) how long does the initial 2-ice bottles take to thaw and 2) once temperature for primary is achieved how long does the next 2-ice bottles take to thaw to know how often you have to change the ice bottles.

TXWineDuo

Here a video shows a block of ice takes longer to melt in chilled water.
https://youtu.be/FzxPYc8I__Q

 

[cgallamo]

Bringing this thread back up because I believe heat and nutrients are not always the issue.

I have had issues with H2S in about %60-%70 of my grape wine ferments (fresh and frozen pails seem the same), and zero with other fruits. I thought it was heat in the past, but this last time that does not explain it - they never rose above high 70s (maybe touched low 80s) and it was a long slow ferment.

This time I had three batches going of frozen pail blends and had issues in 2 of the 3. I used yeasts that claim to have few problems with H2S (AMH, Rockpile, and BDX), followed the re-hydration procedure, and yeast nutrient schedule (even added %10-%20 more). H2S started to appear as soon as fermentation got underway in earnest maybe three days after pitching, and would blow off with stirring/punchdowns. The only difference (other than yeast) in the management of the batches was the size of the fermentation bin (the smaller ones had the issue), and the specific gravity when first racked (one that was racked earlier had greater issues probably because it took longer to ferment).

So what else could be the issue? The use of sulfur as a fungicide or other agricultural management technique? What are some other techniques we could try in winemaking process to reduce the production of H2S?

Using a yeast that does not produce H2S may be simpler, but what if it does not provide the flavor profile you are looking for? Also treating with copper is potentially problematic. I read somewhere (I think in the redulees documentation) that getting these compounds is not all bad, there are other similar compounds that provide spice, leather, smoke elements that are desirable in the wine, and treating it with copper may reduce or eliminate these as well.

 

[sour_grapes]

So what else could be the issue? The use of sulfur as a fungicide or other agricultural management technique? What are some other techniques we could try in winemaking process to reduce the production of H2S?

It is possible for sulfur-containing fungicides to be converted to H2S (without going through yeast. My understanding, however, is that every vineyard knows this, and so avoids using sulfur-based compounds close to harvest time. ( http://www.ajevonline.org/content/44/2/211 ).

In most cases, it appears that the principal pathway to H2S production is by the metabolic pathway of yeast that are nitrogen starved. See:

https://www.practicalwinery.com/novdec05/novdec05p26.htm

http://aem.asm.org/content/61/2/461.full.pdf

http://search.proquest.com/docview/852549041/abstract

Here is my layman's description of the process as I understand it:

First of all, yeast autolysis is real, but the key word fragment there is auto-. The way it works is that, for whatever reason, a yeast cell dies. Then the enzymes in the now-dead cell begin to break down that cell. It is not the case that starved, zombie yeast cells start eating the brains of other yeast cells. However, John is correct: if yeast autolysis (especially of a large amount of sediment) is allowed to proceed for a long time, then sulfur compounds may be liberated. But this is different from the H2S produced during an active fermentation.

From my reading of the primary and secondary literature, this is my understanding of H2S production and its relation to N deficiency. Proteins are made of amino acids, and two important amino acids contain sulfur. The yeast has to provide the sulfur to form these compounds to the proper organelle during protein synthesis. It does so in the form of H2S, which it extracts from more complex sulfur-containing compounds. One organelle passes the H2S off to the organelle responsible for protein synthesis.

However, nitrogen is a major component of amino acids (hence the root amine, from ammonia.) If there is a dearth of N, the organelle responsible for synthesizing the sulfur-containing amino acid cannot do its job; this results in a surfeit of H2S, which the yeast then excretes.

As John points out, we are extraordinarily sensitive to H2S and thiols (larger SH-containing molecules). That is why they add a tiny (ppm) amount of methane thiol to your natural gas supply, so that you can smell when you have a gas leak. This is good for gas-leak detection, but the unfortunate result for winemaking is that we cannot tolerate very much H2S excretion by our pet yeasts.

 

[jswordy]

Well, I'm glad this was brought back because I really enjoyed reading it!

Going back to the fermentation cooling, another possibility that's used in beer making is evaporative cooling (the swamp cooler effect), and it would work particularly well in dry climes. It is amazing how cool a fermenter surrounded by continually wet fabric with a fan on it will get.

Beer guys use XXL tee shirts stretched over their brew buckets, with a tail submerged in a water bucket to keep the shirt wet. I could envision something made from cheap towels and sewn to make a zip-able or button-able jacket for almost any size fermenter. After use, squeeze out and toss it in the washing machine to make it ready for next time.

Just an errant thought, offered FWIW.

 

[NorCal]

Well, I'm glad this was brought back because I really enjoyed reading it!

Going back to the fermentation cooling, another possibility that's used in beer making is evaporative cooling (the swamp cooler effect), and it would work particularly well in dry climes. It is amazing how cool a fermenter surrounded by continually wet fabric with a fan on it will get.

Beer guys use XXL tee shirts stretched over their brew buckets, with a tail submerged in a water bucket to keep the shirt wet. I could envision something made from cheap towels and sewn to make a zip-able or button-able jacket for almost any size fermenter. After use, squeeze out and toss it in the washing machine to make it ready for next time.

Just an errant thought, offered FWIW.

We have 3 ferments planned. 2 ton, 1 ton, .5 ton. On this scale, it's hard to scale solutions that work on 5 gallon levels. I ended up not doing anything, so we will go with good ferment temp monitoring, have ice jugs ready and dry ice for emergencies.

 

[jswordy]

We have 3 ferments planned. 2 ton, 1 ton, .5 ton. On this scale, it's hard to scale solutions that work on 5 gallon levels. I ended up not doing anything, so we will go with good ferment temp monitoring, have ice jugs ready and dry ice for emergencies.

I make 20 gallons at a time. You guys are at winery levels of production.

FWIW, a second possibility is to obtain a new car radiator (large sizes of which can be bought for $300) or a large sized replacement part air conditioner condenser coil and connect it in series with a pump, thermostat and an immersion cooler coil. Use water as your coolant, and run a high speed fan through the radiator or condenser coil. The temp differentials produced in a/c systems and auto engines make this an attractive adaptation.

You might even get more cooling effect if you set the condenser coil in a pan of water and use a small pump to also spray water from the pan on the side of the coil that the fan is on (again the swamp cooler effect, similar to a/c systems used on large buildings).

All of that would be relatively easy to assemble from online purchases and simple to construct and use.

Even at my 20-gallon level, I'm really aware of how high the temps can get once yeast get going, and I am exploring viable fixes myself.