Laymans view on fermentation

[sampvt]

I am sure there are many people on here with as much limited knowledge of winemaking as I have and there are the experts as well. I am trying to learn as I go along and one thing struck me yesterday after reading up on the subject.

Every yeast has an avenue of working temp. some yeasts operate best between 21 to 27 degrees Celsius and there are some that ferment lower or higher than these parameters.

I have a 30 day expensive Kenridge kit on at the moment and it fermented out in 6 days to a slow gloop in the airlock and achieved an SG of 990 on the 7th day. The kits says rack off at 1010 (which mine achieved after 4 days) then leave for 12 more days to ferment out.

I was told by Kenridge to stabilise it at 990 and clear it as it had finished. I posted a picture of the 990 reading on another post but my point here is that if the sg has reached 990, surely the yeast has done its job and eaten all the sugar and achieved an alcoholic rating which lives in the acceptable range for my wine.

In closing....... if the temp which I had mine on (27 degrees Celsius) was too high as many have said, it would not have worked properly and the sg would not have dropped, ergo if the sg is reading 990 which is dry and fermentation over, why should I be worried. That batch was put on first on the 11th of march and it is now nearly clear and ready for bottling. This means that Kenridges 30 day assessment is flawed as my brew will be bottled on Monday the 23rd, making it a 12 day wine not 30.

Can any of the experts on here see any flaws with my logic because as a layman, I cant see where the problems might crop up. If we brew by Hydrometer and not eyesight, surely these kits guidelines are at best only a guide and this kit might be better brewed at a higher temp.

 

[dralarms]

From my experience, fermenting too warm causes off flavor issues. If the yeast is too warm it works too fast (therefore 12 day fermentation vs 30 day kit). My first year making wine I had my stuff in a room that was too warm, yes I was making wine very fast, and it affected the flavors.

My suggestion is to find a different place to ferment or if you used external equipment to raise temperature you need to get something that does not raise the temperature that much.

 

[Arne]

dralarms has a good suggestion. But, one of the great things about making your own wines is you can make them however you like them. If you like the taste when they ferment fast, ferment them that way. If you like them with a slow ferment you can ferment them that way. All the recipes you find are just a guide. Most have ingredients that will change with the batch. Ripeness of the fruit or lack thereof, sweeteness of the same, acidity in the batch. It is up to you to help control that. Make em how you like them and life it good. Good luck with yours, Arne.

 

[grapeman]

First of all the wine will not be "done" by Monday. It may look clear and yes you could bottle it, but it will continue to drop some fine sediment for a while. I would wait at least the 30 days before bottling it being sure the carboy/demijohn is full.

As far as fermentation, yes slightly higher temps will speed it up. You are referring to a Gewurztraminer kit from Kenridge if I am correct. That is a nice spicey highly aromatic wine. When you ferment too quickly the yeast are very active and can actually "blow off" the aromatic esters, decreasing your aromatic character of the wine. It will still be very drinkable and will retain some of it's character but it will lose a lot. Don't strive for this in whites. The general rule with those is "low and slow" meaning ferment at a bit cooler temps and let it progress slowly.

 

[DoctorCAD]

Dont bottle for 6 months...Your taste buds will thank you.

 

[Floandgary]

"NO WINE BEFORE ITS TIME" All we need to do is learn how to interpret and use the data our instruments provide. In addition and more-so is the knowledge you can get from this great gathering of winemakers who have gone down the "what about?" path. True, most instructions are simply guidelines meant to keep you in the ballpark. What you can learn here will keep you on the playing field!! Primary in this game is PATIENCE

 

[BernardSmith]

I am sure there are many people on here with as much limited knowledge of winemaking as I have and there are the experts as well. I am trying to learn as I go along and one thing struck me yesterday after reading up on the subject.

Every yeast has an avenue of working temp. some yeasts operate best between 21 to 27 degrees Celsius and there are some that ferment lower or higher than these parameters.

I have a 30 day expensive Kenridge kit on at the moment and it fermented out in 6 days to a slow gloop in the airlock and achieved an SG of 990 on the 7th day. The kits says rack off at 1010 (which mine achieved after 4 days) then leave for 12 more days to ferment out.

I was told by Kenridge to stabilise it at 990 and clear it as it had finished. I posted a picture of the 990 reading on another post but my point here is that if the sg has reached 990, surely the yeast has done its job and eaten all the sugar and achieved an alcoholic rating which lives in the acceptable range for my wine.

In closing....... if the temp which I had mine on (27 degrees Celsius) was too high as many have said, it would not have worked properly and the sg would not have dropped, ergo if the sg is reading 990 which is dry and fermentation over, why should I be worried. That batch was put on first on the 11th of march and it is now nearly clear and ready for bottling. This means that Kenridges 30 day assessment is flawed as my brew will be bottled on Monday the 23rd, making it a 12 day wine not 30.

Can any of the experts on here see any flaws with my logic because as a layman, I cant see where the problems might crop up. If we brew by Hydrometer and not eyesight, surely these kits guidelines are at best only a guide and this kit might be better brewed at a higher temp.

I am not an expert and I don't make kits... but I think the temperature range for yeast has a great deal to do with the kinds of alcohols that the yeast will produce. At different temperatures the same yeast will ferment the same sugars to produce very different combinations of different but similar alcohols. Some of these are going to add pleasant complexities to your wine and some will produce reactions on your tongue that you may find less pleasant. Even if these are produced, as the wine ages I think they are modified by the yeasts and by other chemical reactions that are taking place in the background over weeks and months... and sometimes years... Wine is an organic product and as such is dynamic and undergoes changes as it ages.
All that said, I think that most experienced wine makers aim for the lowest viable temperatures their chosen yeast prefers and they aim for a slow and steady fermentation.

 

[wineinmd]

I'm coming from the beer brewing world and fermentation temperature control is very important since the yeasts used can contribute a wide range of desirable, or undesirable, byproducts, depending on the temperature range. Fermenting too warm can lead to a wide range of off-flavors in the finished product. I'm just on my first batch of wine, but started to do a little digging to see if wine yeast are similar. Here is a high-level article that talks about wine fermentation temperatures in a general sense.

As mentioned above, it sounds like the higher temperature yours fermented at likely caused the loss of aromatics. Here is a snippet from the article..

The type of wine you are producing will direct what temperature range is optimum. White wines are generally fermented under cool (not cold) conditions, while red wines can be fermented a little warmer. For a fruity, white wine, cooler temperatures — 40° to 70° F — allow for the retention of highly volatile aroma components. A rapid, warm fermentation will create a draft of carbon dioxide rising from the must, taking fruity esters with it. However, red wines stand up much better to elevated temperatures (50° to 80° F), and extraction of color and tannins may actually be enhanced by it.

The biggest lesson I learned from brewing is that time is your friend. It's hard to do in practice, especially at the beginning, but will pay off in the long run.

 

[fabrictodyefor]

Just wanted to pop in here and say this was a great "lesson" thread. I often just read through threads, old and new to glean knowledge. I love it when someone else poses a thought that supplies me with information I didn't even know I wanted!

 

[wineinmd]

Also note that the discussion of fermentation temperature in the brewing world has really picked up steam in the last several years. Many homebrewers now cite temperature control as one of the most important considerations when producing a quality product.

Because of this, I was very surprised to see that the article I linked was from 1999. I've seen subsequent articles from the same magazine give contradicting information, especially a 2008 article penned by Tim Vandergrift that suggests that fermentation should be done at the upper end of a yeast's range, although that article barely touches on the differences between the temperature ranges for whites vs. reds. He also supports his thoughts with rather odd considerations like the retention of CO2, which can be tackled by raising the temperature after fermentation is complete or nearly complete, and the wait required for a cooler fermentation to finish. Is the end goal a speedy process or a higher quality wine?

I haven't found much information regarding which compounds are released at different temperatures and what the resultant effect those compounds have on the finished product. Perhaps those byproducts are not as big of a factor in winemaking as they are in brewing, but I would be interested in reading some of the science behind it.

 

[wineinmd]

Curiosity got the best of me so I started looking at research papers. There seems to be quite a bit of evidence to support the idea that lower fermentation temperatures result in a wine with enhanced aroma retention and a decrease in unpleasant compounds. Most of them compared temperatures around 13-15C and 25C.

From the conclusion section of a May 2006 study by the Federation of European Microbiological Societies....

Previous studies from our research group (Torija et al., 2003; Llaurado et al., 2004) showed that fermentations carried out at lower temperatures (13C) improved certain sensory attributes of the wines that are related not only to primary aroma retention, but also to an increase in the biosynthesis of flavour-active compounds, such as acetates and ethyl esters, and to a decrease in unpleasant ones, such as acetic acid and fusel alcohols.

 

[heatherd]

I think fermentation - like everything else with winemaking - has numerous variables. Type of yeast, temperature of fermentation, stirring or not, yeast nutrient, etc. You can certainly expedite the process but you might sacrifice something. On the other hand, it's tough to know what's missing when you haven't made the same wine more than once to taste the difference between fast and slow.
Heather

 

[JohnT]

Just to weigh in here..

Temp DEFINTELY affects the flavor of wine.

If you are trying for a traditional gewürztraminer, and ferment it "hot", you will burn off the fruit characteristics of the wine.

Now, before anybody pounces on me, I know that this is not a technical description but it does accurately describe the result on the pallet.

Gewürztraminer (and Riesling for that matter) are traditionally fermented very low and very slow over a period of weeks and not days. Believe me, I know from experience that you can not achieve that crisp, fruity, clean taste of German wines unless you go low and slow!

 

[wineinmd]

Burning off is essentially what is happening. Some of those fruity compounds are volatilized at higher temperatures, which drives them and their associated flavors off. I wasn't able to find a study that tried to identify at what temperature that started to occur, probably because there are so many other variables involved, but it was fairly clear that for wines fermented at 25C, those desirable compounds were much lower in concentration than in those wines fermented in the 13-15C range.