Specific gravity between .995 and 1.100 - Microcarbonation

[theTheme]

Hi all, I'm wondering if someone can help me out on a two part question (I should say that I am hoping to ultimately apply whatever I can learn to making fruit wines).

First, what wines benefit from small amounts of CO2 (without becoming carbonated)? I'm reading Emile Peynaud's Knowing and Making Wine and the author says,

"A rather high level of carbon dioxide present in certain types of white wines and even light reds, not high enough to make them fully gassy, gives them flavor and crispness. The optimal content is variable with the wine, from 300 to 600 mg/L. If it is too high the wine has a piquant taste. The same wines completely devoid of CO2 would be insipid, without shape. Yet for other types of wine, carbon dioxide is undesirable, it brings out the acid taste, reduces ambrosial flavors and accentuates the astringent and tannic hardness." (21-22)

Second, at what point do I have to worry about a standard bottle exploding (or cork popping out)? Stanley and Dorothy Anderson in Winemaking: Recipes, Equipment, and Techniques for Making Wine at Home seem to indicate that it would be at a level of 1.100 or greater,

"After fermentation has stopped and the specific gravity reading is .995 or less, you may assume that there is no reducing (fermentable) sugar left in the wine. If the original SG was above 1.100, you could be wrong and proceed to bottle an unstable wine with residual sugar. This would ferment in the bottles and blow the corks." (272)

 

[JohnT]

I don't know if I agree with her. To me, CO2 adds no real flavor to wine but the bubbles do tend to "cut" the flavor (diminish it) on the tongue.

This is a good thing if you are the type that hates dry, tannic whites.

Most winemakers take big steps to remove CO2 from wine and focus on making a white that tastes good to them.

 

[grapeman]

You must have a typo in there. Any wine would possibly explode bottles at much less than 1.100. I don't think even ice wines are finished that high. That would be a high starting specific gravity even. It certainly would make for a lot of carbonation until the bottles exploded!

 

[theTheme]

Grapeman, I went back and checked the quote, it is stated as is. I'm a little foggy on what exactly they are talking about. The quote seems to me that if you have a reading of .995 it may in fact not be completely fermented out if the starting SG was above 1.100, but I don't understand how that could be, I thought the hydrometer gave a reading of how much alcohol/sugar was in the wine at present?

Here is the Google books link pg 272

Thank you for the feedback everyone.

 

[sour_grapes]

theTheme: I just read the link you provided. Yes, I agree with your last post: the authors are referring to a wine whose original SG was above 1.100 and whose final SG is below 0.995.

What they are saying is:
If your wine final SG is below 0.995, then, in most cases, you may assume there are no fermentable sugars left.
However, there is a possible exception to this. If your original SG was above 1.100, then it is possible that there are still some fermentable sugars left even though the final SG is below 0.995. I believe the reason for that is that a wine whose original SG was as high as 1.100 will have a large ABV (alcohol by volume). Alcohol is less dense than water, and lowers the SG (whereas sugar raises it). Thus, one could imagine a solution of alcohol, water, and sugar that has a SG below 0.995.

Make sense?

 

[BernardSmith]

theTheme, Hi, I don't have an answer to your second question but I have a way of finding one.
I don't make beer but to prime beer 0.5 ounce of sugar will result in 1 volume of CO2 in 1 gallon of beer. (a volume = the space the CO2 will fill at normal air pressure and at a temperature of 68 F (I think)) - so 1 volume = 1 gallon CO2, 2 volumes = 2 gallons of CO2. Champagne bottles are designed to withstand 7 volumes of CO2 , beer bottles with caps are designed to withstand 3 volumes and soda bottles about 10 volumes. But none have corks capping the bottle.
I have never tested corks to see how many PSI they can withstand before popping but that should be a very easy test:

Simply fill a 3 single gallon carboys with water and add .5 oz of sugar to the first , 1 oz of sugar to the second and 2 oz to the third. Mix well. Number 3 wine bottles and fill each from the three carboys. Add 1 teaspoon of bread yeast to each and cork. Place the bottles in a secure area and cover with a heavy towels and wait. Two weeks and the yeast should have fully fermented the sugar in each bottle.
The amount of CO2 produced in the first will be 1 volume, in the second 2 volumes and in the third 4 volumes. If the corks don't pop then you can test at higher volumes. If the corks pop then you know that corks are not good at withstanding the pressure from specific volumes of CO2. If the bottles explode then you know that your bottles cannot withstand the pressure created by the trapped CO2.
Since 1/2 oz of sugar results in a gravity of .001 (approx) and 1 oz a gravity of .002 and 2 oz a gravity of .005 then you will know the likely probability of popped corks or exploding bottles at different volumes of CO2.

Now, in answer to your first question , a very low level of carbonation is called "petillant" (between .5 and 1.5 volumes) and petillant levels of carbonation act to increase the acidity of the wine on your tongue (compare how a glass of coke or beer tastes after you crack open a bottle to drinking a glass that you left on the table the night before. CO2 produces carbonic acid), and so, for example, I aim for low levels of carbonation when I make hard cider. I want to bring out the sharpness of the apples. I want to emphasize the acidity (like a cox's orange pippin - it is both sweet and sharp). I prefer low levels of carbonation when I make elderflower wine. I am not looking for a sparkling wine, I just want to feel something on my tongue when I taste the elderflower.
My two cents...

 

[grapeman]

I thought when reading your original post you were asking a second question about when you need to worry about a bottle exploding

"Second, at what point do I have to worry about a standard bottle exploding (or cork popping out)? Stanley and Dorothy Anderson in Winemaking: Recipes, Equipment, and Techniques for Making Wine at Home seem to indicate that it would be at a level of 1.100 or greater,"

I understand now that you were referring to a starting gravity now.

I think you would do good to begin your winemaking by making a dry wine as micro oxygenation is a more advanced subject.

 

[theTheme]

Make sense?

It does

I don't have an answer to your second question but I have a way of finding one.
...
Since 1/2 oz of sugar results in a gravity of .001 (approx) and 1 oz a gravity of .002 and 2 oz a gravity of .005 then you will know the likely probability of popped corks or exploding bottles at different volumes of CO2.

I will definitely be trying this. I don't have any 3 gal carboys yet, but I love a good experiment. I wonder if #8 vs #9 corks would make a large difference is held pressure?

a very low level of carbonation is called "petillant" (between .5 and 1.5 volumes) and petillant levels of carbonation act to increase the acidity of the wine on your tongue

This is great information, thank you! It's amazing how just knowing the right way to call things can make a huge difference when you are looking for information. I prefer a little bit of fizz in my drinks, but generally find champagne bubbles to be too much. I'm looking forward to experimenting with petillant in my fruit wines.

I think you would do good to begin your winemaking by making a dry wine as micro oxygenation is a more advanced subject.

This is very likely true. And, my first batch just went into the bucket! Waiting 24 hrs before the yeast goes in.