Bottle Conditioning Curves

[tomakana]

Wasn't sure whether this is best in the fermentation, bottling, or cider forums, but I'll take a stab here first since it relates to bottle conditioning. I know some of this question depends on the health of the yeast in question, but for the sake of argument, assuming the yeast populations are as close to identical across vessels as possible for this...

So, picture bottling cider from the same batch into two 12-oz bottles with priming sugar added to each bottle directly. Assuming that there is the same amount of yeast in solution and the same amount of sugar in each bottle (using an ideal case), should the rate of consumption (therefore the rate of carbonation) be the same in both bottles? In other words, will the sugars be completely consumed at close to the same time? (My instinct is yes, with some variation given that these are living organisms, so won't be completely consistent - but the variation in time should be relatively small, all other things being equal)

What if there's the same amount of yeast, but different amounts of sugar - will the yeast consume the sugars at the same rate in each bottle, meaning that when the first bottle's sugars are fully consumed there is still some left in the second bottle? Or, does the presence of more consumable sugar increase the rate of fermentation in bottle 2? (My instinct says that the fermentation speed is specific to the yeast and they shouldn't eat faster just because there's more food, but I'm not sure).

What I'm trying to figure out is whether I can use this process to test the level of back-sweetening I like in my cider by varying the amount of juice I sweeten with before I bottle. I'm planning to let it carb, then pasteurize to keep some sweetness. So what I'm thinking is to dose the bottles with three different amounts of juice (I know the sugar content, so can get a good idea of how much sugar I'm adding), let them condition for the same length of time, then when I pasteurize they should all be similarly carbed, but have different levels of sweetness. Depending on which ones are preferred, I know in the future how much to back sweeten with at the batch level, at least generally speaking.

That really depends on my assumption that the bottles will all have their sugars consumed at roughly the same rate - if that's not the case, then I'll have really different carb levels and no real read on the sweetness. I know that I sometimes get different carb levels in my bottles of beer, but I think I've narrowed that down to poorly mixed priming sugar in the bottling bucket - when I use carb drops, the problem goes away.

 

[jseyfert3]

I can't answer your original question, but several members here have attached pressure gauges to bottles to know when a batch is ready to pasturize. They typically use one bottle per batch, but you could use three bottles with pressure gauges and then you'd know it was the same amount of carbonation in all the bottles.

 

[Vale71]

The theory says that higher concentrations of simple sugars will increase the yeast's metabolic rate, all other parameters being equal, as simple sugars are absorbed through diffusion across the membrane and the diffusion rate is proportional to the concentration of the sugar (or, more precisely, the concentration differential between opposite sides of the membrane). But it's really hard to tell without some actual trials whether the difference will be significant enough to enable you to actually do what you intend to do.

 

[tomakana]

Cool - thanks, both. Going to do a couple of experiments, I think. If I get anything I think is useful, I'll post back.

 

[SiblingCider]

Tomakana: Still in primary, but I'm doing pretty much the same thing you are. Dosing individual bottles at three different levels and using a pressure test rig (the "Maylar" rig you can find in these forums). I'm only monitoring the dry (carbonation only) and sweetest formula for this one.

Haven't gone through it word-for-word, but I found this article useful. I believe it answers the questions you're asking. Wasn't brewing-specific, but may very well apply.

(leak testing using soda)

 

[doug293cz]

...
Haven't gone through it word-for-word, but I found this article useful. I believe it answers the questions you're asking. Wasn't brewing-specific, but may very well apply.
...

Interesting article. A couple of things that could have been mentioned but weren't:

1. They noted that glucose produced significantly less CO2 (lower wt. loss) than either fructose or sucrose. There is a good reason for this - glucose is highly hydroscopic (just like maltose or DME), and will clump up as it absorbs moisture from the atmosphere. For this reason, almost all glucose (dextrose) sold is glucose monohydrate. Glucose has a molecular wt. of 180.156 g/mol, and glucose monohydrate has a molecular wt. of 198.17 g/mol. Thus: 20 g of glucose monohydrate contains only 20 * 180.156 / 198.17 = 18.18 g of pure glucose. So, almost 10% less CO2 is produced by equal amounts of glucose monohydrate vs. equal amounts of either fructose or sucrose.
2. They also noted that sucrose tended to produce very slightly more CO2 than did fructose. This is also as it should be. Sucrose has a molecular wt. of 342.30 g/mol, whereas fructose has a molecular wt. of 180.156 g/mol. One sucrose produces 4 CO2 (molecular wt. of 44.01), so 20 g of sucrose produces 20 * (4 * 44.01) / 342.30 = 10.286 g of CO2. One fructose produces two CO2, so 20 g of fructose produces 20 * (2 * 44.01) / 180.156 = 9.77 g of CO2. Both cases assume the yeast consumes 100% of the available sugar.

Brew on

 

[SiblingCider]

Here goes nothing! One dosed for a dry 2.5 volumes and the other with more for residual sweetness. Curious to see if one carbonates faster. Burped them a while after bottling because they came up to room temp; good 8-10psi added from fridge temp to 65F or so.