Inconsistent carbonation

[dstevens]

I'm getting inconsistent carbonation. Some bottles are great; others flat.

Here's the formula:

1. Gallon glass bottles of unfiltered organic apple juice, pectic enzyme, yeast (tried EC1118, M02, S04), yeast nutrient, airlock.
2a. Either ferment 20 days, rack into gallon glass, ferment 40 days, bottle.
2b. Or ferment 30-40 days, bottle.
3. Bottle (500ml) with 2 tsp dextrose, 1 tsp lactose, 1 tsp xylitol.
4. Bottle age 30-40 days.

There's a lot of other things I've tried, like champagne method sediment disgorging , addition of apple essence, malic acid etc, but the above is the standard brewing method I use, with good results.

Starting SG is 1.050 +- 0.002, brix 11.0-13.8, pH 3.4-3.6. Fermentation typically at 68 degrees. After fermentation before bottling SG 1.000 brix 4.0

I've tried adding a touch of yeast when bottling and it did not seem to make any difference. I've also tried using yeast nutrient for more recent batches.

2 tsp of dextrose is a lot for a 500ml bottle - around 4.5 volumes depending on what my teaspoon measure is (I'll check this tonight). I'm using flip top bottles but I have no indication that the caps are leaking.

Any ideas about why the carbonation is not happening?

 

[aurora_colony_cider]

I've had this too. Even across one batch some bottles carbed, some didn't. It happened twice with Nottingham yeast. I never did figure it out.

I even popped the cap, added neutral yeast, re-capped and no joy.

Good Luck.

 

[Hankhill11]

I've had this, but not to the extreme that some were way over and others flat. My theory is that the sugars in the bottling bucket are not always 100% evenly dissolved and distributed, or some portion of higher sugar content settles as the bottling process goes on. Lately i've taken to gently siring the bottling bucket every 12 or so bottles. very gently..

 

[RPh_Guy]

Trouble-shooting I would suggest checking gravity levels on the bottle contents (after adding sugar and then later on a non-carbonated bottle) to definitively see if it is fermenting the priming sugar but the gas is escaping through the cap.

I have no experience with this but you could also try using a "bottling" yeast if that isn't what you already used. The alcohol, acidity, anaerobic environment, and low sugar/nutrients will be stressful for most yeast.

Good luck!

 

[dstevens]

Thanks for the suggestions. I add sugar to each bottle when bottling so it probably is not uneven distribution.
I will first need to remember to take my gram scales home to verify the amount of dextrose I'm adding, and then I will narrow things down by comparing SG & Brix of a good and bad bottle.
The yeast not liking the acidity, alcohol content and lack of nutrients could be the cause.

Edit: 7g of dextrose in 500ml @ 68 degrees which gives 4 volumes.

Edit2: Opened a bottle which only has slight carbonation. SG 1.010, Brix 7.2, so the sugar is still there. The cap (Grolsh style) was stuck down fairly well so I doubt it was leaking.

Edit3: Could it be the bottle sterilization killing the yeast? I use starsan, usually 0.25 oz to 1 gallon of water, swish around the bottles a couple of times over 10 minutes or so, then drain and no rinse.

Edit4: What about too small an air gap on the bottle leading to a lack of o2?

 

[dstevens]

Here's an update. The carbonation is fine as long as I let secondary go long enough. In my case, a minimum of 6 weeks is needed to get consistent carbonation. 8+ weeks is better.
As a side note, I have noticed that the brown bottles don't carb as quickly as clear bottles. Odd, because I keep the bottles in the dark.