Bottle Conditioning Conundrum - What Happened?

[ElBarbudo]

I'm a little baffled, here's the situation:

I was messing around and decided to ferment a half-gallon each of apple cider, POM pomegranate juice, and cherry juice. I boiled each one briefly (I would later find out you're not supposed to boil apple cider. Oops), cooled them, pitched 2g of champagne yeast, and let them all ferment around 70F for about 2 weeks (they had all completely stopped bubbling at this point). I then bottled them into 16 ounce flip-top bottles, each one with 1/8 ounce of table sugar and let them condition in the same box for 2-ish weeks around 70F. So here's the thing: when I opened them after this period, the cherry juice bottles were all perfectly carbonated and delicious. The cider and the pomegranate juice, however, were super flat and didn't so much as hiss when I opened the bottles.

So my question is: how could this be? All the variables were pretty much the same, except for the type of juice. A few of my guesses: 1) the original juices had different sugar contents, possibly with the cherry juice being the lowest, and the ABV after the initial fermentation was too high in the other two for the yeast to "wake back up". Is that kind of thing ever a concern? 2) The juices that ended up flat both had preservatives in them that weren't in the cherry juice, preventing the yeast from "waking back up" (I know the cider probably did, but I don't think the pomegranate juice did) 3) There's some other property of the different juices that caused this.

Thoughts?

 

[BrewInspector]

Leaky flip tops?

 

[ElBarbudo]

Leaky flip tops?

That was my initial thought as well, but it seems unlikely that it would just so happen to be two of the same kind that worked. Plus, I've used these for carbonation before and haven't had any problems

 

[BrewInspector]

I don't know if preservatives would have had any affect on carbonation. You mentioned higher ABV in the failed bottles, how high? Doubt that would prevent carbonation in this case but if high enough it might have slowed progress.

Two weeks is not always enough. (Usually not sufficient carbonation for me) I would move their temp up to a low / mid 70s for another week or two before thinking that they are not going to carbonated on their own.

Being flip tops it would be easy to add additional yeast if more time and warmth don't do the trick but I would wait and see.