Forgot to heat fruit, delayed fermentation question

[Supabrew]

I have a nice stout going on and thought it could use a little fruit flavor and a slight FG boost so I added a 2 pound bag of figs from Costco. It was in the primary for 5 weeks before adding the figs.

I used a food processor to chop up the figs very finely along with about a cup of the stout pulled from a sanitary sampler (SSBrewtech conical). I froze the lot for a few nights, thawed, then froze again and thawed.

Unfortunately, I was so focused on keeping oxygen out of the fermenter when I opened the lid to add the fruit (by pumping in CO2 through the blow-off cane) that I totally forgot to heat up the fruit to around 160F for 10-15 min...!

So I added un-heated figs, albeit finely chopped up ones and rocked the fermenter back and forth to rouse the yeast. Of course there was no activity at all for about a week. Then, suddenly, there was a semi-vigorous fermentation for about 1.5 days. I have not yet checked with a hydrometer since it is still fermenting, though it is slowing down.

So why such a huge delay in the fruit fermentation here? Just wondering so I can learn from the experience.

Also, any issue with not heating the fruit up? The stout is >8% ABV so I am assuming (hoping) that the alcohol will kill any baddies that happened to go into the beer. Am I just getting less accessible sugar for the yeast to feed on?

 

[myndflyte]

As far as I know, heating the fruit doesn't release sugar, it just pasteurizes it. My guess is that the delay was just because it had been 5 weeks in the primary. The yeast probably did most of their work in the 1st week and they've just been sitting there for a few weeks. It probably just took them a little time to wake up and get to work again.

As for not heating it, people have pretty good results with adding frozen fruit to beer so you should be fine.

 

[sborz22]

a) you probably won’t boost the booze because the fruit also contains significant water content. Some fruits will actually lower the abv.

b) frozen fruit is great for breaking down the fruit walls and making more sugars available. I brew a BW regularly with raspberries and I always use frozen.

c) I second @Supabrew and the fact that it was sitting that long in primary most of the yeast had settled.

d) please update us on the fig taste. I am very curious.