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I'm looking to brew a high gravity porter for christmas this year, aiming for OG 1.100.

I've browsed several questions on this site relating to high gravity beers and the tendency seems to be towards putting in all fermentables and yeast(s) right at the start of fermentation and just letting it crack on.

My question is, is this method more favourable over doing a secondary pitch of yeast along with a secondary addition of fermentables into the primary after an initial fermentation period?

My plan was to initially use enough fermentables to reach 6/7% ABV (FG equivalent) using US-05 at the low end of the fermentation temperature range, leave that to go for 3/4 days and take a gravity reading. Following on from that, I would add a second lot of boiled malt along with a high ABV tolerant yeast and allow that to ferment slowly over the next week or so, slowing upping the temperature until everything has fermented out. How does this sound?

  • I should add, depending on the response to my proposed method there is a follow-up question to this to do with the size of the boils for each fermentation stage. – Phizzy Aug 28 '15 at 9:06
  • I made a heavy beer basically by dumping a wort made from left-over ingredients on a huge yeast starter - the cake left in the carboy from a previous belgian blonde best (using trappist yeast). Worked like a charm. However, I made it in February aiming for Xmas - these heavy Belgian-style ales want some bottle conditioning time :-). Use a alcohol-resistant yeast and do it all at once. I'm with @wesanyer below that you don't want to dump fresh yeast in a high-alcohol environment. With a generation per 8 hours (IIRC), there is some selection pressure going on to select for alcohol resistance. – cdegroot Sep 8 '15 at 1:36
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Your best bet is to add all your fermentables at once. The reason is that if you wait until your 7% beer has completed primary fermentation to add more yeast, you are adding that alcohol tolerant yeast to a hostile environment - one in which there is already a high level of alcohol present. Despite being bred as a "alcohol tolerant" yeast, it is still yeast and still requires ideal conditions in order to kick off fermentation: good aeration, good temperature, and low alcohol concentration.

Make sure you make a healthy starter, and make sure you control your temperature - if you let it ferment at ambient, it may ferment just fine but you'll end up with some unpleasant fusel alcohols.

  • RE the ambient temperature fermentation - I thought fusel alcohols were produced at temperatures above the recommended range or there abouts? I am in the UK and I have a brewing cupboard around 16degC. I assume you were referring to ambient temp in warmer climates? – Phizzy Aug 28 '15 at 14:54
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    Yes, I was referring to warmer ambient temperatures, and you are correct, fusel alcohols occur when fermented warmer than recommended temperatures. However, which high gravity beers, the fermentation will be more active and thus produce more heat (as it is an exothermic reaction). Therefore, although your cabinet may do fine for a typical small beer, you may be surprised at the fusel alcohol content of this bigger beer. – wesanyer Aug 28 '15 at 19:37

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