I am trying to replicate Brewdog's Elvis Juice Grapefruit infused IPA. From what I understand you need to add peels of grapefruit and orange to it. Are these added during the boil or on secondary?
Can I just use Gin or Vodka to sanitize the peel or would shortly boiling the peels in water (before adding the peels and water to secondary) be better?
When rubbing or shaving citrus fruit, you realize very quickly, that the aroma you want is only contained in the very outermost layer of the skin, i.e. the zest[1]. Take care to carefully shave of this part as the pith (white stuff below the zest) can add a very bitter taste.
I have successfully used grapefruit zest in a Bock this year. I would suggest following Brewdog's advice of putting the zest directly into fermenting vessel as you would with hops when dry hopping. I assume that quite a lot of the aromatic compounds will be lost to evaporation when you boil orange zest. As with all fruit, you want to wash citrus thoroughly first to remove any pesticide, fungicide or other contaminants from the surface. Furthermore, I sanitize the zest of citrus with multiple rounds of Star San (or Isopropyl depending on what's available) to avoid any contamination with wild yeast or bacteria that tend to stick to fruit skins.
[1] Wikipedia has a good article on zest: https://en.wikipedia.org/wiki/Zest_(ingredient)
Per DIY dog instructions
Add as much grapefruit and orange peel as you dare and FV for extra citrus twist
FV = fermentation Vessel
and the tip they provide
Shave of the surface of the citrus peel to unlock the highly aromatic compounds into the beer. Avoid putting any white pith into the brew as it will create an intense and unpleasant bitterness.
Google how to Zest citrus fruit
So add it to secondary or after fermentation has completed. they dont give how much so experiment. To sanitize it, you should be able to wipe the outside of the peel with high proof alcohol, if you are following the tip.
source DIY Dog this is a very large PDF (101MB)
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