Hop extract for post fermentation bitterness correction

I recently brewed a lighter beer, and maybe it's because I've been drinking high abv/ibu beers, but I think there is not enough bitterness in the balance.

The beer is done, and I want to add bitterness. I'm wondering if I can take a hop extract product (eg hop shot) and boil it in a small batch of water and dump that in the beer.

I have a 5g batch of beer and the keg is full so I don't want to dump more than a pint or so of hopped water into the beer. Hop extract needs to be boiled to achieve bitterness, so I figure I could boil the required amt of hop extract for the 5g batch in say 1L of water for 60m.

Question is would there be any utilization issues? For 35 IBU at 1.045, the generic guidance is 3.5mL of hop extract but for 5g.

Any ideas?

I should also state that I know I could get an already isomerized hop extract, but I was hoping to avoid that.

Not sure.


I would think that you would be better off adding isomerized extract. However, consider this:
Boiling in water will probably not create the bitter acids as it would in wort, which is more acidic. Maybe acidifying the water a bit first would be worth a shot, calculating and measuring to a target of 5-5.5 pH? Are you sure you want to dilute you beer with a liter of water, or are you going to reduce it to a cup or so during the boil?
I would try that, and then measure how much volume boiled water with extract you've got. Measure how much beer is left in your keg (ways to do this in beersmith I think using weight). Then pour a glass, and add the bitter extract in small measurable amounts, maybe 1 ml at a time. Stir and taste until the right number of drops have been added to taste. Then you could calculate how much of you concentrated boiled isomerized extract to add to your keg without going over your desired bitterness.

Let us know what happens. I've never tried this before.

Any update on this?