Hop adjustment

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MB331

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I normally follow brewing directions to the letter. My kits usually tell me to boil a specific amount (say 2.5 gallons) in order to keep the desired hop bitterness/flavor. If I were to increase the boiling amount to 4 gallons (being 60% higher than the kit's recommendation), does anyone know how much I should adjust the amount of hops to add? Is there a rule-of-thumb that for every additional 1/2 gallon or gallon you boil, there is a corresponding adjustment to hops addition?
 

BrewnWKopperKat

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Do you typically use a partial boil process (2.5 gal boil for a 5 gal batch)? Are you thking about changing the process to do a 4 gal boil for a 5 gal batch?
 
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MB331

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Yes and I have read that hops bitterness is a lot more pronounced when doing a full boil with the same amount of hops that is used in the 2.5 gallon boil.
 

BrewnWKopperKat

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I have read that hops bitterness is a lot more pronounced when doing a full boil with the same amount of hops
Do you have links to what you were reading?

eta: It is often stated that there is an upper limit to the number of IBUs that can be put in a volume of water (often 100 IBUs is mentioned). Adding 1/2 the water at the end of the boil would reduce the IBUs by half.
 
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MB331

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I don't since it was a while ago. Reading that surprised me and that is why I remember it.
 
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MB331

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I buy all my extracts from Jasper's Home Brew and they indirectly supprt this in many of their directions. Many of them tell you to boil with 2.5 gallons to extract the desired hop bitterness. Where I read about 5 gallon brews producing more bitterness I simply don't remember where I read it.
 

BrewnWKopperKat

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Do you use recipe software? If so, have you tried changing the boil volume to see if it has an impact on the estimated values?
 
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MB331

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Unfortunately no. But if any in this forum uses the software I would be very interested in the results.
 

D.B.Moody

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I think you are misunderstanding what the brew shop instructions are talking about. I think they are telling you to boil 2 1/2 gal. of water with the extract disolved in it. If you do less water, the more concentrated wort will extract less bitterness from the hops. If you boil more water, it will extract more efficiently. I think the instructions are to keep new brewers from boiling too little because they have a small pot or want to save time. You should ask your brew shop about this to see if that is the intent.
Why are you considering increasing the amount of water you're boiling? Is it to get more bitterness from the hops? If so, you should look into late addition of half of the extract. You can keep the partial boil. Remember that everything you boil has to be cooled before pitching the yeast.
 
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MB331

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It could be that I am misreading the instructions. The reason I ask is that I have an 8 gallon pot and it seems that using 1/4 of it is a waste-----boilover or no boilover. I just wanted to try a larger boil but was hesitant from what I read about hops some time ago. Just looking for confirmation that I wouldn't be messing up a $50 kit. I did email jasper's but haven't received a reply yet so I decided to pick your brains. If I do hear back I will post it here. in the meantime, thanks for the input.
 

D.B.Moody

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The reason I ask is that I have an 8 gallon pot and it seems that using 1/4 of it is a waste-----boilover or no boilover. I just wanted to try a larger boil but was hesitant from what I read about hops some time ago.
Well, you have a nice big pot, but it's not a waste to use only 1/4 of it, if that what the recipe calls for. The waste is in heating up and cooling down the extra water. Boiling more water will probably produce more bitterness. If you have brewed a particular kit before, and you think more bitterness wouldn't hurt, then you might try it just to try it.

The main reasons for partial boils (which I have done for over 25 years) are you can brew in a smaller pot on a kitchen stove and don't have so much hot wort to cool down. Since you have a big pot, and if you are not worried about how you're going to cool, you might consider not using a partial boil kit or not using a kit. Full or fuller boils will allow better hop utilization and, if you care about it, lighter color. You will probably also have less caramelizing of extract.
 
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ncbrewer

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Why are you considering increasing the amount of water you're boiling? Is it to get more bitterness from the hops? If so, you should look into late addition of half of the extract. You can keep the partial boil.
I agree with this. Late extract addition gives you the benefit of a full boil with the convenience of a partial boil. If you're looking for an especially bitter beer though, you would need the full boil since (as already pointed out) there is a limit to the IBUs - roughly 100. A partial boil would only get you up to 50 IBUs after adding the top-off water.

As far as increasing the final bitterness, you can use the Tinseth formula to see the effect of a lower gravity boil. Then you can adjust the hops to get back to the intended bitterness. This is a link: Hop Utilization Page
 
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MB331

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Yes. They really have great kits if you are interested. I think all of their extract kits are for partial boil. I guess a misread the instructions where they specify that the initial gallon size was hop related. I then projected that hop flavor would be different doing a full boil. I want to thank you and all others who have cleared this up for me. I will be sticking to the recipe instructions in the future. Again, if the company ever gets back to me I will post it here.
 
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