leaf hop absorption affect boil off?

[jmancuso]

I haven't been brewing long but I have been brewing frequently and have been pretty precise with my efficiency, boil off,etc. I have been formulating my recipes for 11 gallons and always boil off around 2.75-3 gallons. So starting with a 14 gallon boil i put 5.5 gallons in each fermenter. Tonight was my first IPA using all leaf hops, i figured the hops would absorb some wort so i started with a 14.75 gallon boil. I was shooting for an OG of 1.061 and my preboil reading was 1.053 which was a little high but close(90 min boil). Towards the end of the boil the level was right about where it usually is, but when I siphoned it into the fermenters it was not even close. Instead of ending up with 11 gallons of 1.061 wort I ended up with 8 gallon of 1.072 wort. Does the absorption from the hops also affect evaporation? If i use this many hops again should i collect an extra 3 gallons of sparge running?
Thanks, James

 

[Justibone]

Did you just top off to get to 11 gal.? If so, what was your gravity after that?

 

[Northcalais40]

water absorption by the hops can not affect the evaporation rate. I don't know how much leaf hops absorb in quarts per ounce. but it must be a fixed ratio, given a fixed moisture content for the dried hops. I usually start with 6.5 gallons plus, assume 1 gallon boil off and end up with a full fermenter (5 gallons) plus some wet hops. That approximately works out to 1 gallon evap., 1/2 gallon absorption for 3 ounces leaf hops, for 60 min boil. This is all a guess. Play around with your quantities and you'll figure it out.

 

[cactusgarrett]

The value i use for whole hop absorption is around 0.1gal/oz (that's 0.4qts/oz). That has gotten me into the right ballpark for predicting loss with large amounts of whole hops.

 

[jmancuso]

I didn't top off with water. I figured at 1.072 I'll take 8 gallons of iipa.

 

[jmancuso]

Can wort shrinkage happen twice? I ran out of propane with 15 min left in the boil and it cooled a little bit for a half hour. I brought it back up to a boil and let it boil for 5 minutes before doing my 15 min hop additions.

 

[kanzimonson]

Here's the way I look at it: gravity is much more important than volume. Yes, I realize they work hand in hand. And yes, you're going to have some problem with liquid displacement and absorption when you add any hops. I suspect leaf hops are worse than pellets. I don't know what to think about affecting the evaporation rate, but my gut says it's a minimal effect.

Here's what I do: runoff until I hit my preboil volume and take a gravity reading. If I have 7gal at X gravity, then I can figure out what I want my postboil gravity to be. Then, I boil until I hit this. So even if my hops displace the wort so that the actual liquid level is above my 6gal target, if the gravity is correct then I have boiled enough. Unfortunately, with big hop bills the liquid level is going to trick you into thinking you haven't boiled enough. I hope I'm making sense here.

 

[jerryalan]

Here's what I do: runoff until I hit my preboil volume and take a gravity reading. If I have 7gal at X gravity, then I can figure out what I want my postboil gravity to be. Then, I boil until I hit this. So even if my hops displace the wort so that the actual liquid level is above my 6gal target, if the gravity is correct then I have boiled enough. Unfortunately, with big hop bills the liquid level is going to trick you into thinking you haven't boiled enough. I hope I'm making sense here.

How do you time your hop additions? If you have a 60, 30, and 15 minute hop schedule and you hit your target gravity after 45 minutes wouldn't that affect how your hops were utilized? 60 minute hops become 45, 30 become 15, and 15 become flame-out. That would affect your bitterness level and flavor?

 

[kanzimonson]

Everything I said is on top of the fact that I have a pretty good idea how vigorously I need to boil to hit my target gravity/volume in 60 minutes.

Boil strength and evaporation rate are just one of those things you have to experiment with to figure out your system. A refractometer helps a lot, but if you don't have one you can use a ruler to help you see what's going on. Yeah, the ruler won't help you adjust for hop/liquid displacement, but it's good enough for most beers. I did some measurements and found out that each inch of depth in my boil kettle amounts to .7gal... I just dunk it in, do some multiplication, and I know exactly how much I have. None of this notching a stick nonsense.

 

[Rundownhouse]

None of this notching a stick nonsense.

...except for the stick you bought pre-notched at 1in intervals. Some people choose to use a stick that measures in gallons, some prefer to use a stick that measures inches and then convert that figure into gallons, I guess.

 

[ajf]

The value i use for whole hop absorption is around 0.1gal/oz (that's 0.4qts/oz). That has gotten me into the right ballpark for predicting loss with large amounts of whole hops.

See https://www.homebrewtalk.com/f13/whole-hop-absorption-28263/

That's very close to what I get.

-a.

 

[kanzimonson]

...except for the stick you bought pre-notched at 1in intervals. Some people choose to use a stick that measures in gallons, some prefer to use a stick that measures inches and then convert that figure into gallons, I guess.

the reason I do it with a yard stick is because it's only one measurement: you measure the pot, do the calcs, and you've got the gallons per inch number. Compare this to taking a one gallon jug/pitcher and measuring 5, 6, 7, 8 or more gallons, notching a stick each time. That's a lot more room for error.

 

[calpyro]

nice

 

[kanzimonson]

I'm not sure I believe you that they absorb less wort. Definitely on the imparting flavor and even bittering, but why would the same amount of mass absorb less wort if it were chopped finer? The finer we grind grain, the more wort it absorbs, right?

 

[calpyro]

I'm not sure I believe you that they absorb less wort. Definitely on the imparting flavor and even bittering, but why would the same amount of mass absorb less wort if it were chopped finer? The finer we grind grain, the more wort it absorbs, right?

My best reply is to give a try for yourself. I have found that the more compact the layer of trub and hop matter in the bottom of the kettle, the less wort that is absorbed. By chopping the whole hops into a finer consistency, they will settle into a smaller area similar to pelletized hops thus absorbing less. I even bought a food processor just for hops.

 

[kanzimonson]

Again, that's not really an indicator that they're absorbing less - just settling better. Still a great idea though.

 

[jerryalan]

Again, that's not really an indicator that they're absorbing less - just settling better. Still a great idea though.

He might be on to something here. The wort could be absorbed between the cone bracts filling in the porous spaces. Similar to capillary action.

 

[kanzimonson]

Good point.

 

[calpyro]

great

 

[ajf]

You are mistaken. Whole hops absorb more wort than pelletized hops, or in my case whole hops that I chop in a food processor. If you need further information see Page 45 in John Palmer’s book “How To Brew”, Table 6 Hop Forms and Merits disadvantages or whole hops: “They soak up wort resulting in some wort loss after the boil”

I really doubt that this is true. I think they both absorb the same amount of water, but the difference is that whole hops are so much easier to filter out on the way to the fermenter, so the hop material and wort absorbed by that material is more likely to stay in the boil kettle. With pellet hops, or pulverized whole hops, you would need a much finer filter to keep the hops out of the fermenter, so you transfer a substantial amount of the hops (and the wort absorbed by them) into the fermenter.
If you read Palmer more carefully, he mentions that the pellet hops produce a lot of sludge in the kettle. This sludge is simply very small pieces of hop combined with the absorbed wort.

-a.

 

[calpyro]

sounds good

 

[samc]

Next time you brew, squeeze the hops if in a bag or use a potato masher to push down on them to extract all that extra wort. It can be a large amount but no way is it three gallons in a 5 or 10 gallon batch unless you have pounds of hops in the wort.

Also watch how vigorous the boil is compared to when you used pellets and see if that is part of the problem.

 

[cactusgarrett]

One disadvantage I see to processing your whole hops would potentially be the loss of lupulin due to the excessive handling & transferring of the hop material during the fine "chopping" process. Pros and cons either way, i suppose.

 

[kanzimonson]

Calypro, when you chop them do you consider them to have the same utilization as pellet hops? Or somewhere in between whole and pellets?

 

[jmancuso]

I don't think the utilization is a big deal. Even with my 17.9aa columbus bittering hops it calculated to 22 ibus vs 25 ibus for pellets, and the difference was smaller with the flavoring hops.

I'm not looking for a way around the absorption from the leaf hops, I'm just looking for a way to factor it in. I don't care if they absorb gallons of wort I would just like to know how much larger to make my starting volume. That .4 qts/oz sounds like a start for experimenting, however according to that i would have lost 1.4 gallons which doesn't account for the other 1.6 gallons I was short.

 

[AiredAle]

I think we have a semantic problem here. I would define absorption as the act of a liquid being taken into a solid material, like rice absorbing water as it is boiled. The hops will absorb the same amount of wort regardless of their shape or size. Whole, chopped or pelletized, they will all absorb the same amount of wort.

An ounce of whole hops take up more volume than an ounce of pelletized hops, and that extra volume is the space between leaves or petals, what ever you want to call them. This space will fill with wort and capillary action will keep the wort in these spaces when the kettle is drained. Pelletized hops don’t have this extra space, since they pack well together when the kettle is drained.

Bottom line is more wort is retained in the kettle with whole hops than with pelletized hops, but the absorbed volume is the same. By chopping whole hops up in a food processor before use, the volume between the pieces of hop cone is reduced from that of the whole hops so less wort is retained between pieces when the kettle is drained, even though the same amount of wort is absorbed by the chopped hops.

 

[Dog House Brew]

My whole hop absorption multiplier is .12 on my new system and was .16 on my old system. It will only take a batch or 2 and you will get the number for your system.

 

[jmancuso]

My whole hop absorption multiplier is .12 on my new system and was .16 on my old system. It will only take a batch or 2 and you will get the number for your system.

.12 gallons per oz?

 

[calpyro]

wow

 

[calpyro]

yep

 

[calpyro]

good

 

[Espi]

I will chime in late and on the in-experienced side of things. I did one batch with whole fresh hops that a friend had on hand.

I had always used pellets in the past hand never had any issue with hitting my volumes. (well before I go my new kettle so I am now figuring out boil off rates again)

This batch with out knowing left almost a gallon low in the carboy. It was 4 oz of fresh Cascade.

 

[calpyro]

nice

 

[Dog House Brew]

.12 gallons per oz?

yes