Hop Backs

[Liam Callaghan]

I've been doing a little bit of reseach on hop backs recently and their historical use.  Not that I need anything more on my plate but it's nice to have a private project to work on as well.  Between myself and a few mates we have pulled up a few good examples (Blichman hop rocket to name one) and I'm pretty sure I have the design right in my head but just had a few questions and wanted to know what others thought.

I quite enjoyed reading my first article on them being used as a filter for the hot wort to remove trub prior to cooling.  This got me quite intrigued and I am itching to make one and try it out.

A few questions have been answered from our research, they need to be sealed, low flows so as not to compact the hops and stop the flow of wort (1.3 litres/m from Blichman).  Volume of hop flowers 2oz/5gal of wort.  Filters need to be added to help contain the trub. 

The volume of the hop back for an average 25 litre brew if I want to filter the whole wort rather than just add the hop flavour (Blichman Rocket is more of a flavour addition than a filter) but I think a dual screen and the same volume of hops should suffice for this.  So no more than 5-10 litres volume in a cylinder.  Filters sealed to the edge to reduce river affect.  They can be heaps smaller if you just want to add flavour of course.

Still undecided was the introduction of air into the hot wort and how this hot addition oxygen affects the beer - if at all.  My understanding was it did have an adverse effect on the beer but I don't know where I know that from or what it does to the beer :(

Others say no, oxygen is good at any time post boil just get it in there!  Yet more say it is recommended not to add oxygen to hot wort but there is no research to say what it does if you do.  So still a mystery but if anyone can shed some light on this it would be appreciated.

Also if they know what the risks are of adding oxygen via a hop back to filter the hot wort. 

I'm almost hoping Richard has already built one!

So who has used one?!  Whats the guts of 'em?

L.

 

[Crusader-Rob]

Interesting Discussion, I've read about people making these out of pressure cookers? hbt.com has information.

[Liam Callaghan]

If I get a chance tomorrow I'll link up the ones we found, just kep getting interupted at work with work...

Unless Tom reads this and can add them?

Pressure cooker would be a nice cheap option. 

Time to raid the mother inlaws kitchen cupboard!

[Hillman]

I have a hop rocket and it seems to do a good job filtering. At least the beers I've been left with a lot less crap in the fermenter afterward. The drawback with having one of these in NZ though is that it requires hop cones, not pellets, which are pretty hard to get hold of and can only be gotten in NZ produced strains.

[Hillman]

*at least the beers I've run through it

Shouldn't try to post and cook nachos at the same time.

Also the hop rocket can be used as a randalizer by changing the fittings. Whatever you come up with you might want to consider doing that because it really does give a hoppy blast to the beer.

[Liam Callaghan]

Here are some of the links we found

http://discussions.probrewer.com/showthread.php?18037-Hop-Back-Design

http://www.blichmannengineering.com/HopRocket/HopRocket.html

http://www.pjmuth.org/beerstuff/hop_back.htm

 

The last one Pauls Gadjets is pretty good, could make it in a an hour or so.

 

Even with limited hop varieties it would be good to try it out.  Especially for people growing their own hops at home.  I will speak to NZ Hops about flowers see what they can provide.

 

Having never used it I'm not sure what hops to enquire about for flowers.  Anyone have any suggestions?

Not sure if we can get away with some of the high alpha (same as simcoe)

[Matt Smith]

Charles Bamforth talks about the hot side aeration thing a lot, and basically says that while it may contribute the smallest amount to flavour instability and staling over time, the difference is negligible compared to the negative flavour impact that poor storage has on beer. Eg if you store your beer at 20 degrees for a couple weeks, you have already done worse for your beer than would have been avoided by going to all the lengths people go to to avoid oxygen pickup on the hot side. So for commercial beer atleast, all that effort is essentially wasted as soon as the beer enters the distribution chain (unless they have refrigerated distribution)

So basically, avoid oxygen pickup on the hotside where you can, but don't be too concerned about it. I haven't read any of the articles you posted yet, but from what I understand wort fills the hopback from a bottom inlet first, and is drawn from top, if this is the case then oxygen pickup will be pretty minimal anyhow.

[Liam Callaghan]

Great clarification Matt, thanks man!

Hop Backs ftw!

Now to make one...

[Adam Sparks]

Hey Liam Even that last link you posted is more complicated than it needs to be.... I use an old coffee can and some hose barb connecters that I got from enco.co.nz

I just pop a piece of swiss voil in the hop back and jam that sucker full! I also dont fill from the bottom (although you could) as I dont want to waste 2 liters of wort. If you regulate the output before hitting your chiller then the can fills up and you have quite a lot of wort in contact with the hops before cooling.

simple but effective

[Druid]

It was George Fix who focused on hot side aeration - he basically identified that you should only aerate below 27-28 deg C.

I've got his hardcopy book at home but heres a link that talks about it.

http://beersmith.com/blog/2010/01/19/aeration-for-home-brewing-beer/

[Matt Smith]

Cheers,

Yeh its an interesting topic and there seems to be firm opinions on either side. There is a study somewhere by Bamforth (I think) where the flavour stability of beers with aeration on the hot side were compared with beer without, i'll see if I can track it down.

Many commercial brewers use an internal collandria in their boil kettle, it's basically an open cylinder in the centre of the kettle, whereby convection sends boiling wort shooting up the tube and out the top where it hits a concave dome mounted above the cylinder and splashes back down on top of the boiling wort. Basically its used to achieve high utilization and an efficient boil. The way I see it, this is essentially aerating the boiling wort constantly for 60-90 minutes. If this is acceptable to large commercial breweries who spend millions on flavour stability, then surely the staling effect must be incredibly small. Perhaps there is more to it than that