Dextrins, Dry Hopping & Recipe Design

Homebrew Dry Hopping

This is a subject I’ve been mulling over and researching on and off since I brewed Lumford and Raven at Thornbridge, the Key questions for me were:

  1. Why can dry hopping with T90 dry the beer out?
  2. How do I brew beer that is as good as US and NZ beer?
  3. How do I avoid brewing beer with vegetal/grassy characteristics?

I did a lot of research into recipe formulation, dry hopping techniques and literature reviews and learnt;

  1. British brewers are obsessed with a low terminal gravity
  2. The more body (up to a point) in a beer the better able it is to express hop character

With these conclusions in mind I determined that to brew a good dry hopped beer I need body to support those hops, I didn’t know why at the time but I couldn’t brew a beer that would hold the hops the way I wanted without the beer turning out astringent and vegetal.

Initially my thoughts were that it was the alcohol sweetness in bigger beers that does the job that I wanted so decided that 1.050 would be my cut off. No dry hopping below 1.050 worked well although it did have some strange variables that I wasn’t pleased with.

I also endeavoured in trials to raise the F.G.

After a long process of dry hopping trials I determined that timing also has a part to play. So I designed Imperial Black and Axe Edge to alleviate my problems. Imperial black worked well, exactly the kind of body I wanted, Axe edge was rather more variable, I still had no real understanding of how the mechanism worked and I was still confused with recipes from top US brewers that I had seen. My understanding at that time was:

  • Dry hopping in FV warm at the end of fermentation (1.020 or below) worked well both with maximum aroma appropriation and decrease of astringency in finished beer. This was confirmed with some correspondence with US breweries.
  • Higher mash temp seems to help the relative lack of astringency but not always
  • Maximum two to three days on dry hopping seems to give the best results.

At that point kegging became a requirement but my concerns were that if I could barely control the outcome in the finished beer at relatively high temperatures and low carbonation in bottle and cask, intuitively the finished beer in keg would need work? With this in mind I determined that keg product would need a tweaked recipe or tweaked process.

But How? I don’t understand why the beer is not the way I want it to be so how can I adjust it in any way, traditional methods of increasing mash temp don’t seem to work, water ion adjustment doesn’t work…?

At that point I came across an article in the 1941 Institute of brewing research scheme entitled ‘The Diastatic activity of hops, together with a note on maltase in hops’ That coupled with my knowledge on US maltbill recipe design enabled me to have an ‘Ahhhhh’ moment.

To cut a long story short, the paper showed that in their trials:

  • Diastatic enzymes are being denatured during the mash/lauter/boil process
  • Dry hopping reintroduces diastatic enzymes, specifically Maltase back to the beer that are able to continue conversion and breaking down of any remaining long chains making a more fermentable beer

These two factors create a dryer beer. But this didn’t really answer my question, why can’t I control this using mash temp and how do the Americans and the New Zealanders do it?

A little bit of research answered these questions for me

  1. If I was to truly add body via dextrins to a beer with mash temp the mash temp would need to be upwards of 72-75°C, hard to do, energy requirements are high, temp losses are great and dextrin amount is undetermined and probably able to be converted by introduced enzymes.
  2. The US and NZ brewers I like, use fairly liberal amounts of caramalt and carapils in their beers, between 5-8% even in beers I would think need less body, IPA’s Imperial IPA’s and US Barley wines. In some cases they use sugar and caramalt and carapils and mash at 68°C. This always seemed counter intuitive to me but now I understand it.
Pliny the elder homebrew recipe

Note the levels of dextrinous malt used in this US recipe

3. Crystal/cara malts are created by stewing green malt at conversion temperatures (66-71C) to convert starches into fermentable and unfermentable sugars, they’re then dried and roasted to the appropriate colour. Some of these unfermentable sugars can be converted to fermentable sugars in the mash but carbohydrates that participate in the Maillard reaction yield compounds that are unable to be converted to fermentable sugars.

4. US brewers are brewing for kegging and dry hopping, a dextrinous body from specialist malts counteracts the diastatic nature of dry hops and the body stripping nature of increased carbonation and decreased temperature.

5. It seems to me that a lot of knowledge and trial and error has gone in to the design of these big US IPA’s. The use of dextrinous malts, mash temp and sugar additions create that perfect balance required for these beers

So looking back, Imperial black worked well because I liberally used crystal malt in it, my goal was to top up the colour so I wouldn’t have to use as much Carafa special III. It did this but had other benefits to the finished beer.

Axe Edge had a fair amount of caramalt in it but not as much as US beers do so was rather more variable. Carapils would have fixed this problem.

Going forward my recipe design has focused a little more on caramalt and carapils amounts in my IPA’s under a certain gravity to test this theory. This has given me excellent results, hop character has been enhanced where a more tailored malt bill approach has been implemented in beers that previously struggled.

A great example of this is the recent collaboration with Marble brewery ‘Howgate and Kemp’ a NZIPA. We utilized caramalt and carapils in the mash and it really created a malt character that gave us exactly what we wanted from the hops, a really juice hop character not at all astringent even though it was heavily dryhopped.

Formerly of Fullers, Thornbridge and Buxton. Now a freelance Black IPA advocate, homebrew geezer and creator of Baby Back Bacon Black IPA™

3 Comments

  • Reply December 28, 2014

    Dan

    Great article James. Coincidentally I tried one of my hoppy pale ales tonight only to find the aroma hops had faded considerably and the bittering hops had become quite astringent. The brew and subsequent ferment when well and a decent amount of whirlpool and dry hops went in. I think the problem lies mostly in the grain bill – fairly simple with only around 3% Crystal 60. In addition the FG was very low (~1.008) with an abv of around 3.9%. After reading the above article I think the addition of some caramalt and carapils would have helped preserve the hop character.

    Thanks for the info and keep it up.

  • Reply March 1, 2015

    pdtnc

    just doing a bit of Port66 catch up, not much time for reading stuff that isn’t directly to do with the graft of preparing premises to be a brewery.

    You mention above a certain gravity, 1060-1070 I’d need to cut the cara or drop the mash temp from 69c to 67-68c otherwise its harder to get the attenuation to chosen abv.

  • […] crystal or caramalts in US style IPA’s that would make them far to drinkable and stop them being fizzy hop water …WE NEED TO USE BASE MALT […]

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