Decoction - The Toast Test

Brewing Processes
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Decoction - Defined

Decoction literally means ‘to extract by boiling.’

Decoction mashing is a method of extracting starches from malted grain by boiling the thickest portion of the mash.

This raises the malted grains above the starch gelatinization temperature, breaking the cell walls of the kernel, allowing the starch to diffuse into solution.

An Analogy - The Toast Test

A fresh piece of bread when toasted will evaporate the moisture content during the heating cycle causing chemical reactions known as maillard reactions and browning known as melanoidin formation.

Take a dry, already toasted piece of bread and toast it again. It will char and burn due to pyrolosis.  The absence of moisture (evaporation) causes rapid decomposition of the material.

Placing a saturated piece of bread in the toaster and it will not start to develop flavor (i.e. toast) until it has evaporated a certain amount of its moisture content > 80%+ percent.  In fact it may not toast at all.  It will probably become a hot mushy mess at the bottom of your toaster (depending on the design of your toaster oven).

Malt - Kilning

After steeping and germination, malt is kilned.  Heat is applied in a controlled fashion starting at various moisture content levels and following a specific temperature profile.

Much like toast, key to development of flavor in malt is the moisture content of the malt at the start of kilning.

  • A pilsner/pale malt may start kilning at 8-10% moisture.
  • A vienna malt may start kilning at 15% moisture.
  • A munich malt may start kilning at 20-25% moisture.

Vienna and Munich malts may also be “stewed” or mashed at the start of kilning to develop more flavor.  Crystal and Caramel malts are “stewed” or mashed with up to 50%+ moisture content.

Toasting (slight moisture content) and Roasting (no moisture content) begins when the moisture content of the malt drops to near 0%.  Light heat for short time yields a toast, high heat for a longer time yields a roast.

Moisture Content

The fact is both toast (Bread) and malt flavors hinge on their moisture content and temperature profile at the time of toasting/kilning.  (Of course your toaster oven probably doesn’t have profiles as much as set temperatures.)

The Great Debate

Does decoction mashing develop malt flavors?  To answer that we need to ask a few questions:

1.) Does the malt contain moisture?

Provided that a reasonable crush was given for the malt it should contain moisture from the initial acid or protein rest.

2.) Is the temperature high enough to develop flavors (Maillard Reactions)?

Depending on the thickness of the decoction the temperature should be at least 212F (at sea level) and could be higher for the grains and liquid touching the bottom of the pot.

3.) Is even air/evaporation available to the malt?

Even readily exchanged moisture (i.e. evaporation) is not present unless perhaps the decoction is very thick and constantly stirred (isn’t that how it’s supposed to be done?) at which point it’s easily burned/scorched/seared.  As with the saturated bread you may just have a hot, mushy mess at the bottom of your boil kettle.

The Conclusion

Since there is no active, even, evaporation (air/moisture exchange) occurring at optimal temperatures, the best one can hope for is very slight caramelization and perhaps some color change due to the caramelization.

It’s best to get malty flavors and aroma from properly made malts instead of relying on decoction mashing.  If you do attempt a decoction make sure it’s very thick and constantly stirred.

The common test for this is to decoct one batch and infusion mash another doing a double blind triangle test at the end.  May I suggest the toast test instead.

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Can I just throw some wet lucky charms in the microwave?

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Wow, I love the analogy with toasting bread. Thanks for the insight. And about those lucky charms :stuck_out_tongue:

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Cool info. Sounds right. Reads like a cut n paste. Good work for first post. Now we’re dying to know who you are and some background on the info.

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good stuff.

…my suggestion as always is that if something works for you over other options, keep doing it.  You’ll never ever hear me say that you have to do a decoction to create a certain style.

cheers–
–Michael

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The gelatinization temperature of malted barley is in the 65F range, which is why we can single infusion mash. Decoction heat explodes the smallest starch granules, which makes that starch available for conversion.

Caramelization requires high heat and low moisture. Fructose caramalizes at 230, other sugars above 320F.

Maillard reactions proceed at high pH, more above 7, and at low moisture. There are exceptions, long boils of wort produce Maillard reactions, and that case is mentioned as an example in “On Food and Cooking” by Harold Magee.

The toast analogy is one I use to describe various grains and their color and taste, as everyone knows toast.

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It’s original.  Just something I had to get off my chest in hopes that it would either get shot down or prove of some worth.

I’d recommend the 1985 Special Edition Issue of Zymurgy which contains an article by Greg Noonan on Decoction.  Also Malts and Malting by Dennis Briggs.  Plus many more…

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The proteins and amino acids necessary for the maillard reactions are definitely present in the decoction.  Thickness of the decoction and length of boil are most certainly factors in the caramelization argument.  A very thick decoction with a very small amount of liquid or even liquid mostly trapped in grains may be similar to boiling down a volume of wort.

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Some people swear by decoction while others swear against it, the debate goes on. The last year or so I’ve almost exclusively brewed lagers. I started out with a single infusion rest then tried step hochkurtz type mashing and now I do a single decoction. I have to say the later has been my best lagers to date but I’ve also made other improvements to my brewing so I think its time to go back and try the same recipes with other mash techniques to see if things have changed.

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Another purpose of the decoction mash is to attempt to extract more starches (and proteins!) than can be had by simple infusion.  That point seems to be left by the wayside and is perhaps not as well tested.

Running a decoction mash using a strainer to pull the decoctions would be an interesting take.  In doing so, a good thick mash should be had, combined with constant stirring - a very malty flavor would be developed ::Shocked:: along with a mass of caramel :wink:

I’m neither for or against a decoction, just attempting to look at it through the critical eyes of a scientific point of view - What really happens during a mash boil?

As an aside, I’d like to know how the whole ‘decoctions make for a maltier beer’ thing got started.

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Someone should take an old dough mixer and add an induction heater to it, then you could have an automated boil while continuously stiring decoction machine.

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If water is present you are not getting caramelization, as was pointed out the temps for that to occur are much higher than boiling.

As far as what a decoction provides to a beer. IME a decoction provides an intangible complexity worth at best a point or two on a score sheet. I never found my decocted beers to be more malty, simply a slight bit more complex in the malt profile. YMMV.

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Debatable.  Depends on the thickness of the mash, the volume of liquid, the temperature of the surface of the boil kettle and the dryness of the mash.

The temp of the boil kettle surface could be high enough to cause caramelization on small droplets or volumes of liquid especially in a “dry” mash boiled for long enough to cause the grain to absorb more of the water.

Granted, I’ve only seen a few people do really dry decoctions.

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Wort is at best 2% fructose (Palmer) and that caramelizes at 230F. Sucrose and Glucose are 320F and Maltose 356F. So unless the temp is above 230F you are not getting any caramelization and for sure you are not getting any significant caramelization until you are above 320F. Again, if water is present, caramelization is not occurring, simply maillard reactions.

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Sure, if water is present, however in a very dry decoction with a very low to no volume of wort on the bottom of the kettle, it is conceivable that caramelization does in fact occur.

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I personally have never seen anyone decoct to that level. When you do, snap some photos or take a video. :wink:

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I’ve seen people come close.  When there’s not much liquid in the boil kettle the mash really has to be stirred as it is in effect being boiled down.  That’s where the strainer experiment would come in to play.

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What do you mean by strainer experiment?

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On the strainer thing - that is how we do it. You do need to get some liquid in there too.

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Can you give references to back that up?

Even in vigorous boils, you have about +10C on the kettle surface, so about 230F at best. We are in the nucleate boiling regime. If you get hotter, well that takes alot of heat flux, and you get into the Leidenfrost boiling and film boiling ranges - not good.

German brewers that decoct mash thin and pump a slurry over - grain and liquid.