The Malts in Porter and Stout



[Originally, the content below was the first section of yesterday’s post on historical brown malt. I decided to separate them to reduce the length. Also, this posting will appeal to a more general audience].

The Keynotes of Porter and Stout

The keynotes of porter and stout are, i) their dark brown-to-black colour, and ii) a taste variously described as roasted, toasted, burned, smoky. Today and since the early 1800s, porter and stout are made from a base of pale malt. A small amount of black or other roasted malt, or sometimes roasted barley or wheat (raw), is added for desired colour and flavour.

Blonde lagers, pale ales, and IPAs are made from (broadly) a similar base malt, but generally do not use the roasted malts. Where they do, it’s a very small amount for colour or minor flavour contribution.

Thus, for most beer today, a pale base malt is used. But darkish malts can also form the base, e.g., for Munich dark lager. Still, Munich malt, and the lighter, amber Vienna malt, are different from the roasted malts used for porter. They are more “luscious”, less harsh, and don’t have a bitter, roasty edge. Porters and stouts tend to have a burnt, expresso or other coffee-like signature. Munich dark lagers, as well as many brown ales, can have sweet, caramel, or drier biscuit notes. (For now I’ll leave out the special class of malts known as caramel and crystal malts although these are not unconnected I believe to the earliest brown malt).

What Kilning Does for Porter Malt

Kilning malt at high temperature (over 212 F) tends to lessen or impair enzymes resident in the barleycorn, which are needed to degrade its starch into fermentable sugar. Modern black and brown malts have no enzyme due to their high roasting temperatures – 400 F +. For modern porter, this is of no moment as the pale base malt contains enzyme in abundance. For German dark lager, the dark malt is processed and dried in a way to retain sufficient enzyme to convert itself in the mash to simple sugars and dextrin. Such malt notably can be finished off in the kiln at about 212 F, well under the range today for black malt, say.

In brewers’ parlance, any malt that is about 50 degrees Lintner (50dL) – one source goes as low as 30dL – can self-convert. Some German dunkel malt, albeit dark brown, meets that threshold. But for modern black and brown malts, the temperature of the roasting impairs the diastatic potential. Modern dark brown and black malts contribute, by contrast, their colour and flavour to porter and stout. Any starch which survived the roasting process will be converted by the ample enzyme in the pale malt.

What Mashing Does 

Mashing is the steeping of these malts, after grinding, with hot water. The drained mash is then boiled with hops to form wort, which is fermented into alcohol and CO2 gas with yeast. Mashing is necessary to convert the malt starches into shorter polymers, or simple sugars, which are susceptible of fermentation. With grape juice, you have the sugar straightaway. Same thing with apple juice, for cider. With beer, you must change a starchy mass into sugar before you can make alcohol. Mashing results in other compounds too, notably dextrin which adds body to beer but isn’t fermentable by normal beer yeast.

Malting and Mashing Permit Vital Enzymatic Action

Malting and then mashing thus activate the barley’s resident enzymes, and also contribute positive flavour effects. In malting, the grains are moistened so they partially germinate. Generally today, this takes place in open box-like structures or huge cylinders. Originally, all malt was spread and turned “on the floor”. Some still is and is considered a choice form of barley malt.

Germination starts the rootlet growing much as would occur when grains come alive in the spring in warming, damp soils.  What nature provides as nutrient for a growing plant, the brewer emulates for his own, quite different purpose. After soaking and germination, the grains are dried in a kiln – both to preserve the malt and for positive flavour effects – and can then be used in mashing and brewing.

When the dried malt is hydrated in mashing, the starches are released into solution. The activated enzymes complete the conversion of the starches to cereal sugars. If raw grains are added to the mash such as raw barley (unmalted), corn, or rice, the enzyme power of the barley malt is strong enough that it converts those grains to fermentable sugar too. Brewers use raw grains for various reasons, mainly IMO because of cost factors. There is no preliminary malting, for example, which saves on the cost. And generally, corn is cheaper than barley. Whether the taste results are equal to 100% malt beer is up to the consumer. I think all-malt beer is superior, generally.

Porter and Stout Originally Used 100% Brown Malt

Porter developed in England in the early 1700s. Until late in the 1700s, it used all-brown malt, no pale. This is attested by many sources. Brown malt was cheaper than paler malt because after higher-temperature drying to get the dark and toasted effect, some of the starch was used up, leaving less to turn into fermentable sugar and alcohol. Still, you could make a beer at an acceptable strength and affordable price. In time, people got used to the roasty, burned taste of the brown beers that came finally to be called porter and stout.

After about 1800 when all malt had gone up in price due to increased taxation, and better science gave a good handle on alcohol yields, brewers started to mix brown malt with pale malt. This permitted an overall better return than using brown malt alone. But the beer became paler, a problem ultimately solved by development in 1817 of a super-roasted form of malt, black malt.

The ability of 1700s brewers to mash all-brown malt and brew an acceptable beer was due to two things: those malts were kilned at much lower temperatures than modern roasted malts, and mashing times were very long by modern standards. Any mash, even a raw grain mash, will convert given enough time. It is not economic to do so, however, due to the extra needs for manpower and energy.

I believe the flavour of both 1700s and 1800s brown malt was more or less similar, with the blown malt subset possibly having its own signature. One must allow too that many maltsters had their own proprietary methods or made a bespoke product. In general, these malts had a hint of wood smoke flavour. It was probably stronger in the 1700s porters since the malt was unmixed with pale malt which generally was cured with some form of coal, or straw in some cases.

Beers Made With Today’s Brown Malt

Recently I discussed Black Creek Porter made in Ontario, which I understand uses a measure of brown malt. Indeed the beer tastes different than your typical pale malt + black malt/roasted barley porter. Did the brown malt taste come close to that of 1700s or 1800s brown malt? It’s impossible to say, but I believe the flavour did resemble some of those malts. The taste is woody and arbour-like, not smoky/combusted since no wood is used in the kilning, but it is still different from the expresso edge of black patent malt. Certainly the beer tasted very good and would have been enjoyed I believe by our fellow Georgian beer fanciers.

Here is a listing for a brown malt made today, by Crisp Maltings in England.

Note re image: The image above was sourced from Cork City And County, Ireland, archives, here, and is believed available for educational and historical purposes. All feedback welcomed.