Robust Porter

Overview

Robust porter is a rich tasting dark ale. It is characterized by complex toasted and burnt/roast flavors with a healthy dose of crystal malt sweetness. The flavor of robust porter is often likened to dark chocolate and coffee. These foods also get many flavors from high temperature roasting. The beer style robust porter has a notably wide range for interpretation as the brewer chooses. Examples may vary substantially in terms of alcoholic strength, sweetness versus dryness, hop-bitterness, use of late hop additions, and other properties. Consequently porter is particularly well suited to experimentation and exploration of new flavors.

Vital Statistics

O.G.	1.048 – 1.065
F.G.	1.012 – 1.016
ABV	4.8 – 6.5 %
IBU	25 – 50
SRM	22 – 35
Volumes CO2	1.7 – 2.3

Statistics from [1] and [5]

Related Styles

As the name implies robust porter is a more robust version of the related brown porter. It is more robust by nearly any measure: gravity, hop-bitterness, and roast character. Brown porter is thought to resemble the earliest porters made using primarily brown malt, while robust porter reflects later versions with slightly higher gravity made using a mix of very pale malt and very dark malt. The exact distinction between robust porter and some examples of stout is minimal. Often prominent roasted barley character is considered to be the mark of a stout. Baltic porter is a generally higher gravity version of porter that can be lighter in color and is sometimes made using lager yeast.

History

During the Industrial Revolution, porters were hardworking laborers who made their livelihood hauling stuff around large cities. Unsurprisingly, porters enjoyed drinking some ale from time to time. Porter the beer style became known as their preferred beverage and is named for them. The history of porter is intertwined with industrialization. Porter was one of the first mass-produced beers. Its popularity coincided with breweries learning to take advantage of economies-of-scale. At the same time brewing was becoming more empirical and brewers were becoming more cost conscious. In response beer recipes were refined for improved efficiency and made use of new malts made possible by industrialization of the malting process.

Just prior to the development of porter, it was popular in London to drink blends of several different ales mixed just before consuming. There are records of pubs serving a beer cocktail known as “three threads” poured from three separate casks. There is also at least one mention of something called “five threads.” It is unknown exactly what the constituent ales in these blends might have been like. It is thought that the three threads were: aged brown ale, fresh brown ale, and pale ale. Mixing must have conferred some benefit to justify the extra effort (i.e. brewers producing more types of beer, publicans managing a stock of several distinct beers, and drinkers waiting for a complicated pour). Likely the mixing rounded out some flaw or made up for some shortcoming in each “thread”.

In 1722 Ralph Harwood, a London brewer and pub owner, started selling a pre-blended and pre-aged version of three threads called “entire” or “entire butt”. Records show many other brewers following suit almost immediately producing their own versions. [4] Entire soon became known as porter. These early versions of porter probably resembled what we now call brown porter more so than robust porter. It is known that they made extensive use of something called brown malt. Aside from probably being brown, we can only speculate about the exact properties of this malt. Since it was used in such high proportions it must have had some mash enzymes, but it is unclear exactly what shade of brown it was and what flavors it may have had.

The aged quality of early porters was an extremely important feature for consumers. To take advantage of economies-of-scale, porter was aged in huge aging vessels. As porter grew in popularity breweries began to compete by building larger and larger vessels. Sometimes breweries would celebrate newly constructed vessels by hosting dances inside of them. In 1814 one such large vessel ruptured and flooded the surrounding neighborhood with thousands of gallons of beer, destroying homes and killing dozens of people. [3]

In the early 1800’s trends moved towards slightly higher original gravities and a more robust formulation. It was around this time that malting techniques started to change. Traditional floor malting began to give way to new indirect-heat methods. In floor malting, the malt is kilned by spreading it across the floor in a heated room. The drying malt is periodically raked by hand. In the indirect-heat method, the malt is dried in a heated rotating drum. Floor malting results in a less uniform degree of kilning caused by differing amounts of heat exposure. Due to only periodic mixing, some grains spend more time near the hot floor and get darker. In contrast a rotating drum keeps the grains constantly mixed allowing for a basically uniform product.

The indirect-heat style of kilning made it possible to produce both very pale and very dark malts. The process for making black patent malt was one of the first patents ever granted in 1817 and depends on a drum-style kiln. Brewers were able to use the recently popularized hydrometer to learn that pale malt has a better yield of fermentable sugars. Porter recipes were reformulated to achieve dark colors using primarily pale malt with small amounts of very dark malt, and this is the beginning of what we now call robust porter. Interestingly, many brewers continued to use small amounts of intermediate colored malt.

During the Colonial Era in the future United States porter was a popular beer style. English colonists came to the Americas with their taste for porter. Colonial brewers often made use of adjuncts such as corn, molasses, squash, and even peas to make up for shortages of suitable malt. [6] Porter in various renditions remained a popular style in the United States until Prohibition. In the United Kingdom, porter eventually fell into obscurity, and by 1953 it was more or less extinct as a commercial style. Fortunately, the style was eventually revived as a favorite of craft-breweries.

Brewing Robust Porter

Grains – Pale base-malt along with generous use of various specialty grains. Features intense roast grain character from dark grains such as chocolate malt, black patent malt, and less commonly roasted barley. Generally some crystal malt sweetness is used to reduce the acrid edge from the dark grains.

Hops – Typically Typically American or English hop varieties may be used at all stages of the boil or just for bittering.

Yeast – British or American ale strains that ferment clean or produce a light ester profile.

Water – Moderate to high carbonate levels (hard water).

A good robust porter is a complex beer with many flavors intermingling and vying for attention. All porters have some roast flavors, dark chocolate, and possibly edging into burnt-acrid territory. The sweet flavors can run from caramel to toffee to malt to vinous. The hops can be just a simple bittering addition or a more complex affair. In some ways it is a style well suited to overdoing it: overdoing the roast flavors, overdoing the hops, overdoing the alcohol content, and especially overdoing the number of ingredients. Nearly any type of malt or grain could be used in a robust porter, but that is not to say that all of them used simultaneously will produce optimal results. Before you begin planning your robust porter, take a moment to revel in the vast possibilities. Then take a step back and try to decide what flavors are really important to your vision.

Dark Grains

Dark grains are the heart of any robust porter. They should feature prominently.

Black patent malt is one of the darkest malts available. It has been kilned until it is the color of charcoal (~500°L). Although the reported color value can vary quite a bit between different maltsters. It provides much of the robustness that differentiates robust porter from brown porter. Black patent should comprise approximately 2 – 10% of the grist. Used with a light touch black patent malt will produce a subtle hint of complex roastiness. Used more generously it can produce a sharp acrid or burnt flavor. A little bit of this burnt-edge will prevent your porter from being flat and shapeless.

Chocolate malt is often used to increase the variety of roast flavors – tending more towards flavors of unsweetened chocolate. While less assertive than black patent malt, chocolate malt can be quite aggressive if overused. It is kilned to lower temperatures than black patent and it also comes in a range of colors (180-420°L). Usually it is a rich shade of brown (~300°L). Chocolate malt should comprise about 0 – 12% of the grist.

Black barley is superficially very similar to black patent malt. They have both been very heavily roasted (~500°L), but black barley was not malted prior to roasting. Black barley is thought to produce less of a sharp burnt flavor than black patent and have flavors more similar to coffee. In quantity it can create the perception of drying astringency. Conventional wisdom is that black barley doesn’t belong in porters, but several commercial examples buck this trend by including small quantities of it. Sometimes roast barley refers to a similarly unmalted grain that has been roasted to a slightly lighter color (~300°L), but for other maltsters roast barley refers to the same thing as black barley. The lighter grain has similar flavors to black barley. Black barley and roast barley in the same recipe might be redundant. If used either should be about 0 – 4% of the grain.

Black patent and chocolate malts can sometimes be found in a “debittered” form. These malts are made from barley that has had the husk removed before roasting. This greatly reduces the bitterness and astringency found in these grains as those flavors develop in the husk during roasting. Debittered malts can generally be substituted for all or some of the equivalent malt for a smoother porter.

Crystal Malts

Crystal malts add some essential sweetness to balance the dark roast grains. In addition to residual sweetness they help to create a rounder taste and full-bodied texture. Lighter colored crystal malts are generally perceived as sweeter while darker crystal malts have little bit of a sour bite sometimes compared to raisins, or plums. The darkest crystals have a little roast character as well. Medium crystal malts have more of a caramel flavor. Any of these flavors can work really well in a porter, but in most recipes it probably makes sense to choose one or two crystal malts to showcase. All crystal malts used should typically total about 5 – 15% of the grain bill.

Base Malt

Due to the strong tradition of robust porters in both the UK and the US, English or American 2-row pale malt are both safe choices for base malt. Slightly more characterful base malts such as British pale ale malt (e.g. Maris Otter) could be used. Pale ale malts will produce slightly nutty or malty flavors that can add a lot to a porter. Care should be taken as the extra flavors could come across as slightly cloying or muddled depending on the yeast strain used and your tastes.

Munich and Vienna Malts

While not traditional, many people like to use some Munich or Vienna malt when making a robust porter. The idea is to provide a big boost of malty flavor and aroma. This can compliment crystal malt flavors nicely and provide a middle note to bridge the gap between the specialty grains and the base malt. If using Munich or Vienna as an accent malt you want them to comprise approximately 0 – 20% of the grist. The truly bold might consider using either of these as their base malt. In this case, you might consider going light on the specialty malts in particular the crystal malts.

Amber and Brown Malts

Amber and brown malt are both lightly roasted forms of malted barley. They could be used to provide interesting intermediate flavors similar to Munich and Vienna malts. Amber malt is typically paler (~25°L) than brown malt (~65°L). Unfortunately, manufacturers are less than consistent with the terminology for these less than common malts. In spite of moderate color, these malts can be surprisingly bitter and astringent. A somewhat historical take on porter could use brown malt as base malt with little or no specialty grains. However, not all modern amber/brown malts have sufficient enzymes to self-mash.

Specialty Malts

Any of the following grains used in an otherwise simple recipe could work as a “secret ingredient” to add that little extra bit of interest. Special B malt, a type of extra dark crystal malt, could replace some of the other crystal malts. Special B imparts powerful caramel and raisin flavors typical of dark Belgian ales. Aromatic malt could be used as an accent-malt for an intense malt aroma. Biscuit malt could substitute for some of the base malt to produce a dry, toasted, bready undertone. Dark grains produce some of these same flavors so they should be used in moderation with biscuit malt. Special roast is a moderate-roast malt that is comparable in color, but not flavor, to brown malt. A moderate amount of special roast produces a sour twang that can compliment the sharp flavors from black patent.

Mouthfeel, head-retention, and body should not generally be problematic in all-malt formulations of robust porter. However, a little extra body could be needed where a lot of extract or adjuncts are used. The usual grains can be used to increase body: dextrin malt, flaked wheat, flaked barley, and rolled oats. Any of these could replace about 10% of the fermentable sugars or base malt without altering other flavors too much.

Adjuncts

Use of non-grain adjuncts is less common in modern renditions of robust porter, but traditionally saw some use. Historically, unscrupulous brewers used all manner of low-quality and even dangerous additives to cut costs and artificially increase perceptions of the beer’s potency. Modern homebrewers might consider playing around with sugar products such as table sugar, turbinado sugar, golden syrup, brown sugar, and molasses. The last two, brown sugar and molasses, are less refined and will contribute molasses flavors that can work quite well in a porter. The other more refined sugar products will add alcohol and allow for a less viscous beer if used to replace some malt.

Grain adjuncts such as corn were often used in Colonial porters in America. Similar to the sugar products this tends to reduce the beer’s body. Most modern porters brewed in the US seem to avoid the use of adjuncts.

Hops

For porter the hops should be substantially bitter but relatively less prominent than the malt. Traditional English porters typically used a single bittering addition to unobtrusively provide hop-malt balance. A more American take on the style is slightly hoppier and makes use of later hop additions and sometimes dry-hopping. The well-known English hop varieties Fuggles and Kent Goldings were probably used in the first porters. Less tried and true English hops – Challenger, Target, Brambling Cross – are also good choices and can offer some nice variation on the theme of English hop-character.

Clean bittering hops like Magnum and Galena can provide more of a “blank” bitterness. Some brewers enjoy the mint-chocolate effect you can get by using minty tasting hops like Northern Brewer or Perle.

For the more American-style, the Fuggles derivative Willamette has many flavors in common with English hops. Other US-grown variants of English hops are also available. There is some thought that strong citrus-hop flavors can be harsh or metallic when interacting with roast grain flavors, but some commercially-brewed American porters are thought to use citrusy hops like Cascade.

Yeast

Yeast should be an ale strain from the UK or the US. Strains with fairly high attenuation are a good choice due to the potential for excessive sweetness in this style. Strains that produce some fruity esters or ferment relatively cleanly can be used depending on your taste.

Water Profile

All grains make the mash more acidic. In dark roasted grains this effect can be even more dramatic. If the mash pH drops below the target range for enzyme activity then extract efficiency will be reduced. For this reason, very dark grains tend to work best in water that has elevated levels of carbonate. The carbonate ions help to neutralize the grain acidity and keep the pH in the correct range.

Mashing and Fermentation

Mashing at the low end of the temperature range (149-153°F) will help to reduce the risk of a cloying under attenuated beer. This allows you to put in strong malt flavors without making the beer seem heavy.

Porter just needs standard ale fermentation practice, a healthy yeast starter, and a steady temperature. It should be served with a medium amount of carbonation or somewhat lower than medium carbonation 2.0-2.5 units of carbon dioxide. Well made porter can have a substantial shelf life, easily lasting for nine months or longer.

References

^ Beer Judge Certification Program style guide 12b http://www.bjcp.org/2008styles/style12.php#1b
Colby, Chris. "Practical Porter." Brew Your Own December 2007. http://byo.com/stories/item/1260-practical-porter
^ Daniels, Ray. 2000. Designing Great Beers: The Ultimate Guide to Brewing Classic Beer Styles. Boulder: Brewer's Publications.
^ Fodor, Alex. "Robust Porter: Style of the Month." Brew Your Own December 1997. http://byo.com/stories/item/1327-robust-porter-style-of-the-month
^ Hibbard, Mark. "A Primer on Priming." 1995. http://hbd.org/brewery/library/YPrimerMH.html
^ Jankowski, Ben. "American Porters: Marching to Revolutionary Drummers." Brewing Techniques. March 1997. http://morebeer.com/brewingtechniques/library/backissues/issue5.2/jankowski.html