Blending Coffee: Espresso Blending, Dark Roast Blending, Filter-Drip Blending
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Blending Basics
Coffees from different origins are blended together for several reasons. Presumably the goal is to make a coffee that is higher in cup quality than any of the ingredients individually. But high quality arabica coffee should be able to stand alone; it should have good clean flavor, good aromatics, body and aftertaste. So one reason coffees are blended in the commercial world might be the use of lower-quality coffee in the blend. Another reason might be to create a proprietary or signature blend that leads consumers to equate a particular coffee profile with a particular brand image; consumers don't often call Starbucks by the origin names used in the coffee but simply as "a cup of Starbucks" as if the dark carbony roast tastes were somehow exclusive to that brand. Coffees are also blended to attain consistency from crop year to year. This is done with major brands that do not want to be dependent on any specific origin flavor so they can source coffee from the least expensive sources. Such blends generally reduce all the coffees included to the lowest common denominator. But let's put aside the less-than-noble reasons that coffee is blended and focus on details that concern the quality-oriented roaster.
Before blending any high-quality coffees you should know the flavors of the individual coffees and have some goal for an ideal cup that cannot be attained by a single origin or single degree of roast. It would be a shame to blend a fantastic Estate coffee ...after all, you are supposedly trying to attain a cup that exceeds the components and its not likely you can do this with top coffees. And given that you have both a reason to a blend and a logical process for doing it, there will be little need for more than around 5 coffees in the blend. Blends with more than 5 coffees are considered to be fanciful, or indulgent, or confused by more than a few expert coffee tradespeople I know.
The Case Not to Blend
While blending requires the expert skill of knowing each ingredient coffee, having a clear cup profile as the goal in mind, and knowing how to achieve it, blends should not be considered a "higher" form of coffee by any standard. As indicated above, the opposite case is often true. For me personally there is much more satisfaction in enjoying single-origin and estate coffees roasted to their peak of flavor. In my opinion, even a so-so single-farm coffee is more intriguing than a blended cup ...even if the blend is admittedly superior! Why? Because when I taste an unblended coffee it is the end result of a long road from crop to cup, without any one person deciding what I will be experiencing. While I enjoy that cup, I like to think about that process, and it informs my opinion about that region or that specific farm. I enjoy feeling connected to the origin of the coffee and the process in this way...
Blending Before or After Roasting
I get a lot of questions about blending before or after roasting ...which is better? Well, if you have an established blend it certainly is easier to blend the coffee green and roast it together. If you are experimenting with blend ingredients and percentages you will want to pre-roast each separately so you can experiment with variations without having to make a new roast with each change. The case for roasting coffees individually is strong with the Melange type blend (see below) and with a handful of particular coffees, such as Robusta in espresso blends. Some coffees are more dense, or have extreme size variations. These will roast differently than standard wet-processed arabicas. All dry-processed arabicas require roasting to a slightly higher degree of temperature. But in most cases the coffees can be roasted together and I would advise this: roast the coffee together until you encounter a situation where the results are disappointing and for success you must roast them separately. Every coffee roasts a bit differently but there is a great deal of averaging that occurs between coffees in the roast chamber, especially in drum roast systems. And then there's the coffees that do not roast evenly as single origins either: Yemeni, Ethiopian DP coffees, etc. Uneven roast color is not a defect, and only when it occurs in a wet-processed arabica that should roast to an even color (and sometimes not even in this case) is it of any consequence.
Blending for Filter-Drip Brewing: the Melange
One of the most compelling reasons to blend coffee is the Melange. This is a blend of coffees roasted to different degrees of roast, so they must be roasted individually. In particular, you may want the carbony flavors of a dark roast but also want the acidy snap of a lighter roasted Kenya or Central American coffee.
Here's an idea for a blend that has dark roasts flavors, good body, and an acidy snap to it:
40% Colombian Tuluni roasted Full City -to preserve body (var. other Colombian, Nicaragua La Illusion, or perhaps Brazil Monte Carmelo)
30% Mexican Tres Flechas roasted French -for sharp, carbony flavors (var. other Mexican)
30% Kenya Estate roasted City -for bright acidy snap (var. bright Costa Rican or other Central American)
If you want a Melange that has good body, good bittersweet flavors, but still has acidity, and without the carbony flavors:
60% Colombian roasted Full City
40% Kenya or bright Central American roasted City
With a really good Central American that has nice balance, acidity and body, you can even blend two roasts of the same coffee with each other:
60% Colombian Tuluni, or Nicaragua La Illusion, etc. roasted Full City +
40% of the same coffee roasted City, just past the finish of first crack.
Our association trade shows are a great place to taste popular blends that are showcased by bigger roasters (they pay to serve their coffee between seminars) and taste what some roasters consider as benchmark quality blends. At the 1998 Specialty Coffee Assoc. (SCAA) trade show in Philadelphia it was amazing how many Melange blends that feature 30%-40% Kenya for acidy snap were put forth. It's an easy way to create dimension in the cup, and highlight acidity against the depth of bittersweet roast tastes and better mouthfeel (body) than Kenyas normally exhibit.
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Blending for Filter-Drip Brewing: the Mokha-Java Blend
It is provocative to contemplate the fact that blending is as old as domesticated coffee production itself. The full body, low-toned Java from Dutch estates was combined with the medium-bodied, enzymatic (floral-fruity), more acidy Mokha coffees from day one it seems, and those were the only two coffees in existence. Was it only done by habit? Or was it done solely to improve taste, the fact that the two complimented each other and resulted in a more complex cup than either provided by itself. With the crude roasting and brewing devices of the time, isn't it amazing that they could taste the improved complexity of the Mokha-Java blend! It's not difficult to take 2 excellent coffees and make an decent blend from them. Much commercial blending occurs to improve the "cup quality" of a coffee made from soft, uninspiring coffees or defective coffees.
The original blend, the Mokha-Java, with Yemen Mokha and estate Java as the constituents. Mocha-Java can be interpreted literally, or, as is usually the case, as a blend of some Indonesian coffee with either a Ethiopian or Yemeni coffee. They are commonly blended in equal parts 50-50, or with a little bias towards the Indonesian, like 40-45 African, 55-60 Indonesian. We have had excellent results with blending our Yemen Hirazi or Dhamari, Ethiopian Harar and either Sumatra Batak Mandheling (washed) or Sulawesi Toraja (washed).
Harar 50%, Sulawesi 50% brought to a City Roast (last dry stage before oil appears): Excellent delicate version of the Mokha-Java blend, with a wonderful floral aroma, fruity acidity, and a medium-full body. Java is the cleanest Indonesian coffee we offer, and the most nuanced. This is a superbly complex cup, that alternates between its low tones and the fragrant high notes.
Harar 50%, Sumatra 50% brought to a deep Full City roast: A more aggressive Mokha-Java, with a deeper, fuller body, and more earthiness in the bass notes. The roast's bittersweet adds to the complexity, and reduces the lovely Harar acidity somewhat.
Harar 50%, Sulawesi Toraja 50% : The cleaner taste of the Sulawesi vs. the more aggressive Mandheling results in a better, more focused blend. Sulawesi provides a better backdrop to the Hair's enzymatic flowery aromatics.
Yemen 25%, Sulawesi Toraja 75%: By far the best Mokha-Java blend, the Mattari is a great coffee to use almost as a spice ...it is so powerful that straight roasts of it can be a little "too much" for me. The Sulawesi provides a syrupy body and deep tones, the Hirazi just sits atop that and "does what it does", berry-like fruitiness and intense aromatics.
Ethiopian Djimma 15%, Harar 35%, Sumatra 50%: Djimma less acidy and bright and more chocolate and earth. It swings the blend in that direction...
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Espresso Blends
In general, the goal of espresso blending differs from the goal of filter coffee blends (and some may argue that there are blends specific for French Press brewing or for serving with cream/milk). Filter coffees may be blended for complexity or for balance, but an espresso blend usually must be blended for balance or particular varietal qualities that would be favorable in a filter coffee brew might overwhelm the espresso extract.
Most espresso blends are based on one or several high quality Brazil arabicas, some washed, some dry-processed. They often involve some African coffees for winey acidity or enzymatic flowery /fruitiness, or a high grown Central American for a cleaner acidity.
Dry processed coffees are responsible for the attractive crema on the cup, among other mechanical factors in the extraction process. Wet-processed Central Americans add positive aromatic qualities. Robustas, or coffea canephora, are used in cheaper blends to increase body and produce crema and in a few decent blends. They add crema and a particular bite to the cup. The notion that true "continental"espresso blends have Robusta. Nonsense! In fact the coffee samples from small Italian roasters I have (in green form) appear to be very mild, sweet blends with about 40% Brazil Dry-process, 40% Colombian and 20%+ Centrals, like Guatemalan. For bite and earthiness you can use a DP Ethiopian like Sidamo or Djimma. Its fun to play with Robusta but I personally don't like it too much beyond experimentation and I personally don't enjoy having more caffeine in my coffee than is necessary,
A Colombian-based espresso blend offers a sharper, sweeter flavor but won't result in as much crema production. Here are a couple interesting espresso blends we have fooled around with.
Either you can blend by the seat of your pants (not recommended) or make your process of establishing the coffees and the percentages logical. Start by developing the base, the backdrop in terms of flavor and a coffee that provides the kind of body, roast flavor and crema you like. I suggest Brazils, although Colombian or Mexican are viable options.
Practice roasting this base coffee to different degrees of roast, and pulling straight shots of espresso. Get familiar with this cup and imagine what you would like to improve in it (because if you find it just fine as is, then you have no need to continue!)
Do you want it to be sharper and sweeter, with more aromatics: perhaps you will want to add Central American coffees. Watch out with percentages above 25%, particularly if you like a lighter espresso roast. You will be losing some crema and body.
Do you want more body and sweetness: use a clean Indonesian like a Sulawesi or a premium Sumatra. You will be losing some sharpness. You can go up to 50% with one of these ...heck, they are nice at 100%!
Do you want an earthy aggressive bite and more pungency: try a dry-processed Ethiopian. Harar is brighter and more aromatic with fruitiness and ferment. Sidamo has great pungency in the darker roasts, fruitier in the lighter roasts. Djimma is not so fruity and less bright but adds earthiness. These produce great crema. I often enjoy straight shots of these coffees, but keep it to 25% or so in most blends.
Do you want spicy pungency: try a Yemeni coffee. These add ferment too, and great crema. I keep this to 50% or less (normally 25% or so) in blends.
Do you want extreme bite: try an Aged coffee, a Monsooned coffee (Indian or better yet the Sulawesi Rantepao) or Robusta. Aged coffees and Monsooned add certain funky tastes that you will love, or perhaps hate. You just have to give them a try to find out but that is part of the fun. Robusta --- I would not go there unless you have too. I personally do not like the added caffeine they bring. They increase crema, but you also need to keep them below 20% in the blend, I personally never go above 15% with them. The Monsooned Robusta can get up to 25% it seems... Arabica vs. Robusta? Arabica coffees (that means every coffee we sell except those at the VERY end of our list under the Premium Robusta heading) produce a fine crema, with good aromatics, and a lighter brown-yellow color. Robusta coffees (from the species coffea canefora) make a greater volume of crema, but it has larger "bubbles" and dissipates faster. Robusta has about 2x the caffeine of arabica, 2.2 to 2.4% compared to 1.1 to 1.3% in arabica. It can have a very rubbery-medicinal flavor when there is too much in the espresso blend. At a low percentage, 10% to 15%, it delivers a nice bite and it's negative features can be minimized.
