Blending is done 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 month to month and 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 various (or the least expensive) sources and attain a consistent flavor. 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 it's not likely you can do this with top coffees. 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 say 5 coffees in the blend. Blends with more than 5 coffees I consider fanciful, or indulgent.
Blending Before or After Roasting
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 on Monsooned coffees 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 temperature. 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.
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, a blend of coffees roasted to different degrees. A good reason for a Melange may be perhaps that you 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 roast flavors, good body, and an acidy snap to it:
If you want a Melange that has good body, good bittersweet flavors, but still has acidity, without the carbony flavors:
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:
I have found that our association trade show is 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 SCAA trade show in Philadelphia it was amazing how many Melange blends feature 30%-40% Kenya for acidy snap. 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.
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 acidic Mokha coffees from day one it seems. Was it only done by habit? Or was it done 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!
Mocha-Java can be interpreted literally, with Yemen Mokha and estate Java as the constituents. Or, as is usually the case, it is a blend of some Indonesian coffee (Sumatra or Sulawesi) with either a (dry-processed) Ethiopian or Yemeni coffee. They are commonly blended in equal parts 50-50, or with a little bias like 40-45 African, 60-55 Indonesian.
Traditionally, most espresso blends are based on one or several high quality Brazil arabicas, some washed, some dry processed (or pulped natural). African coffees are added for winey acidity or enzymatic flowery /fruitiness, or a high grown Central American for a cleaner acidity. The past few years have seen a shift in the approach to espresso blends and even espresso roasts, with brighter coffees and lighter roasts. The Espresso Workshop blends reflect this new thinking (more on this below).
Dry processed coffees are responsible for the attractive crema on the cup (crema is a result of other mechanical factors in the extraction process as well). Wet-processed Central Americans add positive aromatic qualities. Robustas, or coffea canephora, are used in some blends to increase body, produce crema and add a particular bite to the cup. The notion that true "continental"espresso blends have Robusta is 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. It's fun to play with Robusta but I personally don't like it too much beyond experimentation.
A Colombian-based espresso blend offers a sharper, sweeter flavor but won't result in as much crema production.
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,
and pulling straight shots of espresso. Get familiar with this cup and imagine
what you would like to improve in it (if you find it just fine as is,
then you have no need to continue!)
There you have it, the "Open Source" code for Classic Italian. Not that complicated, eh? Well, it comes down to a lot of work selecting the right coffees to optimize the cup quality and maintain consistency. That is the hard part my friends. If you want to build this blend yourself, just avoid sharp acidic coffees, avoid fruity coffees, and look for restrained, balanced flavor profiles. It will turn out well if you do ... -Tom
More Blend Recipes: Some Blends I Like
What coffees won't I use in espresso? A lot of this is changing too and sometimes now it seems that anything goes; people are using just about every origin either in espresso blends or as single origin (SO) espresso. Now it is not uncommon to see Hawaiian Kona as SO espresso, and a few years ago a competitor won the World Barista Championship with a SO Kenya.
There's a lot of ways to achieve great espresso. It's fun to experiment and I don't know if there is some terminal point where you achieve the perfect trans-subjective espresso. These recommendations reflect my biases, of course.
For benchmarks, I would recommend you try our Sweet Maria's Espresso Monkey Blend to see what you think. It will definitely give you a basis for comparison; it is a straight-forward sweet espresso blend. The Malabar Gold blend is a exotic pre-blended espresso, and if that's what you like, you might want to look into Aged coffees and Robustas for your own blends, and obviously you would want to be using Indian Monsooned Malabar. The Moka Kadir is a very fruity-winey North African and Yemen blend. So these three span the gamut of blends and can give you a good idea what direction to take with your own blend. Many people also buy my Espresso Monkey blend and modify it by, for example, adding 15% robusta or adding 25% Aged coffee.
Here's a great starter blend for a sweeter, cleaner espresso. The absence of North African or Yemeni coffee takes out a little bite from the cup and possibly some lurking fruity ferment flavor. This is, as noted above, a sweet blend used at a street level roasterie/caffe in Rome. They use a Guatemala Antigua for the Central:
I don't think Colombians really pull their weight in a blend (though many people use them as a base or part of their blends), and like using some Sumatra better:
Some sharp sweetness (Central American) hides behind the nutty Brazil flavors and the wonderful Yemeni aromatics. Mandheling adds body and depth. Yemeni coffees are fun for espresso blends, where they can be used like spice to give zest to aromatically or enzymatically flat blends. Roast to Agtron 40 to 35. Good crema production from this blend due to the many dry-processed coffees
Ah, too sweet, too boring. You want something more aggressive, chocolatey? Drop the Centrals:
You can certainly keep going along this route by adding other coffees (monsooned, aged, robusta) to discover what they add and what they subtract from the blend.
For an potent Indian Monsooned-type blend you could do something like this:
For an potent Aged coffee blend you could do something like this:
Decaf Espresso? Low-caffeine espresso? It is good to use the same regions in decaf form if possible - we do try to stock Brazil decaf for this reason (when possible). Use this as 50% of your blend to cut the caffeine in half, then add your main "character" coffees as usual. Decaf Ethiopian is excellent in espresso. Try 50% Sumatra Decaf and 50% Ethiopian Decaf for a fantastic decaf espresso blend! If you wanted an all-decaf blend I would do one of these:
For a half and half blend - just make one part decaf and the rest regular. Decaf coffees can lack some of the potency of their regular counterparts - so you may need to make adjustments to compensate. We also offer our own Sweet Maria's Decaf Espresso Blend ready to roast.
A New Approach to Blends (from January-February 2009 Tiny Joy)
After a lot of consideration I have decided to take two approaches simultaneously. I decided to change our blend offerings into Standards, blends with the same name we maintain and are consistently offered, and new Espresso Workshop editions. The latter are blends that are only offered for as long as we have the specific lots of coffee we used to design the blend, and then it's gone. It's a coffee-centric idea, and allows for the exploration of newer espresso styles. In a sense, Espresso Workshop editions are pure and uncompromising: specific coffees are found that inspire testing, and a new blend idea is born. Instead of maintaining the blend and making ingredient substitutions down the line, the Workshop editions follow the crop cycle of the coffee; they come and go. The current Espresso Workshop and Standard blends are both listed on the current offerings and the discontinued the Classic Italian and Puro Scuro blends which are now listed in the review archive. (Notes on how to mix these blends yourself appear above)