Sweetness in Coffee

Last Friday I had the pleasure of presenting the topic of Fair Trade coffee to several mid-sized groups of mid-sized individuals at Glashan Public School.  I was one of a number of presenters – mostly representing NGOs –  invited to start a dialog amongst the grade 8 students about all things global, frightening and worth remedying through conscious action.  As part of my effort to communicate the difficulties faced by farmers in the conventional coffee trade I was speaking to the notion that trading in quality coffee is the most important decision a producer organization or, in our case, a retailer can make if that want to see sustained profitable green coffee prices for farmers.  That topic certainly is worthy of a post to call its own!  Anyhow, I quickly elaborated on what makes a ‘quality’ coffee and among my descriptions the argument was made that quality coffee ought to be sweet.

That coffee should be sweet seems fairly elementary to me, however upon fielding a follow-up question from a keen elementary student insisting that “coffee isn’t sweet” I realized that it’s very likely my understanding of coffee has strayed a little from the norm.  In an effort to correct that, I’ll try to briefly elaborate on what I know about sweetness in coffee.

We generally don’t regard coffee as being sweet for two reasons.  Firstly, the coffee we’ve traditional enjoyed over the decades in North America has been of very poor quality both in terms of the quality of the raw product and the quality of preparation.  Secondly, for most of us our first introduction to quality coffee in North America generally involved dark roasts which have no sweetness.  I’ll briefly speak to what I know about all three of these factors in determining a coffee’s sweetness:  the green coffee, the roast, and the preparation.

To begin with the raw product – green coffee contains many sugars, the most important of those in sweetness perception being sucrose.  Although I don’t know quite as much as I’d like to about the ability of artisan coffee farmers to increase the concentration of sugars in their coffee, there are a few general rules.  The first is actually quite simple:  the more perfectly ripe cherries present in the finished lot, the more sweetness.  Sugars develop extremely quickly in the final stages of ripening so ideally we’ll see only deep red cherries in a picking selection.  Beyond this altitude and, coincidentally, temperature play a significant role — my understanding is that low, stable temperatures result in long maturation periods for the cherries.  The longer is takes for the cherries to mature (say, 7 months instead of 5?) the more dense in sugars the coffee will be.    Lastly, I’ve heard it’s also possible to manipulate sugar production and storage through careful management of shade.

Cherry ripeness is extremely important for quality coffee. Here we see pre-harvest cherries at Finca La Estrella in Jinotega, Nicaragua.

Again, I’d like to know more about this than I do — but the point is that not all coffees have the same quantities of sugars, and the careful work of farmers is what gives us “sweetness potential”.

Moving along — the roast has a significant impact on sweetness in coffee.  Roasted coffee’s aromatic character mostly comes from sugar-derived volatile molecules.   These result from three distinct reactions —

  • Caramelization (the breakdown of complex sugars like sucrose into simpler molecules, usually with an aromatic molecule as a product)
  • Maillard reactions (those reactions between amino acids and reducing sugars)
  • Strecker degredation (which I believe is simply the reducion of amino acids into aromatic aldehydes)

As you can see, two of these three processes involve the destruction of sugars!  On the bright side we get extraordinary aromatics (I just finished a cup of Nicaraguan coffee that tastes distinctly of honey and hazelnuts, among other aromas), but as we create flavour we lose sweetness.  A light roast may contain about 3% of its original sugars, remaining quite sweet if there was a lot of sugar to begin with.  A medium roast will have closer to 1% of its original sugars — potentially still quite sweet if there was a ton of sugar in the coffee to begin with.  Dark roasts have no sweetness at all – the sugar is all gone by this stage of roasting.

Lastly, preparation matters a great deal when it comes to finding sweetness in coffee.  You can take an incredibly sweet coffee and present it with no sweetness at all by fouling up the brewing process.  Generally speaking underextracted coffee will be sweet but will be greatly imbalanced by excessive acidity and sourness.  Overextracted coffee will have dulled or null sweetness depending on how badly overextracted it is.  Sweetness tends to peak when you evenly extract about 19%-19.5% of the ground coffee mass and I find it generally disappears once you extract more than about 20.5%.

To experience sweet coffee, first choose a light to medium roasted coffee of high quality.  You can use “specialty grade” as an indication of the coffee’s quality, although it’s also very important that the coffee is freshly roasted, ground and properly roasted.  Secondly, make sure the coffee is expertly prepared!  If you’re not buying it at a quality focused coffeeshop, check out BrewMethods.com for home brewing tips.  Next, don’t put anything in it!   It’s a little difficult to enjoy the intrinsic taste qualities of a coffee behind the mask of cream and sugar!  Lastly, wait for the coffee to cool a bit as most moderately sweet coffees are most enjoyable after they’ve sat in the cup for a good 5 minutes or so.

If you’re in a Bridgehead on the day of this posting, most of our shops are brewing a coffee from Papua new Guinea as the “medium roast”.  I’ve always found the aromatics on this coffee a little though to nail down — it’s certainly berry-like in a blueish sort of way with some toasted nut and vanillic aromas.  While the aromatics are a little vague, this coffee is fairly sweet in a way that resembles the unprocessed sugar that you see on our condiment counters.

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