How do we determine coffee bean roast level?
One of the most common things we hear from people who love coffee but haven’t yet experienced speciality coffee beans is the phrase ‘I love strong coffee’ or ‘I like dark roasted coffee’. This always opens up an interesting discussion about the differences between light roasted coffee, solubility of coffee and flavour comparisons.
Firstly we know that tastes are very personal and some people do prefer dark roasted coffee. Generally speaking within the world of speciality coffee with high cupping scores and traceable microlots a light to medium roast is preferred. The reason for this is quite simply that a lighter roasted coffee allows the true flavours of the coffee to be appreciated. As coffee is roasted darker the flavours of the coffee roasting process start to dominate. Initially sugar browning will occur and caramel flavours are present but as the roast gets darker this is taken over by bitter, smokey flavours. Many coffee drinkers are accustomed to these flavours as the majority of supermarket coffees are roasted fairly dark. In addition, many of the chain coffee shops use dark roasted coffee. The ones that come to mind are Starbucks and Pret a Manger. Traditional northern Italian espresso beans aren’t actually roasted as dark as many people think. Costa roast their beans darker than we would but much lighter than some.
Determining roast level:
When we create a roast profile for our coffee beans we use a colour meter to determine how well we have developed the roast. The colour meter uses the Agtron scale for scoring. Most of our roasts fall into the region of 75-85 (a higher number is a lighter roast. Measurements are done using ground coffee). A lighter roast might suit an Ethiopian natural processed coffee while a roast at around 75 agtron score would be the target for our Workhorse blend. If you’d like to read a bit more about Agtron scores it’s worth having a look at some coffee reviews at www.coffeereview.com. Although it’s mainly US based roasters reviewed it’s very clear that the majority of the top scoring coffees have a ground agtron score of between 70 and 85. There are, of course, exceptions but this tends to be the sweet spot where the character of the coffee can still shine without roast flavours taking over. We recently colour scored a sample of Illy coffee and found that the ground coffee scored 65 on the Agtron scale, not as dark as some people might think! A score lighter than 85 might mean that the coffee is under-developed making it very difficult to properly extract The flavours of the beans wont be properly developed and grassy, vegetable green coffee flavours will dominate.
Strong coffee and solubility:
If you enjoy a full bodied, strong cup of coffee you can still use lightly roasted coffee beans but you need to ensure you brew correctly. The choice of coffee could make a difference too. Coffees from Brazil tend to have nutty, chocolate flavours with a muted acidity while coffees from Kenya and Rwanda will have a bright, juicy acidity. Solubility of coffee plays a big part too and it’s important to make sure you stick to a reliable recipe when making your coffee. If you under extract your coffee it will taste weak and watery but a light roast that is properly extracted is still capable of full bodied flavours. For advice have a look at our brew guides. Ultimately, once you’ve selected a recipe you can increase strength and body using one of the following three methods: Increase brew time, increase the amount of coffee used or grind finer. To test solubility we use a device called a refractometer, you can read more about these and the associated software on the VST website.
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