One thing this article will not do is give you advice on times or profiles. Times vary wildly according to roast method, bean type, environmental temperatures, crop age, and the list goes on. Most home machines wont let you profile the roast (or will have a pre-set profile). But with these guidelines I hope that you will be able to come close to what I think is the desirable roast for each coffee we offer. The roasting notes are provided so that the characteristics of each individual bean are emphasised and the roast is not the primary feature. Of course, one of the joys of home roasting is that you can produce whatever degree of roast you want, and your tastes may prefer a certain profile, but this guide will give you a starting point to work from and explore the treasures within each bean. Roasting is something that comes with experience and there are no set rules to follow. That’s why this article has been so hard to write, so bear in mind these are guidelines, not laws or rules written in tablets of stone.

Before we get into the descriptions there are factors to bear in mind when roasting coffee that will have an affect on the roast.

Origin
Where the bean is from will have a major bearing on the way the roast behaves and looks. Some origins just look different after roasting, or look uneven. This can be due to processing (see below), the altitude the beans were grown at, main geographical areas, climates, soils, etc. one immediately thinks of the French concept as referred to in wine making, of “terroir” where each crop is truly individual. These factors really make a difference on the roast and taste produced from the coffee.

Processing
Wet, dry, naturally dried, machine dried, decaffeinated, monsooned and even from the rear-end of an animal (the civet cat eats the coffee cherry, digesting the fruit and “processing” the bean, before passing it on! Check out our Kopi Luwak). All have a bearing on the roast’s final appearance and taste. These are all important elements to remember when evaluating the final roast, both visually and in the cup. For instance monsoon coffee's are picked and then placed in shed like warehouses where the monsoon winds dry the bean. This effects the roast and taste dramatically because the moisture content and bean structure are changed by the process.

Length of Roast
The length of time a bean is roasted can have a profound effect on the taste. The roast profile is very important in achieving the best taste for each bean. Professional roasting can take around 15-20 minutes. Some “roasting curves,” or the speed and temperature at which the roast develops, differ quite drastically, and this can affect the final taste. This is provided more for information’s sake than anything else, as we at Has Bean worry about this and apply our skill and expertise in adapting the profile for each different coffee. These roasting curves are mimicked by some of the more semi-professional home roasters (Hottop, I-Roast and the Alpenrost).

Roast Method
It is a commonly held view that gas roasting gives a different finish to the bean during the roasting process, when compared to roasting with electric machines. To which one could add that hot air roasting and drum roasting give different results too, and these are also important factors to consider. Drum roasting tends to give more fuller bodied roasts, but lacks the brightness that an air roaster can give. The air roaster can also give a more matted appearance on the bean.

Age of Green Beans
As coffee ages it loses some of its water content. As the bean dries, its structure (taste and behaviour in the roast) changes. Of course, this can be avoided by stocking fresh greens from a roaster who has a large turnover of stock, and who doesn’t hold onto old stock. Should this happen to you, then be aware that what worked when you first bought the bean, may not work the next time, if the bean has aged considerably.

It is also important to understand what happens when coffee is roasted. Coffee as a green bean has no use, and is unpleasant to taste. When roasted, coffee releases over 800 components that build up its taste and flavours. This makes coffee one of the most complicated foods around, and such an unique organic product.

The roasting process removes water from the green bean, makes sugars caramelise, and sparks a series of reactions that produce those 800 components in coffee oils, either within the bean, or on darker roasts, on the outside of the bean. These reactions also create carbon dioxide, which in the first couple of days is present in incredibly high levels making the cup too lively due to the CO2 in the bean (this can vary from bean to bean, and be between 24 hours and 6 days). So a period of rest and degassing is important if you want to get the best from your bean. Without any carbon dioxide, coffee loses all of its taste, as once de-gassed the carbon dioxide acts as a delivery vehicle for the flavours, so achieving perfection is a very fine balancing act. As a general rule, darker roasted beans tend to de-gas quicker than lighter roasts, which will de-gas and be at their peak after a number of days. Also, lively coffees that haven’t had long to de-gas can sometimes be a joy in a french press or vac pot, but for an espresso lively isn’t normally a good attribute.

During the roasting process the guidelines we will use are called first and second “crack.” The reason I choose to use these terms over specific times, is that from one type of roasting device to the next, the roast time can differ from either a couple of minutes to 25 minutes. Temperature, although useful as a guide, can vary, and it is difficult to get an exact reading between bean temperature and the temperature of the surrounding environment of the roasting machine.

First and second crack are sure signs of roast development. First crack is an expansion of the bean and a warming of the coffee oils, creating an exothermic reaction, which means the beans are giving off heat as a consequence of their expansion. This results in a popping noise similar to that of popcorn. Second crack sounds more like a crackle, similar to the sound of foil rattling. I’ve heard audio files of both first and second crack, but I don’t think they are that useful, as different beans in different machines, will all sound slightly different. One thing to beware of is, sometimes, first and second crack can merge into each other. It’s important to listen intently during these stages.

Descriptions:

Into First Crack (Light Roast)

A light brown to cinnamon colour, low body and light acidity. The beans at this stage are dry. This roast restricts the coffee’s development and does not allow it to reach its full potential. Some moisture has been released, but the important coffee oils have yet to develop fully. The bean is in the very early stages of being exothermic (creating heat by expansion).

End of First Crack (light medium roast)

Medium light brown colour. The acidity has brightened and body has increased. At this stage the bean is releasing coffee oils and becoming much more like what we know as coffee. A suitable cupping roast. Also suitable for many “delicate” beans.

In-between First and Second Crack (medium roast)

Medium brown colour. The acidity continues to increase and the body becomes more noticeable. At this stage the bean is mostly dry. A popular roast for “delicate” beans, suitable for many filter type blends/origins, and one of my favourite roasts. Beans are still exothermic and the structure is on the verge of expanding more as the coffee oils heat up and second crack is on its way.

Start of Second Crack. (Medium Dark Roast)

Rich brown colour. Very small droplets of oil appear on the surface. The acidity has slowly diminished and body is at its best. This is the perfect roast for espresso blends and can be compared to a Northern Italian espresso roast, as favoured by many professional espresso blenders. Second crack has begun and the structure of the bean is starting to break down, and from now on there is a balancing act to perform, in order to keep the integrity of the bean as the primary taste and the roast secondary. This is my favourite roast for espresso, and although it is often described as a Northern Italian roast, in our new easy world of descriptions, we will call it a medium Dark Roast.

Well into Second crack. (Dark Roast)

The bean is a deep brownish/black shiny colour. The bean has spots of oil or is completely oily. Delicacies are lost and the roast taste begins to increase and aroma begins to diminish. This roast can give certain beans real body, when used correctly. When we say well into second crack, I guess we are talking anything from 20 seconds onwards. In the roast descriptions I will try to give some indication of time.

Fully into Second Crack (Exceptionally Dark)

Black beans covered with oils. All subtleties are gone and aroma is reduced further. This roast is characteristic of Southern Italian roasts and of American espresso roasts. The roast has become the primary taste for sure, and the bean’s characteristics have been completely demolished. There are very few beans that stand up well to this kind of roast and it should be used with extreme care.