Understanding Coffee roasting - Different roast levels and choosing your coffee roast level

Posted by Ashish Dabreo on

Roasting a batch of coffee takes 11 to 14 minutes - but there are hundreds of chemical reactions, compounds, flavours, aromas and textures produced.

1. Green beans. 

Technically not all green beans are well, green. Depending on the way they’ve been processed (Washed, Natural, Pulp / Honey, Monsooned etc.) they could appear deep pale green to a very light brown or whitish. Green beans - harvested once a year - are stored in cool, well ventilated spaces that are shielded from moisture or extremes in temperature. At Maverick & Farmer, for most our roasts we load green beans into the roasting machine when the internal temperature of the machine is at about 200 C. 
You can order our green beans if you have access to a roaster or if you would like to experiment with simple home roasting.

2. Turning pale yellow

A few minutes into roasting and the green beans begin to lose their colour. At this stage, the moisture in the beans is quickly evaporating. Green coffee is normally dried to a moisture content of about 8 - 12.5%. During this stage the coffee beans begin to smell grassy and earthy, while the internal temperature of the roasting machine which rapidly dropped to about 70-80 C is now beginning to rise. 
coffee Roasting machine view hole

3. A very light brown

At about 140 - 150 C one can start to see traces of the familiar brown colouring of the roasted coffee bean. Along with this comes another sensory treat that is a favourite at the Maverick & Farmer roastery - the smell of freshly baked bread. All our daily roasting begins early-ish in the morning and we’ve invariably got a cup of freshly brewed coffee placed on a table nearby. Add to this the fragrance of freshly baked bread and you can only imagine why a coffee Roastmaster’s mornings are such a joy! The aroma of baked bread that emanates from the beans at this stage is probably because of the yeasts (inactive) present in the coffee beans or a combination of that and the browning of sugars and other carbohydrates in the bean. We’re not sure. We’re not complaining :)

4. The browning stage. 

At 160 - 170 C the brown colour of the beans deepen, and for us this is also probably the most important part of the roasting process, because during this stage a reaction called the Maillard reaction starts to take place. The Maillard reaction is the reaction between reducing sugars and the amino acids present in the coffee. Simply put, when this happens a whole range of distinct flavours and aromas are produced that puts the love into the final coffee cup. The Maillard reaction has to be handled with care and at the same time harnessed to produce great results - something that only experienced roasters are able to do (read - ‘us' ;) )

5. The first crack - Cinnamon roast

Right upto this stage there has been a steady pressure build-up within the bean due to the formation of gases and water vapour that just can’t wait to break through the surface of the bean. During the roasting process there are 100s of little chemical reactions that take place, each creating their own by-products (compounds) or gases. At a particular point during roasting (normally between 175 - 185 C for most of our beans) the surface gets brittle enough to allow the gases to break through (with a loud crack for good effect) and this is called the First Crack. At this point the coffee beans begin to be consumable. 
The characteristics of the coffee that has just attained it's first crack are pronounced acidity, clarity of origin, floral or fruity (berry, citric) notes and a medium to light body.

6. Light roast

A few moments past the first crack under highly controlled temperatures is when we get to the light roast. This roast is in the middle stages of caramelisation (which began after the Maillard reaction), and holds on to the origin notes of the coffee bean beautifully. Sweetness is still not pronounced but is present. At this stage (and beyond), all the senses of the roaster have to be on alert as tiny changes in bean characteristics contribute to altered flavour and cupping notes of the coffee. 
Our light roast coffee Say Hello To Mellow is a beautiful, delicate single estate Arabica. 

7. Light City roast

Nearing the end of the first crack, there is high bean development at this stage. The beans are now back to undergoing an endothermic reaction (taking in heat as opposed to an exothermic reaction at the start of the first crack). The sweetness is slightly more pronounced and a medium body is presented in the brew. Origin characteristics are clear and acidity is now beginning to appear reduced. 
Our Light City Roasts are Clouds In My Coffee - a monsooned malabar Arabica and  Orange You Curious, a microlot experimental coffee.

8. Medium roast / City + roast 

The biggest challenge in creating a good medium roast is ensure a beautiful sweetness while retaining some of the acidity and fruitiness and very importantly the origin characteristics of the coffee (the work that the coffee farmer has put into making his or her coffee so good). This is the result of what we’d like to call perfect 'hand-eye+nose' coordination - when it looks perfect and smells just right your hand should quickly go to the coffee release handle that removes the coffee from the roasting drumming. A few seconds here and there, and things could go awry. 
Our medium roasts are Parama (one of our most loved coffees) and a microlot called Milk & Honey

9. Medium dark roast / Full City / South Indian Roast

This roast is well into the first crack. Development of the bean continues and chocolatey notes start to become more pronounced. The body of the coffee is probably at it’s peak here and acidity begins to taper. While origin notes are not pronounced (still present though), this roast has more of what we call ‘coffee - coffee’ flavours than any other. 
The Rohan Bopanna Masterblend, Deepbliss and Sunkissed are our Medium dark roast coffees.

10 Full City + / Vienna Roast

After a while the coffee beans now begin to crack for the second time. The second crack sounds like a quick spell of rainfall, softer than the first crack but a lot more together. Tiny drops of oil are now beginning to form on the surface of the bean. Immediate stoppage (and cooling) of the roast now will ensure a proper Vienna Roast. Tasting notes of bittersweet coffee-coffee flavours, Roasty character and an eclipse of origin notes are prominent features of this roast. 

11 French Roast

A generous few seconds past the Second Crack is when the French Roast takes form. At this stage the beans are reasonably shiny because of the thin film of oil on them. The oiliness of a French Roast gets more pronounced in a few days after the roast. Many people like this roast because of a ‘Rich’ taste and the heavy caramelised sugars. There is a smokiness to this coffee and the body is now really thin since most of the soluble solids are burnt out by now. Acidity is almost non-existent in a French Roast and caffeine levels are at their lowest. Did you know caffeine is actually at it’s highest in a light roast and it steady begins to get cooked out after that?
Our French Roast arabica coffee is Tall Dark & Handsome

12 Super Dark / Dial 101 for fire.

Post the French Roast, for those that dare to venture beyond (and we do have a few cafes that order this) is the Super Dark roast. The coffee beans (if you can still call them that) are now almost carbonised and thick fumes of smoke billow out of our exhaust systems. On the one occasion we reluctantly cupped / tasted this coffee, we experienced notes of ash, charcoal and a wee amount of coffee flavour. 

Share this post



← Older Post Newer Post →


Leave a comment

Please note, comments must be approved before they are published.