Roasted coffee beans are the main element that will influence the quality of your coffee. At the moment of roasting, the coffee bean brings out all the characteristics that will end up in your cup. A great cup of coffee results from the natural roasting of the coffee bean.
In natural roasting, the only manipulation the coffee bean undergoes is the application of heat in the roaster until the desired roast point is achieved. In other words, the coffee has not been mixed with anything. There is only the bean, a heat source and the roaster’s hand to bring out all the quality the bean has inside.
During roasting, the beans will undergo a series of modifications in the structure and changes in physical and chemical properties.
The most noticeable changes in a roasted coffee bean
Weight loss
The bean will lose between 15 and 20% of its weight to the green coffee that goes into the roaster.
Gas formation
During roasting, coffee forms CO₂, between 5 and 12 litres per kilo of coffee. This is why we do not recommend consuming freshly roasted coffee. Ideally, it is best to wait a few hours for it to release these gases completely.
For this reason, packets of coffee beans are packed in bags with a gas release valve. This valve allows the gas to escape to the outside, but no air enters the packet. Or they wait until after a couple of days, the gas has disappeared, and the valve is no longer needed.
Interestingly, once the gas is gone, it’s best to consume the coffee as soon as possible. Coffee loses aroma and flavour as the days pass after roasting, so it is best to consume it as soon as possible after packaging.
Increase in coffee bean volume
The gases above and the water vapour increase the pressure inside the bean, causing it to swell. This allows the bean to grind more easily when roasted.
The porosity of roasted coffee beans
The bean becomes more fragile and brittle when roasted. This will aid in the exudation of the coffee and the extraction of soluble compounds that are responsible for the aroma and flavour of the coffee.
The appearance of coffee beans after roasting
Beans turn from green to a brownish, light brown, deep brown or approaching black colour. This colour change will depend on the type of roast applied. I do not recommend dark or very dark roasts.
Aroma
During roasting, volatile chemical compounds are formed, i.e. they disappear over time.
Caffeine loss
Approximately 10% of the caffeine is lost during roasting. This happens more in dark roasts and less in light or cinnamon roasts.
Acidity
Acidity decreases with roasting. The higher the roasting point, the lower the acidity.
Bitterness
The higher the roast, the more bitter the coffee. This is all good, but why prefer a coffee bean over a ground coffee?
Why is it better to buy coffee beans rather than ground coffee?
Because it is true that to get a cup of coffee, we will have to grind coffee anyway. And here, it is important to go for coffee beans.
One of the reasons is in the last lines, roasted coffee beans bring out volatile compounds that the beans did not previously have and are largely responsible for the aroma and flavour of the coffee.
What happens is that, with good packaging, a coffee can last a few days without losing aroma and flavour; once ground, these compounds dissolve more quickly, and many of them will have been lost even before packaging.
Therefore, if you want coffee with all the aroma and flavour, it is best to buy coffee beans, consume them as soon as possible, and store them safe from light, oxygen in the air and humidity, which are their greatest enemies.
How can naturally roasted coffee beans be preserved? The cold is a preservative, so storing it in a cool, dry place away from humidity is best.
The fridge would be an option, although I don’t recommend storing coffee there, as coffee absorbs moisture and odours very quickly, so the smell of other foods in the fridge will end up in the coffee.
Coffee traps those odours immediately; if you have problems with the smell in your fridge and have very stale coffee, you can use it to eliminate them.
It is better to grind the coffee in small quantities and consume it immediately once it has been ground, just as they do in any coffee shop.
Freshly ground coffee retains all its aromatic and flavour properties. Grinding it immediately means that you start to enjoy the coffee before you drink it. It’s a very interesting aromatic experience.
What is the other big reason to buy freshly roasted, not ground, coffee beans?
We need the water to extract all the properties of the coffee, and if it is in bean form, we will not be able to achieve this.
Each extraction system, if you prefer a coffee machine, has different requirements regarding the degree of grinding.
Coffee can be coarse, medium or finely ground, but the one you choose is crucial because the coarseness determines how long the coffee bean is ground with water, resulting in a better taste and texture.
You should also keep in mind that each type of coffee maker needs a precise grind, and it is essential to choose a good coffee grinder that does not increase the temperature of the coffee while grinding.
Consistency is key when it comes to grinding coffee beans.
The consistency you need depends on how you want to prepare it. The finer the coffee, the less resistance there will be for the liquid to extract the flavour, but this is not necessarily the best, as your coffee could become too bitter or intense. Certain consistencies work better with specific brewing methods.
French presses coffee makers
Coarse grind. The grind mustn’t be too fine, or part of the grind may go through the filter of these coffee machines.
Drip coffee machines
Medium grind. In this case, the grind is perfect. We can use this type of coffee without any problem in these coffee machines.
Moka pots
Fine grind. But not as fine as in espresso machines. The coffee does not have to be pressed in the coffee machine (contrary to the espresso machine).
Espresso coffee machines
Fine grinding. The best thing to do is to grind the coffee beans yourself. You will need a good quality professional grinder to achieve this.
Turkish coffee machines
They need an extra fine grind, real coffee powder; that’s why Turkish coffee is so strong.
Avoid a blade grinder when grinding coffee beans.
According to experts, grinding coffee with a blade system will not have the best result because it gives an irregular result and conforms to a universal grind.
This means that it will leave coarser particles than others, and you will not be able to choose the type of coarseness for the coffee machine you have, resulting in a very unbalanced drink.
Burr grinder: Conical or flat?
It is best to choose a coffee grinder with burr for a more precise grind, although it can be conical or flat.
Manual grinders are available for a few pounds, but if you want a professional grinder, prepare your bank account as they are very expensive.
The taste of your coffee not only depends on the type of grind but is also influenced by the brewing temperature and the time it takes to prepare the coffee.
- If there is too much coffee extraction, you will get a cup of coffee that is bitter and lacking in flavour.
- If there is too little coffee extraction, you will get sour, acidic, and even salty coffee.
Of course, if you buy ground coffee, it may not have the exact consistency of grind that your type of coffee maker requires.
And if you make coffee with a coffee machine and a coffee grind that doesn’t match it, the result will never be good.