Jak v Coffee Source hodnotíme a pražíme kávu

How we evaluate and roast coffee at Coffee Source

Beginning of roasting at Coffee Source

The first idea to open our own roastery came when we were traveling around Europe. As part of these trips, the year was 2002, we visited an Italian friend who was selling coffee from his roastery in Sicily. At that moment, we started toying with the idea that this could be something we could enjoy, and at the same time we saw the potential within the Czech market. So we started taking coffee from him on the Czech market, but over time we found out that it wasn't quite that. That coffees have different tastes and we don't even have much to choose from. And here came the idea of our own roastery, where we could control both the roasting process and the resulting taste of the coffee.

How we choose the parameters of coffee roasting

He is the first roaster to check in the system whether he has not roasted this coffee in the past. If so, they usually choose the same or similar procedure according to the previous roasting. If it is a new coffee that has not yet been roasted, then according to the parameters of the coffee that it has available in our system, it will evaluate how approximately this coffee should be roasted in order to achieve the desired result.

What the roaster primarily cares about

Of course, it is important to roast every coffee perfectly and especially to make sure that no bad coffee leaves the roastery for customers. Coffee is generally a commodity that must be pampered and well processed. Its task is to extract the maximum from each grain within the roasting in terms of flavor component. If there were good samples, you can always create something out of it, but of course you have to have some experience. It should also be noted that each batch of coffee is unique.

The size of our roastery

Our roastery in Prague's Štěrboholy is adapted to 45 kg of coffee per day, however, we actually use only 2/3 of the capacity. This is mainly due to "waking up", when it is better to achieve shorter roasts, so coffee is roasted, otherwise there is "roasting" and the occurrence of unpleasant taste defects.

Volume of roasted coffee per day

At Coffee Source, we can handle 14 batches at a time during the morning and 14 batches in the afternoon, so we are able to roast up to 840 kg of coffee per day.

Coffee Source - káva

A normal day at the Coffee Source roastery

As soon as our armor comes to the roastery in the morning, he will evaluate what kind of coffee he has prepared for roasting. With the help of the system Cropster evaluates the parameters of the coffees waiting to be roasted and determines the order in which the coffee will start and which it must end. This depends on many variables such as the incorporation of coffee, whether it is BIO production, which must always be roasted first, and so on.

Once he has a set order, he sets the so-called drop temperature. The temperature at which the coffee begins to roast. The roasting process takes about 12 minutes, however, again it depends on the type of coffee, its hardness, humidity and other parameters shown to it by the system.

As soon as it reaches the dropping temperature, the coffee "drops" into the roaster. Now it monitors and evaluates the entire roasting process on the screen and corrects the roasting process according to the data. After years of experience, he already knows that as soon as he changes any roasting parameter, where the coffee is moved with the help of the most important roaster tool - a cupping spoon. The biggest guide for him is therefore the first coffee tasting, which we always do on samples before the actual delivery of coffee from suppliers.

Coffee Source - pražení kávy

Qualitative cataloging of coffees 

The determination of the dropping temperature and the subsequent correction of the roasting process is based primarily on previous experience that has been gained during previous roasting and it is also important to have some sense. In the case of coffees that have been roasted in our country in the past, it is possible to follow the previous roasting, however, new coffees are a learning process that our roaster must go through in order to gain new experience and roast this coffee correctly.

Electronic helpers help us with an overall overview of the quality parameters of not only raw coffee, but also roasted coffee, without them we would not be able to achieve such taste results. These are in particular:

Cropster Roast - an online platform that collects individual roasting data from Cropster Intelligence, which is an application, or rather a data bridge, converting an analog signal from temperature probes located at the roastery into a digital signal, and recording the roasting process in real time, data from this application they are synchronizing with Cropster Roast

Cropster Lab - is a part of Cropster and all samples of raw coffee are registered here, their parameters before sending from suppliers, so that they can be compared with the quantity sent from the farmer or trader

Cropster Cup - an excellent thing, which is used only for roasted coffee, as well as an application in smartphones and each cupper from the roastery has the opportunity to enter tasting data into their device, after the end just sync again and the online platform displays all the results, averaging points , of course, we have been quite calibrated in the years that we have been moving in coffee, but even so, individual coffees are subject to discussions and opinions on their scoring. We can thus return to the results at any time, analyze them retrospectively and have an overview of all roasted coffees, where the changed roast has moved, and so on.


Of course, there is still a lot to mention about roasting in our roastery, but you have already learned the basics. At Coffee Source, we treat you with professional care, we don't just give impressions, even though they are also important. It's a whole amorphous process that is constantly changing and also constantly smelling, and these are the things that keep us going with this craft.