The fourth wave of coffee

Let’s examine the most significant changes that occurred during the fourth coffee wave. The term “Waves of Coffee” refers to many epochs that represent the growth of coffee consumption. There are a total of 5 waves that may be characterized, each with unique characteristic features.

Fourth wave of coffee – Exploring the science / to analyze

The specialty coffee principles that had been established during the third wave were further investigated during the fourth wave of coffee. The production of coffee began to incorporate an increasing number of scientific ideas and procedures. In order to provide a result that is as consistent as possible, values are weighed, measured, and evaluated as part of the more precise and exact coffee brewing process.

The purpose of this time is to comprehend and develop the fundamental qualities that the coffee-making process requires. Beyond only coffee, this also includes the qualities and peculiarities of the chemical make-up of the water.


Why do we think that? We are still largely riding this wave. In the realm of coffee, there is still so much to learn and so much more for us to learn. The process of growing, plucking, removing the pulp, drying, roasting, cupping, brewing, and so on for coffee is intriguing and has countless variations. There is still a great deal to learn.



If there isn’t a layer of golden-brown froth on top, the espresso isn’t really an espresso. But did you know that this layer of foam has a name? specially crema. We’ll fill you in on everything.

The history of crema

Italians are the original source of the word crema. The inventor of the espresso machine known as “Achille Gaggia” created it with a much higher pressure than other models. On top, this produces an odd foam. He advertised his equipment with the promise of a “Natural cream coffee” in order to transform this into a plus. That Italian term eventually developed into an English term to describe the foam on an espresso.


The foamy layer that covers your espresso is referred to as crema. It not only looks delicious, but it also conveys a message about the espresso that is in front of you. If the coffee is good quality, you can tell from the foam layer. The hue and layer thickness are things you can examine. How long the foam layer is visible also matters.

During the roasting process, crema is already being created. CO2 is produced when coffee beans are roasted. When you crush freshly roasted coffee beans, the CO2 will still be present. When you brew the coffee, the extra CO2 will dissolve in the coffee, releasing the pressure. It resembles a soft drink in certain ways. The layer of foam had already developed at that point. Compared to soft drinks, the layer in espresso is considerably finer, but the idea is the same.

The quality of your espresso

But what specific information can you glean from these points? A quick-dissolving thin layer of crema is not a good indicator. It can be because the coffee is stale or the beans were ground too finely. Additionally, a light-colored crema is not a good sign. Your espresso most likely has a delicate flavor. This is frequently the cause of too little coffee or too cold water. The water was probably too hot if the layer was too black. The finely ground beans can possibly be at blame. This is also not good.

washed method

Coffee cupping

The flavors of two different coffee bean varieties might vary like day and night. Everybody has distinct tastes and interests. Coffee cupping is a common method of evaluating coffee beans. Read everything there is on this subject.

The phrase “cupping” may undoubtedly seem familiar to you if you enjoy coffee roasting. The ideal method for evaluating freshly roasted coffee.

Coffee cupping

The key prerequisite for a successful cupping session may be a consistent approach. Each coffee will have an equal chance as a result. It’s important to be well-prepared. When you’ve resolved this, you can begin the cupping session. Take note of the coffee’s aroma first. Then, fill each cup with boiling water. Give this some time. Next, it’s time for the final 10 evaluation points. If the cupping was successful, everyone has a distinct opinion on every type of coffee at the end of the session.

The 11 assessment criteria

There are eleven assessment criteria in a whole session. The smell comes first, followed by aroma, taste, aftertaste, acidity, body, balance, sweetness, clean up, uniformity, defection, and the overall rating, which takes into account all the factors. It is crucial that each participant evaluates these requirements.



Hopefully you don’t know what scorching implies, although many roasters may eventually encounter it. We will fill you in on every detail regarding this problem.

When roasting coffee, a few things could go wrong. These include one burning item. This flaw is visible to the naked eye, and if you make coffee with them, you will undoubtedly taste it. We’ll explain exactly what this means and how you may avoid it.

The meaning of scorching 

The majority of the time, scorching is caused by an overheated drum. The beans come into contact with a surface that is too hot. Lowering the coffee roaster’s charge temperature will stop this. The drum’s pace being too slow can also be a problem. The drum can be accelerated as another option.

How to recognize a scorch bean 

It is not difficult to identify burning. The roasted coffee bean has one side that is scorched and appears darker than the other sides. The flat side burns the majority of the time. You can taste something even though you can’t see it. The coffee has a burned, acrid, and smoky flavor. Not what you want in your coffee, unfortunately.

the details of coffee roaster

Charge temperature

Knowing the key terminology will make roasting simpler. Do you understand what we mean, for instance, when we mention the charge temperature? Let’s get started!

Various circumstances 

Your coffee roaster’s temperature changes depending on a number of factors. For instance, did you just start burning or have you been doing so all day? And is that day cool or hot? All of these situations may have an impact on the steps taken to achieve the ideal charging temperature. Your roaster needs to heat up far more slowly on occasion than other occasions. There is no doubt about it: you must treat this seriously because, in the end, it influences the bean flavor.

What does the charge temperature mean? 

One of the first issues you encounter when roasting is the charge temperature. It is, to put it simply, the temperature of the drum shortly before adding the beans. Although it may not seem crucial, this is actually quite significant. The entire roast can be impacted if your charging temperature is off. For instance, when the temperature is too low, the beans’ ability to develop taste is hampered. Even baked coffee can result from it. The beans may burn on the outside if the temperature is too high. something that neither you nor I want.

Best temperature 

The significance of the charge temperature has been sufficiently discussed. We’re sorry to disappoint you if you’re asking what the exact and ideal temperature is. Several factors determine the precise temperature. For instance, the size of your roaster and the type of roast you choose to use. There is no clear right or wrong in this situation.

roast finished
roast finished

First crack

When roasting, sound is an excellent indicator. Roasters listen for two temperature thresholds known as “cracks.” We’ll let you know about the first and second cracks.


One of the most crucial factors in roasting is the roast temperature and roast duration. There is a danger that the beans can burn if your roaster has an excessively high temperature. You won’t obtain the desired outcome if it is too low either. There are two temperature thresholds known as “cracks” that roasters watch for when discussing time.

The meaning of first crack

Approximately 196 °C (385 °F) will cause the coffee to start cracking. The start of a lighter roast is what we call the “first crack” at this point. The first crack occurs when a significant portion of the moisture in the coffee has evaporated, causing the beans to enlarge. When you are reproducing a specific profile, the first crack is an excellent indicator.

Second crack

A second one, logically referred to as the “second crack,” will come after the first one and a little more roasting time. The roaster’s inside is currently 224 °C hot. After a light, average, or dark roast is finished, this second noise will be heard. The majority of roasters favor these beans, but you have the option to keep roasting and wait for the second batch to yield an Italian or French roast. The bean’s structure is now starting to disintegrate. The oils that will surface lead them to darken and appear shinier.


Drying phase

There are numerous stages of coffee roasting, which we distinguish. The period of drying is one of them. We lay out the entire process for you.

Drying phase

The green beans must be dried before we begin the real roasting process because they have a relative humidity of 10%. Drum roasters are used in all PRECISION roasters. As a result, it takes the beans 6 to 8 minutes to finish drying.

The temperature of the beans

Since you don’t want to burn the beans throughout the drying process, controlling the roaster’s temperature is crucial at this point. The temperature of the beans will be close to 160 °C as this step transitions into the following.

Coffee roasting phases

In the image below, you can see how we distinguish between different roasting steps. You probably recognize that everything begins with green beans and concludes with dark brown beans. It stands to reason that the drying portion of the coffee roasting process comes first.

If you want to learn more information, please feel free to contact us.

20kg coffee roaster with PLC control panel and air feeding system
20kg coffee roaster with PLC control panel and air feeding system

Coffee terms: Stale coffee

Have you ever heard of old coffee? It might be mistaken for stale coffee. But aged coffee differs from stale coffee in that it can really be extremely good for the taste.

Stale coffee

The chemical process known as oxidation is the reason why coffee goes bad. Stale coffee can be compared to iron which has been exposed to oxygen for too long and has become rusty. The same thing occurs when coffee starts to taste stale. Due to excessive air exposure, the flavor of the roasted beans changes. Of course, there are other environmental factors besides oxygen that might affect the flavor of coffee. Heat or wetness are two examples.

Fresh coffee

The external factors that can impact the flavor of the coffee are one of the reasons why roasters vacuum-seal their beans. Using whole beans rather than beans that have already been crushed up can help maintain the freshness and flavor of the beans. Coffee staleness is accelerated by ground beans, which should be brewed as soon as feasible.

Taste of stale coffee

Stale coffee tastes exactly like coffee, while good coffee has a distinct flavor all its own. The sweetness, fruity undertones, chocolate flavor, and other flavors may all be tasted in good coffee, though. The flavor and aroma of coffee that is properly packaged and has not yet been ground is retained better.

mandheling coffee beans
mandheling coffee beans
high quality coffee roaster

Green bean management

The management of your green coffee beans, also known as “green bean management,” is crucial to the preservation and continued quality of your unroasted coffee. There are a few fundamental steps that you may take in your roastery to complete this as carefully as possible.

The measures will, of course, differ from roastery to roastery. A retail roastery, for instance, will manage and store its coffee in a different way than a medium- to large-scale semi-industrial roastery. When in doubt, speak with a coffee expert to develop a strategy that works for you.

Basic measures:

1 – Watch out for storing your green coffee too close to your roaster. You’ll realize that the unroasted coffee beans will be affected by the heat from the coffee roaster. Make sure the green coffee is kept in a location where the temperature of your coffee roaster won’t have a direct impact on it.

2 – Make sure the storage temperature is stable. Your green coffee will not be preserved if the temperature changes. As a result, be certain that the temperature in your storage space is always between 10 and 18 degrees Celsius.

3 – Assure a low level of humidity. An ideal humidity range for preserving beans is between 30 and 60 percent.

4 – The unroasted coffee beans should never be exposed to direct sunlight. You’ll see how this encourages your coffee’s degeneration. Place the green coffee ideally in complete darkness.

5 – Make sure there is adequate air circulation; ideally, the air should be recirculated four times an hour. This will keep the coffee fresher longer and prevent it from going bad.

best 12kg coffee roaster machine
best 12kg coffee roaster machine

high quality coffee roaster

Roasting terms: Second crack

The process of roasting coffee is intricate and filled with chemical interactions. These are carried out to enhance the bean’s flavors and smells. The second crack is one of the most crucial phases of roasting. When the coffee bean achieves a specific temperature and pressure, this happens. Anyone interested in making high-quality coffee must comprehend this and how it affects the final result.

The coffee bean begins to break when it reaches a temperature of about 385°F to 395°F. The first crack gets its name from this point on, when the bean starts to expand and leak moisture. The bean also experiences a number of chemical alterations during the first crack, including the emergence of its distinctive flavor and perfume.

Around 435–450°F, the second fracture starts to form at a higher temperature. At this point, the bean’s cell walls begin disintegrating, releasing stored gases and oils. The bean will also expand more than during the initial crack as a result, producing a louder popping sound. The roaster decides to halt the roast at the second crack since the roast has reached the required profile.

The body and acidity of the coffee are two of the most crucial effects. The acidity of the bean reduces as it heats up, and the brightness and fruitiness of the coffee start to fade. It is for this reason that lighter roasts, which are usually terminated before the second crack, have a stronger acidity and a more vibrant flavor profile. Darker roasts offer a lower acidity and a more potent, full-bodied flavor since they are often stopped during or after the second crack.

Any questions or would you like to find out more about roasting and coffee? Please feel free to contact us.