Coffee, it is taken for granted so easily, all you have to do is go to your local coffee shop ask for your favorite espresso based drink and a few minutes later you have a steaming cup of happiness! However you like your cup, there are a few people who know that from harvesting the coffee berries to you holding the hot beverage in your hand takes over 2000 hours or labor, processing, transporting, packaging, unpacking, roasting grinding and finally drinking.
It will take a thousand lifetimes to optimize all of the processes mentioned above, but roasting is the part I believe is the one that can be made a lot more efficient and environmentally friendly. Lots of research has been done on the taste chemistry of coffee, but what about the smoke coming out at the exhaust?
Why would anyone care about it? Firstly, as always, we have one planet and we need to protect it, or at least try our best. Secondly, energy costs money, an a roaster is a energy consuming monster because it works by means of heat, and finally the roaster starts working less and less properly every time you but a batch through your meticulously engineered coffee roaster, because condensables basically clog up the piping, causing the heating and cooling process to make the roast profile you use to love taste a bit different every time. So, doing this research will benefit the environment, the roaster/producer and the consumer.
In a typical batch roaster you will see the following curve:
The first drop in temperature is actually the beans just cooling the drums ambient temperature by taking out energy from the drum. When the beans then reach the critical temperature where the exothermic reactions inside the beans start to take place, this happens at about 85°C, from here on out the temperature keeps on rising to 200°C-220°C where the roaster will open the roaster drum and release the beans for cooling. During the roasting process there are two major events in the roasting process that takes place, the first and second crack, second crack is not always reached as you can see in the graph above the roaster made a lighter roast. The first crack is actually gas expanding and popping the bean open. Its like blowing a bubble to the point where it cant keep the pressure any more and then, BOOM! but a lot of small BOOMS.
What can can you make of these BOOMS? Well that there are gasses involved in the system, and these gasses are what needs to be quantified.
What is typically in gas from coffee roasters, and how much of it, relative to each other? The graph below will clarify it a bit:
All of the information above is just from literature I have done beforehand, but I started doing my own tests recently and I am so excited, I couldn't wait to share it with the rest of the world. Basically my project is to analyse smoke and tar coming from the typical roasting process of a batch coffee roaster. In this post not a lot will be said about the smoke, mainly because I have not done much work on it. But I have done preliminary to determine if there is any non-negligible amount of tar coming of the roasting of coffee. My logic told me that I will get absolutely no results with the small amounts of coffee I'll be using in the tests, boy was I wrong, and that made me super excited!!
So what is this test?
Using a Fisher tar assay, which is basically an oven with a pan or pans inside which can hold any sample, usually used for combustion of coal. The oven is then preheated to simulate a coffee roaster, then carefully the 50g of green coffee beans are inserted into the pan see the picture below to maybe get a better idea of how the rig looks like:
The combusted gasses, water and condensables are then channeled to a very crude condensation setup, which is lucky almost done being upgraded:
And what does this experiment yield?
Keeping in mind that only 50g of coffee was used, the following wonderful mess was made inside of the ball flask:
And the beans expanded as expected, approximately doubling in size:
Unfortunately, no conclusive results were found, except for the fact that vast amounts of tar is produced in the process of roasting green coffee beans.
I'm publishing this article with very little detail, mainly because I would love to get a response asap, and just to show how and what I am busy doing. So any comments or questions will be great!!
It will take a thousand lifetimes to optimize all of the processes mentioned above, but roasting is the part I believe is the one that can be made a lot more efficient and environmentally friendly. Lots of research has been done on the taste chemistry of coffee, but what about the smoke coming out at the exhaust?
Why would anyone care about it? Firstly, as always, we have one planet and we need to protect it, or at least try our best. Secondly, energy costs money, an a roaster is a energy consuming monster because it works by means of heat, and finally the roaster starts working less and less properly every time you but a batch through your meticulously engineered coffee roaster, because condensables basically clog up the piping, causing the heating and cooling process to make the roast profile you use to love taste a bit different every time. So, doing this research will benefit the environment, the roaster/producer and the consumer.
In a typical batch roaster you will see the following curve:
 |
| Temperature vs Time curve for roasting green coffee beans |
What can can you make of these BOOMS? Well that there are gasses involved in the system, and these gasses are what needs to be quantified.
What is typically in gas from coffee roasters, and how much of it, relative to each other? The graph below will clarify it a bit:
 |
| Cumulative mass loss and vapor products emitted from beans due dry matter breakdown versus total cumulative mass of all such products is (P-S) |
All of the information above is just from literature I have done beforehand, but I started doing my own tests recently and I am so excited, I couldn't wait to share it with the rest of the world. Basically my project is to analyse smoke and tar coming from the typical roasting process of a batch coffee roaster. In this post not a lot will be said about the smoke, mainly because I have not done much work on it. But I have done preliminary to determine if there is any non-negligible amount of tar coming of the roasting of coffee. My logic told me that I will get absolutely no results with the small amounts of coffee I'll be using in the tests, boy was I wrong, and that made me super excited!!
So what is this test?
Using a Fisher tar assay, which is basically an oven with a pan or pans inside which can hold any sample, usually used for combustion of coal. The oven is then preheated to simulate a coffee roaster, then carefully the 50g of green coffee beans are inserted into the pan see the picture below to maybe get a better idea of how the rig looks like:
 |
| Fisher tar assay: oven, pan and thermostat |
The combusted gasses, water and condensables are then channeled to a very crude condensation setup, which is lucky almost done being upgraded:
 |
| Condensation setup: ball flask in ice water |
And what does this experiment yield?
Keeping in mind that only 50g of coffee was used, the following wonderful mess was made inside of the ball flask:
 |
| Tar produced from 50g of coffee being roasted |
 |
| Roasted beans vs green beans |
I'm publishing this article with very little detail, mainly because I would love to get a response asap, and just to show how and what I am busy doing. So any comments or questions will be great!!
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