I’ll be honest…I love coffee…as long as it’s good. After all, there are many options out there and some are less appealing than others…

bulletproof(I prefer cream, thanks)

One of the characteristics behind the perfect cup is the origin of the bean. There are so many different types of coffee beans and everyone has their favorite. At one time, I was all about the Blue Mountain coffee. Then I went through an African phase. These days, I’m loving…

poasThe Volcanic Earth!

But source is really a personal decision. The science comes in when it’s time to turn those beans into that delicious black elixir.

The most known step is the brewing process. Add hot water to beans…wait…pour. Simple enough, right? But it’s a little more complicated than that…

oh-really(He was such a great actor…)

If the water is too hot, the taste will be bitter. If the water isn’t hot enough, the extraction will be incomplete. The best temperature is somewhere between 90 and 95 degrees Celsius (or about 195-205 degrees Fahrenheit). The perfect way to accomplish this is by using…

kettleA transparent kettle!

Not only can you monitor the boiling process, it’s also really fun to watch the as the water increases in temperature. The way the various molecules move around and create some visually stunning waves is captivating. Then there’s the actual boiling moment when the seemingly serene turns into churning chaos. It’s absolutely fascinating…or depending on your perspective…

yawn(I’ll get on with it)

Going back a step, the nature of the beans is also important to the prefect brew. A uniform distribution of same sized particles is needed for maximal extraction of those flavourful chemicals.

To achieve this, we use grinders. I know they come in different shapes and sizes but they all have the same parts…the hopper, the motor, the shoot and the actual grinding burs….

(It’s a relatively simple design)

You put the beans in the hopper, turn on the power and let the burrs do their job. Out the shoot comes the ground coffee and you’re good to go.

If, however, you take a microscope to those particles and examine the size of the the grinds, you’ll see a distribution curve of sizes ranging from about 1/100th of a millimetre to 1/10th of a millimetre. Graphically, it looks something like these graphs…

bean-image-2

(The higher the hump the more particles you’ll find)

This distribution curve is fairly common among all grinders. The majority will fall into one of a few particle sizes with the rest being spread out evenly across the spectrum. The goal is to be maximize the number of smaller particles to increase surface area….

makes-sense(At least I hope it does…)

There is, however, a slight twist. When grinding happens on a regular basis – such as in a coffee shop – another physical parameter enters the equation….

heat(Temperature)

As the blades get hotter, the possibility for a different grind may occur. This could lead to a change in particle size and alter the distribution. But no one really knows how exactly heat may effect the perfect cup.

For a group of researchers – and I am sure coffee lovers – this question needed to be answered. They underwent an series of experiments involving temperature and grinding and found a rather interesting phenomenon. As the heat increased, so did the size of the particles. In addition, the evenness of the distribution…

bean-image
(Colder temperatures mean smaller particles)

The study reveals two important recommendations to achieve the perfect cup. First, the beans should be kept cold prior to grinding. Although the experiments spanned from room temperature to liquid nitrogen, the most practical option would be to put the coffee…

beans-freezer
(Coffee on ice…not iced coffee)

The best option is to take as many beans as you need for a week and put them in the freezer. This will ensure the the majority of particles will be small enough to maximize surface area and provide the most flavour. Limiting the number of beans used will also prevent that freezer burn taste over time.

The second applies to coffee shops who are continually grinding beans. Based on the experiments, as the grinder gets warmer, the size of the particles increases. To achieve consistent results, the grind setting may need to be reduced over time or the burrs need to be kept cool at all times. Although the authors didn’t discuss how this could be achieved, there is one way that might work…

ice-barIce baristas!

The final point was more in passing as the researchers tested several different types of coffees from across the world. No matter where they were sourced, the beans all acted in a similar manner. So, regardless if you are a lover of Ethiopian Yirgacheffe, Indonesian Sumatra, Brazilian Minas, or like me, Costa Rican Paos, keep those beans cold and you’ll always enjoy that perfect cup of coffee.

If you want to read the entire study, you can find it here:
The effect of bean origin and temperature on grinding roasted coffee

 

 

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