Cup o'Joe-The surprising secrets of espresso скачать в хорошем качестве

Cup o'Joe-The surprising secrets of espresso

Baristas know how to make a great cup of espresso, right? After all, that is their business. Ask one and chances are that as he or she pushes buttons and turns dials on a machine that resembles the control panel of a jet fighter, you will be told that to maximize extraction of flavour, temperature is critical, should be around 92 degrees Celsius, water pressure should be 6-9 bar, the basket should be filled to the top and tamped with a pressure of 98 Newtons, and the coffee should be finely ground. Well, as it turns out, that isn’t exactly correct. At least about the grind and the basket being filled to the top. We know this because scientists have done extensive investigations of espresso making. The papers they produce are full of complex equations and graphs and look like they would be at home in a quantum mechanics journal. Intuitively, one would think that since smaller particles have a larger surface area, more of the coffee components, of which there are some 2000, would be extracted. Also, since there is less space between the smaller particles, water would be expected to flow through more slowly, and the longer contact time would lead to greater dissolution of flavourful compounds. Furthermore, the more coffee there is in the basket, the more coffee components are available for extraction. Experiments, however, show that this is not the case. If the coffee beans are ground too fine, there is less flavour extracted. There is a “Goldilocks” setting of optimal grind for extraction, not too fine and not too coarse. And as another surprise, if the amount of coffee is reduced by about 25% in the basket, the coffee is more flavourful. How can this totally counterintuitive effect be? The researchers have an answer. With too fine a ground, the water actually flows through more quickly because some parts of the coffee bed are packed more tightly and the water finds the easiest channels through which to pass. With a coarser grind, the water flows evenly through the whole bed of coffee because there is plenty of space between the grains to flow through. A similar argument is used for the total amount of coffee. When the basket is filled to the top, the flow is not homogeneous and the water tends to pass only through the middle of the basket. If there is space at the top, the water spreads over the whole surface and makes greater contact with the grains. Anyways, that is the argument. A further factor is that as more compounds are extracted from a single grain, the grain becomes more permeable to water. In other words, channels form within a grain that allow more water to enter and increase the extraction. I’m not sure that the world is a better place because we now know that there is an optimal grind setting for the most flavourful espresso. But coffee houses will appreciate that they can actually deliver a better cup of espresso by using less coffee. The espresso researchers estimate that given the US consumption of 124 million espresso-based beverages a day, $1.1 billion dollars will be saved per year. On the other hand, coffee producers will not appreciate that. As for me, I use the little espresso capsules. Not very environmentally friendly, but I don’t have to grind, don’t have to twist any dials and I get to enjoy a good cup of espresso.