When initially learning how to brew coffee, one of the first things most people notice is the sheer number of factors that might influence the final product’s quality. This essay will describe what many people consider to be the most crucial variable; if you can master this, you will be able to create coffee that is superior to that served at most cafés.
The following are some of the factors that might have an effect on your coffee:
- The quality of the beans
- The roast and blend
- The machinery (maintained machine, and grinder)
- The temperature of the machines heads at the time of extraction
- The coarseness of the grind
- The extraction cut off point
I’m going to stop there, but as you can see, there are at least that many more before I even start talking about the barista technique or the milk, and the list is virtually never going to finish.
The grind coarseness
It should be the coarseness of the grind alone that determines how quickly or slowly the coffee is extracted through the handle (tamp pressure is always the same). The flavours that may be found in ground coffee vary from those that are sweet and fragrant to those that are quite bitter.
Even a little change in the grind may have a significant effect on the extraction rate, which in turn determines which flavours you get to savour and which ones you have to suffer through.
The grind coarseness, which is controlled by the extraction rate, is the primary factor in determining the flavours that are ultimately delivered to the cup.
- If it extracts too quickly (because the grind is too coarse), there is not enough time for the hot, pressurised water to extract the sweet, desired flavours, and as a result, you will be left with a coffee that is watery and has a bad taste.
- If it extracts too slowly (if the grind is too fine), the hot, pressurised water will take so long to get through the grinds that it will end up burning the coffee on the way through, leaving the drinker with a bitter taste in their mouth that will last for up to an hour. If it extracts too quickly (if the grind is not fine enough), the water will get through the grinds quickly enough.
The precise ideal extraction rate will vary somewhat from blend to blend; nevertheless, it should never be rushing out of the spouts, nor should it be merely drip, drip, dripping during the whole extraction process. Rather, it should be a steady stream of liquid that is extracted at a steady pace (a bit at the start is fine). From one spout, the extraction comes back in towards the centre of the handle, giving the appearance of the curve in a rat’s tail. This is the perfect extraction, and it may be characterised as a “rat’s tail.” If you use freshly roasted beans and do the extraction process correctly, you will end up with a coffee that is naturally sweet, has a rusty brown colour, and that you would be willing to spend twice as much for.
So go ahead and experiment by switching the setting on your grinder back and forth between the fine and coarse positions. Depending on the kind of grinder, even a little change might have a significant impact on the flow of the extraction.
It is my hope that by emphasising how important it is to get the grind exactly right, your coffee grinder won’t be one of the many that I often come across that has a notice that reads “do NOT change the grind,” since doing so really ought to be required. Enjoy…