Although it may not seem like it, coffee is a fruit that spoils over time. As with peeling and cutting an apple that becomes brown after a few minutes, the small particles of ground coffee come into contact with oxygen and quickly lose their aromas and flavour.
On the contrary, coffee beans better maintain their properties and freshness because they delay their oxidation considerably.
Therefore, try to buy the amount of coffee you are going to consume after a month from its roasting date. For example, a 250-gram coffee bag usually lasts up to 2 weeks. When I go to buy coffee to grind at home, I choose one toasted in the last two weeks.
The carbon dioxide (CO2) also plays a role in the oxidation process of coffee because it slows down. The CO2 accumulates inside the coffee bean during its roasting and is released little by little at the end of this. Once the coffee has been ground, the CO2 disappears in a few minutes, accelerating its oxidation.
Coffee also contains beneficial antioxidants for health such as caffeic acid and melanoidin. Both originate at high temperatures during coffee roasting and, as with CO2, these compounds become rancid when they come into contact with oxygen, especially if the coffee has been ground.
That said; try to keep the coffee beans for as long as possible. No matter what you paid for your coffee: if it has been previously ground, you will not take full advantage of it. It is enough with a decent coffee and a low-end manual grinder to leave with an advantage over any pre-ground coffee.
Conical vs flat wheels
Depending on the mechanism you use to grind coffee beans, the grinders can be conical or flat. In general, flat wheels have a more affordable price than conical ones. Both options are suitable for uniform grinding.
Finally, depending on the material used in the manufacture of the wheels, the grinder wheels can be made of stainless steel or ceramic. Both materials ensure that the grinder is not overheated during use.
How to adjust the coffee grinder
As we have already mentioned, each coffee maker requires a different grind. Try using a fine grind in a French press, and you’ll see what I’m talking about. To achieve this, the grinders have two methods that allow us to choose the thickness of the grind: the method with scales and the manual.
Grinders with scales have a predefined grinder selector to choose the one that best suits our coffee maker. There are grinders with 5, 12, 20 or more than 50 levels of grinding that normally range from a thinner thickness to a thicker one.
Manual grinders allow you to choose the degree of grinding by precisely adjusting the distance between the grinding wheels that grind the coffee. By not having grinding options, you will have greater freedom to choose the thickness of the grind and experiment with your coffees. However, you will need a higher mastery of the grinder and the preparation method you use.
Tricks to grind coffee at home
- Never buy roasted coffee: use 100% Arabic fresh coffee to taste all its aromas and flavour.
- Grind the coffee just before preparing it to prevent oxidation.
- If the coffee has gone under-extracted and has a sour aftertaste, try grinding the beans finer. By grinding them too thick, the coffee infusion has not extracted all the coffee flavour, that is, the ground coffee has not been sufficiently moistened.
If, on the contrary, the coffee has a bitter aftertaste (over-extraction), you will have to grind thicker. In this case, the coffee particles have been soaked longer than they should.