Correct storage of coffee beans and purchase of high-quality coffee coffee roasted Italian mixed beans

By observing Crema, we can judge the freshness of coffee beans, the completeness of coffee extraction and the uniformity of coffee extraction.

How to tell if the coffee beans are fresh: although you can tell that the beans are fresh when you observe a lot of foam, there is also a possibility that Robusta is high. So we can observe the state of foam precipitation instead. If it is very fresh, the whole process of bean extraction will take the form of crema, and when these crema settle down, they will be clearly divided into two layers. If it is a long-term bean, you will see that there is not much concentrated foam coming out of the shunt nozzle during extraction, usually this cup is thin and watery, and the crema will soon dissipate.

How to judge whether the extraction is complete: the darker the color of crema, the more dissolved substances are extracted.

How to judge whether the extraction is uniform: if the crema is stable, the concentrated color is beautiful and the texture is thick, which means that the channels and depressions in the extraction process are less likely to occur.

Coffee spoils very quickly after roasting. Once the aroma is gone, the coffee is completely stale. Roasted coffee deteriorates much faster than fried tea. Oxygen, moist air and sunlight can cause the taste and aroma of coffee to disappear instantly, so the coffee grinder used in the coffee shop is sealed, and the barista should always make sure to cover the lid to prevent the coffee from spoiling. Fresh coffee tastes better, reflecting the natural sweetness of coffee beans. Ground coffee powder deteriorates faster, which is why we only grind a certain amount of coffee before making coffee, rather than grinding it all at once. You'd better use up all the coffee powder stored in the powder compartment within an hour, and the real quality pursuer will ask the barista to use up all the coffee powder within 2 minutes.

The ideal storage temperature of coffee is 7 ℃. Remember, never put coffee in the refrigerator, because too low temperature will make the inside of the coffee crystallize, thus absorbing the moisture inside the coffee and making the coffee taste bad. You'd better store your coffee in a cool, dry place and stay away from the sun. Never put coffee with other strong foods or chemicals. The best way is to store the coffee in a sealed plastic bag. If it is not sealed, the coffee will absorb all the flavor around it like a sponge.

When buying coffee, make sure it is in a sealed bag. The sealed bag must be equipped with an one-way vent to help coffee release carbon dioxide (coffee usually releases a certain amount of carbon dioxide after roasting). You also need to pay attention to the baking date on the bag. Coffee should not be stored for more than 6 weeks after roasting (some people think it is 3 weeks). The surface of old coffee beans will condense grease. If you don't smell the pungent aroma when you just open the bag, the bag of coffee beans is likely to have gone bad. The best way is not to buy too much coffee at a time, the amount you buy depends on your actual use.