For fresh coffee beans, when purchasing, pay attention to whether the color of the beans and the size of the particles are consistent. Good coffee beans have a bright and shiny appearance and have a strong aroma without mixing with a peculiar smell. Regardless of the type of coffee bean, freshness is an important factor affecting quality. When buying, grab one or two coffee beans and chew them in your mouth. It should be crisp and sound (indicating that the coffee is not damp), and the fragrance should be left on the cheeks. Buy coffee with a crisp crust. If the coffee beans have lost their aroma or smell stale, it means that the coffee beans are no longer fresh and are not suitable for purchase.
Freshly roasted coffee beans are not suitable for immediate consumption and should be stored for a week to fully release the gas in the beans.
The great thing about coffee is the aroma; that aroma starts to lose the moment the roast is done. No matter how expensive coffee beans are, if they are not fresh, the taste will be greatly reduced. In his book Espresso coffee: the science of quality, Andrea Illy, the current helm of the old Italian coffee brand, illy, has an article detailing the effect of coffee beans “off-flavor” and different packaging methods on quality. Each kilogram of coffee beans, in an unsaturated environment, emits about 6 to 10 liters of carbon dioxide, which is equivalent to 1% to 1.2% of the total weight of the beans. 35% of them are discharged in the first 3 days after baking. And with the carbon dioxide emission, there is also the same amount of volatile aromatics. That is to say, some flavors will dissipate after the coffee beans are roasted for the first 3 days without drinking. The author further mentioned that stale beans not only lost with good taste but also create a bad taste. The compounds in the beans are affected by oxidation and the taste can become negative. Therefore, the coffee on the supermarket shelves is generally slightly oily. Because it usually takes several months from foreign baking, importing to the shelves. The “Tasting Period” (Note: not the expiration date) has long passed.
Generally speaking, the best drinking period of coffee is one week after roasting, when the coffee beans are the freshest and the aroma Aroma tastes the best.
In addition, the purity of coffee beans is also another factor to consider. Experts choose coffee, not necessarily by the size of the particles, but by grabbing a handful of regional coffee beans, about dozens of them, take a look at each one. Whether the color of a single bean is the same, and whether the particle size and shape are similar, so as not to buy inferior products disguised as mixed beans. But if it is a blended coffee, it is normal for the size and color to be different. In addition, heavy fire and medium-deep roasting methods will cause the coffee beans to produce oil, but if the beans roasted more lightly are oily, it means that they have deteriorated, not only the aroma and mellowness will be reduced, but also astringency and sourness will appear. In short, when purchasing coffee, you should pay attention to its freshness, aroma and stale taste, and the ideal purchase quantity can be consumed in half a month.