Walking into the kitchen in the morning and pressing the button on your De'Longhi coffee machine, many people run into the same small puzzlement: it is clearly the same machine, yet sometimes the espresso comes out thin as water, and sometimes it is so burnt, bitter and astringent it is hard to swallow. In fact, the key to making a balanced, smooth cup of good coffee at home lies in understanding the little quirks of that pair: extraction yield and concentration.

We can think of coffee as a bowl of soup: concentration tells you how salty the soup is, while extraction yield tells you how much of the ingredients' flavor has been cooked out. If the coffee tastes light and flavorless, it usually means too few solid flavor compounds were brought out; if the back of your tongue feels dry and there is an unpleasant burnt, bitter, astringent taste, that is usually over-extraction, which has also washed out the undesirable off-flavors of the woody fiber.

To pull espresso back into the smooth range, fine-tuning the parameters is actually very simple. For daily extraction, you can load a double basket with 18 g to 19 g of coffee grounds, extract 36 g to 38 g of espresso liquid, and keep the extraction time at 25 seconds to 28 seconds. If the flow is like an open floodgate and the taste is on the sour, thin side, adjust the grind one step finer; if the flow is too slow, intermittent and astringent, adjust it one step coarser.

Besides the grind setting, water temperature is also a great helper for adjusting extraction yield. De'Longhi machines usually offer high and low temperature settings, and the hotter the water, the more actively it dissolves flavor. Dark-roasted beans are rich in oils, so lowering the water temperature slightly can reduce the burnt, bitter sensation; if the beans are on the lighter-roasted side, raising the water temperature can fully release the fruity acidity and sweetness. Once you understand these patterns, you have a reliable guide for choosing beans.

If you prefer a rich, oily mouthfeel and like making large lattes, Qianjie Classic Blend is a worry-free partner. This bean uses the traditional Mamba blend formula, designed specifically for espresso and moka pots; even with a non-professional home machine it can press out an especially dense, thick crema, and it enters the mouth mellow and smooth. Whether you add milk for a cappuccino or make a dirty coffee, it is full of aroma.

If you drink coffee very frequently and are after everyday value for money, take a look at Qianjie Black Cocoa Blend. It uses a carefully matched all-arabica bean selection, and although the price is friendly, its crema performance and richness are in no way inferior. One deep breath in is full of dark chocolate and nut aromas, and even if you pour the espresso into a large glass of iced milk, you can still taste a rich, solid base.

If you prefer the familiar, balanced classic café taste from memory, Qianjie Specialty Blend is a dependable choice. As an evergreen item in Qianjie stores for nearly ten years, it blends Brazil Cerrado and Colombia Huila just right: the slight bitterness of dark chocolate accompanied by nutty sweet aroma. Made into a hot latte the milky sweetness is pronounced, and made into a hot americano it is mellow and smooth on the throat; it is the type that stays pleasant to drink however you adjust it.

Of course, many friends do not like the too-strong, too-bitter dark-roast flavor, and instead prefer something light and refreshing. In that case, Qianjie Strawberry Candy coffee beans are very suitable. It relies on the native flavors of different origins interwoven into a distinct strawberry gummy candy sweetness. People who fear bitterness can extract a shot from it and top it with soda water for a specialty drink: the fruity aroma overflows and is lively, and the whole cup of coffee becomes light and bright.

Every coffee bean has its own character; some suit a rich, slowly savored cup, while others suit a light, relaxed one. As long as you master the grind size and the weight of the extracted liquid, and slowly feel out the state that suits your taste in the kitchen, even an ordinary De'Longhi machine can steadily serve up a fragrant, full-bodied cup of coffee, letting every ordinary morning be gently wrapped in thick coffee aroma.