Hand made coffee tips| What is pressure swing extraction? Is there pressure swing extraction in hand flushing?

Professional coffee knowledge exchange more coffee bean information please follow the coffee workshop (Wechat official account cafe_style)

When it comes to pressure swing extraction, the first thing we will think of is the pressure swing extraction function of the high-end Italian coffee machine. For example, the pressure swing extraction of a coffee machine is as follows: pre-immersion pressure 2bar, front-stage extraction 5bar, middle-stage 9bar, back-segment 5bar. The advantage of this pressure change is that the low-pressure water supply makes the coffee muggy exhaust easy to extract during pre-soaking, and the medium pressure in the front section is just right to extract the sweet and sour taste and small molecular flavor, while the larger molecular nut and caramelized flavor in the middle section needs more pressure extraction. the reduction of pressure extraction in the back stage makes the coffee not easy to extract, but also can extract distillation flavor and sweetness at the same time.

Then we had a thought: can this mode of pressure swing extraction be used in hand extraction to make coffee taste better?

Where does the pressure come from?

The pressure of the coffee machine is provided by pump and boiler pressure, and the pressure source of hand flushing is the impact of water flow. At present, most manual flushing uses V60 series filter cups, so let's start from here today.

When brewing coffee with V60, there are two factors that can change the impact force, one is the size of the water flow, and the other is the height of the water column, and of course our water flow can not be too large, so change the height of the water column to achieve this hand pressure extraction.

Watch the video for 3 minutes. Please watch it patiently.

The coffee used in the video is Yega Xuefei sun berry orchard, the amount of powder is 16 grams, the water temperature is 90 ℃, because the hand rack is used, the powder-to-liquid ratio is 1:15. When steaming, we inject water with small flow and low water level to wet coffee powder quickly and uniformly; the first part of the extraction is injected at a height of 5: 6 cm from the powder bed, and the height of the high water column increases with the rise of the water level; in the middle of the extraction, slightly increase the flow and pull up the height of the water column to reach the maximum extraction pressure, so that the coffee powder rolls up to extract the main flavor of the coffee, and the pause in the middle is to prevent the water level from rising too high to hinder the scouring strength of the water. Then continue to extract with maximum impact force, and gradually reduce the height of the water column to reduce the impact extraction to avoid over-extraction, and remove the pot before the coffee liquid falls completely.

In this way, the fruit aroma of the raspberry orchard is rich, the acidity and sweetness are good, the taste is round, the finish is long and has no exquisite dryness.

We also used more than a dozen other types of coffee to brew in basically the same way (the water temperature and grinding degree are fine-tuned), and found that this technique is generally suitable for floral and fruity flavor coffee, while deep-roasted taste coffee is not suitable for high-impact extraction.

In addition, when brewing coffee rich in flavor substances such as rose summer, the extraction rate can be relatively high, so you can keep the water column high until the end, and the ratio of powder to liquid reaches 1:16 or even 1:17, which can open the flavor layer. let the taste richer ~ because the extraction rate is improved, the taste will not be light!

Of course, the above techniques are only a "framework", for different coffee in changing the impact of the water will be different, and we can also according to our previously published article: in-depth exploration, how to achieve the desired coffee flavor? To change the timing of pressure extraction.