What is the reason why there is no hamburger for hand-made coffee? What if the steamed coffee powder does not expand?

introduction

When brewing coffee, when the hot water comes into contact with the dried coffee powder, it will bulge a big "burger", which is very healing. But sometimes coffee doesn't form a hamburger after the water is poured. How is that possible?

Reason 1: Coffee beans are not fresh

In the first stage of steaming, coffee expands because the beans contain carbon dioxide gas after roasting, which expands and releases carbon dioxide gas when exposed to water. But coffee beans continue to emit gas after roasting, and when the gas is almost exhausted, it will not expand into a hamburger when it encounters water. The amount of gas in coffee can also show the freshness of coffee beans. So Front Street Coffee judges whether a coffee bean is fresh or not based on how much it swells during steaming.

As for why the taste of fresh coffee beans is about 1 month. Because most coffee beans end up emitting carbon dioxide in about 30 days. But this is not absolute, some coffee beans will take longer to exhaust (also related to the storage method). Therefore, it is a scientific method to confirm whether coffee is fresh by the degree of expansion of its burger during steaming.

Reason 2: Coffee ground too coarse

The thickness of coffee powder will also affect the expansion state of coffee, when the coffee is ground coarsely, the coffee particles will be large, then the time required to saturate the water absorption will be longer, then the exhaust effect will be poor, so the degree of expansion will be smaller, and there will also be "Hamburg" center collapse phenomenon. The reason for this is that coffee powder is too coarse and steamed too long.

Even if the grind exceeds the coarseness of the grind range for hand-brewed coffee, water flows into the lower pot due to the influence of gravity without being fully extracted. Then there will be no expansion.

Therefore, it is very important to choose the correct grinding degree. The grinding calibration of Qianjie coffee is calibrated by using a sieve with an aperture of 0.85mm. The fineness of hand-brewed coffee is selected at a grinding degree of 80% through the sieve.

Reason 3: The water temperature is too low

Water is the main medium for extracting coffee, the higher the water temperature, the more active the water molecules, the higher the efficiency of water penetration into coffee powder; the same, the lower the water temperature, the more stable the water molecules, then the efficiency of penetration into coffee powder is lower. Therefore, when the low water temperature is stewed, the gas in the coffee powder is slowly discharged, and it is difficult to form a coffee "burger". Through experiments, Qianjie concluded that in the case of stable other parameters, the water temperature above 80 ° C can form a coffee "burger". However, it is generally recommended to use 86-93℃ before brewing.

Reason 4: Shallow baking degree

The deeper the coffee roasting, the looser the internal fiber structure, the better the water absorption and exhaust. On the other hand, the shallower the coffee roast, the more complete and dense its structure, the worse its water absorption and exhaust performance. So some very lightly roasted coffee in its fresh state doesn't have much of a "burger."