The flow rate of coffee is abnormal. Why? What are the factors affecting the flow rate of coffee?

When I'm usually making coffee, I feel anxious watching the speed of the coffee liquid flowing down. But I don't know where to start. I think the degree of grinding is too fine. If it's thicker, it's still like this. Is there no way to save your cup of coffee? Don't worry. Today, the editor will talk to you about what factors will affect the flow rate of a cup of coffee.

| | filter cup & filter paper |

Yes, that's right, the filter cup is the most important factor affecting the flow rate. The difference in the flow rate of filter cups with different shapes leads to the final flavor of coffee.

The reason why the filter cup affects the flow rate is mainly due to the size of the filter hole under the filter cup and the distribution of the ribs on the top of the filter cup, such as fan-shaped and cake-shaped filter cups, the bottom of the filter cup is smaller and the flow rate is slower, while the conical filter cup, such as V60, has a larger diameter and a faster flow rate.

Even if it is a tapered filter cup, it will be different because of the difference in the distribution of ribs, just like the KONO filter cup. Because of its small caliber and short ribs, there is no exhaust space, so it is basically a state of immersion and extraction. There is also the ice pupil filter cup, the ribs are distributed vertically according to the ladder type, but the top is sealed, so if the water flow is too much at once, the water level is too high to flood the diversion channel, and there is no room for exhaust, the water level will drop slowly.

Do not think that filter paper is just a thin piece of paper used to separate dregs. When it comes to filter paper, most of them will consider whether it has been bleached or not, but this is not the only difference between filter papers. The quality of filter paper is also important for keeping coffee utensils clean and good filtration flow rate. the thickness of filter paper will affect the filtering speed of coffee.

The degree of fit between the filter paper of the filter cup will also affect the flow rate of the coffee liquor. if the filter paper will fit the lower hole, it may cause the flow rate to be too slow and lead to excessive extraction, and the coffee will have a bitter taste, so the editor suggests choosing a match rather than a full fit.

| Coffee beans

Perhaps this is easy to overlook, but it is true that the quality of coffee beans will affect the flow rate of coffee!

Combined with our long-term cooking experience, heavily fermented beans will have a different flow rate. For example, for Costa Rican heavily fermented honey-treated beans, compared with water-washed beans, even if the varieties and producing areas are the same, the elevation and baking degree are similar, but in the process of cooking, the flow rate can be obviously felt faster (when the parameters and techniques are the same). For example, the three musician series beans we bought last year: Bach, Mozart, Beethoven and the Costa Rican Pillon processing plant we recently discovered, beans with a strong sense of fermentation, even if they are lightly baked, but the flow rate is relatively fast.

| | degree of baking |

The texture of shallow baked beans is relatively tight, and most of them will be beans from high-altitude producing areas, and the texture will be much harder. Shallow baked beans exhaust is not exuberant, during the end of exhaust, easy to sink backlog filter, so it will lead to slower flow rate.

On the other hand, the deep-baked beans are relatively loose, with good water absorption and exuberant exhaust, the powder layer is easy to expand and bubble by water, and the coffee powder is easy to float on the surface, so the speed of water flow naturally becomes faster.

| Grinding thickness

The thickness of the grinding will also affect the flow rate of the coffee liquid, the editor thinks that we should have a very intuitive feeling!

The finer the grinding, the coffee powder is easy to accumulate on the filter paper, and the extraction resistance is greater, so the flow rate is slower and the extraction time is longer. The extraction rate of the substances contained in coffee is high, and the coffee brewed is strong.

The coarser the grinding, the larger the gap of the powder layer, the less coffee powder in contact with hot water, the weaker extraction resistance, the faster coffee dripping speed and the lower extraction rate, so the coffee flavor is lighter.

Sometimes when the bean grinder is not very good, there will be a lot of fine powders, which are all piled up at the bottom, blocking the filter paper, causing the water to flow, resulting in too many substances extracted from the coffee powder. Coffee tastes with obvious bitterness, miscellaneous taste and astringent taste, so you get a cup of over-extracted coffee.

| | current

During brewing, the size of the water flow and the speed of water injection will affect the flow rate of coffee.

We need a penetrating column of water when making hand-made coffee! The so-called penetrating water column is probably the state of being thick at the top and thin at the bottom, that is, the width of the water coming out of the spout should be wide, and the shape of the end of the tail section should be sharp.

If the water supply is too gentle and the penetration of the water column is not good, the water will be fed repeatedly in the same layer, which will only speed up the extraction on the surface of the first layer of particles, thus making the coffee liquid bitter.

The water column with good penetration can avoid the problem of repeated draught. After entering the interior, the water will spread rapidly from the inside to the outside, greatly reducing the condition of repeated draught and greatly improving the uniformity of coffee powder draught.

| | level of water level |

The water level in the filter cup will also have an impact on the flow rate, especially in the V60 filter cup, because the ribs are distributed in the whole filter cup, which leads to too much water supply, when the water level is high, the water will flow away directly from the edge of the filter cup.

When making hand-brewed coffee, there are still many factors that will affect the slower flow rate of coffee. Next time, if you encounter this kind of problem again, you might as well start from these aspects to see what will cause it.