Coffee grinder cone grinding knife plate and grinding knife plate, what is the difference in the flavor of brewed coffee?

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Yesterday, I talked about how to adjust the newly bought bean grinder. Today, we compared the ZD-10 of Huijia with the Forte-BG bean grinder we usually use. Further confirm the degree of grinding and correct the grinding.

Bean grinding machine can be generally divided into flat knife, cone knife and ghost teeth three categories.

Flat knife: coffee beans are ground into particles in a cutting way, so their shape is mainly flaky.

Cone knife: coffee beans are ground into particles by grinding, so its shape is mainly block.

Ghost teeth: coffee beans are ground into particles by grinding, so their shape is mainly closer to round.

Today, we compare the conical cutter disc with the flat cutter disc, and calibrate the grinding degree and brewing flavor of Huijia ZD-10 of conical cutter disc to the grinding degree and brewing flavor of Forte-BG bean grinder of flat cutter disc.

So let's first understand the difference between a flat knife and a tapered knife

[Flat Blade Millstone]

Advantages and disadvantages:

The flat cutter grinder consists of an upper cutter disc and a lower cutter disc, the base is fixed on the motor, and when the motor is started, the upper cutter disc and the lower cutter disc are rotated to generate cutting action.

As coffee particles fall from the center, the rotating blade at the bottom rotates the beans to the periphery, pushing them into the toothed blade section for grinding.

The upper and lower cutter plates of the flat knife are placed in parallel, so the coffee beans need to rely on the rotating force of the bottom cutter plate to push the coffee beans into the cutter plate, so the weight of the coffee beans placed above will affect the uniformity of the coffee beans entering the cutter plate, which in turn affects the uniformity of grinding; in addition, due to the pushing, the number of collisions between the coffee beans increases, resulting in an increase in the proportion of fine powder. This is the reason why the particle uniformity of the common flat knife grinder is slightly poor and the fine powder is more.

The coffee particles ground by the flat knife are flaky, and the flake can increase the cell wall area, so the coffee concentration and extraction rate can be improved in a short time with the flat knife, so that the coffee aroma can be significantly improved in a short time. At the same time, because of its flat shape and small volume, when the extraction time becomes longer, the xylem of the particles will absorb too much water, resulting in increased foreign taste and astringency.

[Cone Blade Millstone]

Advantages and disadvantages:

Cone knife grinder is placed at the bottom of the conical cutter disc, and then with the outer ring cutter disc to grind, coffee beans fall from above, coffee beans will be pulled down with the rotation of the conical cutter disc, and then produce grinding action, but also because of the relationship from top to bottom, so the particles can be pushed out without pushing coffee, compared with the flat knife grinder, the number of collisions between particles will be reduced a lot, so the proportion of fine powder produced by the cone knife will be reduced a lot compared with the flat knife, And the coffee grind uniformity will be greatly improved.

The particles ground by the cone knife will be close to the granular shape, resulting in a longer water absorption path of the coffee particles, and it takes a longer time to contact the water inside. Therefore, the soluble substances released by the cone knife particles in the early stage will be less, resulting in a concentration that is not too high in a short time. At the same time, because of the granular shape, even if extracted for a long time, the xylem absorbs less water, and it is less likely to produce miscellaneous taste and astringency.

We also know about the knife plate. The following small series selected the flower from Sidamo. For the flat knife and taper knife, we conducted cup test and brewing test.

Hua Kui

Raw Bean Information

Coffee producing countries: Africa, Ethiopia

Coffee estates: Guji Guji, HambellaWamena district, Dimtu city, Buku able estate

Production altitude: 2250~2350m

Green Bean Grade: G1

Treatment: Natural Sun (African Sun Bed)

The performance of the flower in the cup test:

In Forte-BG grinder grinding degree 5M (Chinese standard No. 20 sieve pass rate 88%) cup test flavor performance: rose flower fragrance, strawberry jam, peach pulp, black tea tail.

While in Huijia ZD-10 grinding degree 4.2 (Chinese standard No. 20 sieve passing rate 87%), the cup test flavor performance is: honey, flower, citrus, chocolate, wood.

In the cup test, the flower head with flat knife shows rich floral and fruit aroma, and the taste is relatively clean; while in the cone mill, the performance is sweet with a little chocolate bitterness, slightly with some woody miscellaneous taste, which may be caused by fine powder. What about the performance of the flower head in brewing?

Performance in brewing:

Xiao Bian used the Forte-BG bean grinder adjusted yesterday to grind 5R and Huijia ZD-10 grinding degree 6, and made a brewing comparison of [Huakui].

Water temperature 91℃, powder-water ratio 1:15, V60 filter cup

Flat knife cutter plate: first 30g water steams for 30 seconds, after injecting 122g water, wait until the water level drops to quickly see the powder bed, and then inject water to 228g, in order not to affect their water-powder ratio, Xiaobian will remove the filter cup after the water is completely filtered. The total brewing time is 2 minutes and 13 seconds.

Grinding degree of conical knife disc 6: steam 30g water for 30 seconds, inject 120g water after the water level drops to almost see the powder bed, inject water again to 223g, the total brewing time is 2 minutes and 10 seconds.

The flat knife disc shows the flavor of flowers and fruits, cream, nuts, hazelnuts, prunes and black tea. The taste is clean and the aftertaste is sweet.

Cone knife wheel grinding 6 performance flavor: orange, floral, berry, maple syrup, flavor round taste balance.

After comparing the two, flat knife will have more layered nutty flavor, cone knife will be sour and lively, nut flavor is not prominent. Therefore, adjust the grinding degree of the conical knife disc a little bit to approach the flavor of the flat knife and brew again.

Grinding degree of conical knife disc 5: first 30g water steams for 30 seconds, after injecting 120g water, wait for the water level to drop to almost see the powder bed, and then inject water to 227g, in order not to affect their water powder ratio, the total brewing time is 2 minutes and 10 seconds.

Cone knife wheel grinding degree 5 performance flavor: chocolate, cream, citrus, floral, tail rhyme tea.

Compared to the taper cutter head grinding degree 6, grinding degree 5 will be closer to the overall flavor of the flat knife.

Due to the difference between the cutter head and the use of different machines, so Xiaobian can only be as close as possible. Summarize the whole correction process below, first of all, there is a bean grinder that can be used as a reference (if there is no small series, please use the hand and vision to observe it), then compare the passing rate between them, try to make them consistent, and then make a brewing comparison, feel the difference between them, and then fine-tune. Just like Huijia ZD-10, it will have more fine powder when using the conical cutter, but the overall particles are larger, so Xiaobian adjusts the grinding degree to 5 to make the flavor close to the flavor brewed by the flat cutter Forte-BG bean grinder, so that the whole calibration process is completed. (If you don't want too much fine powder when using Huijia ZD-10 daily, you can buy a powder sifter)

How to determine the grinding degree of a newly bought bean grinder?

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