Moccamaster KBG 741 Coffee Machine Test – As Good as Its Reputation?

The Moccamaster has an almost legendary reputation. It is valued for its design, craftsmanship, durability, and the quality of the coffee it produces. This piqued our curiosity. We put the brewer through an intensive test. We tested 40 brews with different coffees, brew ratios, and quantities.

Our results are considerably more nuanced than the many positive online reviews. But let's take it one step at a time. As coffee makers, one thing is paramount for us above all: the quality of the coffee in the cup.

The following parameters are crucial for this: the temperature of the brewing water, the distribution of the brewing water over the coffee, and the rate at which the coffee water is applied.

The choice of coffee and grind size are important, but cannot be controlled by the machine. Nevertheless, we offer tips for suitable coffees and an appropriate grind size.

Moccamaster Instructions – One Button for Coffee

Operating the Moccamaster KBG 741 is really as simple as it gets. In this respect, the Moccamaster hardly differs from most other filter coffee machines. Insert the paper filter, weigh out the coffee, pour water into the permanently mounted water tank, and start with the push of a button. We wouldn't be coffee makers if we didn't refine these instructions.

We generally recommend rinsing the paper filter thoroughly with hot water. This reduces the paper taste that would otherwise overpower the coffee later. A positive side effect is that the coffee filter paper then adheres better to the edges of the filter holder. This reduces the likelihood of the paper filter folding inward and water bypassing it. You can't rinse too much water through, but 300 ml is ideal.

Then add the correct amount of ground coffee. The right dose depends on the desired drink quantity. A good standard value is 60 grams of coffee per liter of water. In a detailed blog post we discussed this in more detail.

We initially made two brews. 18 grams of coffee and 300 ml of water, and 60 grams of coffee and 1000 ml of water. Each quantity was applied. We also weighed the water. With the push of a button, we started the brew. We compared these two brews by taste.

18g and 300 ml vs. 60g in 1000 ml

In a comparative blind tasting of the two brews, the brew with the larger volume performed significantly better. Better in this case meant that the coffee tasted more balanced and homogeneous. It was also significantly stronger, i.e., more robust in flavor. The 18g/300g brew had, on the one hand, a slightly unpleasant acidity and, on the other hand, lacked the complexity and expected flavor notes of the coffee.

We adjusted the grind size of the 18g/300g slightly finer and made further brews. However, the results did not improve significantly. As you can see in Table 1, the strength in particular—that is, the concentration of dissolved coffee particles—was relatively low at just over 1.0% on average. This value can be measured with a refractometer. A desirable result is around 1.1 – 1.5% strength (TDS = Total dissolved solids), with the rest of the beverage being water. Normally, finer grind sizes increase the resistance in the coffee, which leads to slower drainage of the brewing water and thus more intensive extraction. However, by refining the grind size, we were unable to achieve significantly stronger brews with the amount of coffee and water used.

Table 1.

The target extraction rate is 18 – 22%. Extraction refers to the portions of the coffee bean that are extracted. When higher extractions are achieved, the strength in the cup is also more pronounced. These two values are therefore dependent on each other (see also blog post on Strength and Extraction).

Table 2 shows the results of the 60g/1000g brew. Here we achieved stronger results at the same brew ratio. The strength averages over 1.2% TDS, which is in the target range. Correspondingly, the extraction is in the target range in two of five brews. In theory, we could have increased extraction with a finer grind size. However, the drainage through the filter was too slow and the water level was at maximum. A finer grind would have caused the filter to overflow.

Table 2.

The comparison of the brews shows that the extraction yield of the Moccamaster is better with larger brew volumes. This is mainly due to the distribution of water over the coffee bed. With larger brew volumes, the brewing water better captures all coffee particles and washes them out more effectively. This is primarily due to the design of the brew head.

The Well-Intentioned Brew Head

Almost all classical filter coffee machines have the problem that the brewing water continuously drips onto the same spot in the coffee bed – usually right in the center. At this location, the ground coffee is heavily agitated with each drop and bubble and extensively extracted by the constant influx of water. Meanwhile, many other coffee particles on the edge of the coffee bed relax and watch the extraction party in the center.

It doesn't take much to brew filter coffee well – except for even extraction. This is achieved when as many coffee particles as possible are in contact with water equally intensively and for the same length of time. Those who brew by hand practice this technique precisely. Evenly wet everything and agitate it – that gives delicious coffee.

Moccamaster understood the principle and developed a rod-shaped brew head with 9 holes. This is supposed to distribute the brewing water evenly over the coffee bed. Supposed to, because at least on the device we tested, it doesn't work. The water flows into the brew rod and drips out mostly through the front holes. Ultimately, however, where the water exits is secondary, since the water below the brew head combines into a single, connected stream.

We changed the slope of the brew rod to rule out whether this might be due to a slanted table or something similar, but we consistently arrived at this result.

The consequence is that the brewing water extracts predominantly in the center and a larger portion of the coffee bed is not evenly saturated. With larger water quantities – which is why the 60g/1000ml brew was better – this plays a subordinate role because a water bed forms over the coffee grounds anyway. But even in this case, extraction is not even.

This malfunction surprised us. The brew head with multiple outlets shows the right principle. However, the distribution of water is not pronounced enough to provide a significant improvement.

Improving Brews Through Agitation

When the brew head doesn't do what it should, the techniques of hand brewing come into play. Simply stirring the coffee after about 20 – 30 seconds of brew time leads to significantly better brew results. If you repeat the stirring once the entire amount of water has been added, the brew results are noticeably more homogeneous and tastier.

Table 3

Table 3 also shows a noticeably longer brew time. This occurs because now the entire coffee creates resistance. By stirring at the end of the brew, you intentionally create rotation that draws coffee particles from the edges into a vortex and keeps them rotating throughout a larger part of the brew.

Moccamaster Brew Temperature

Generally, the brew temperature should be constant. Exceptions prove the rule. There are coffees that simply taste best when brewed at 80 degrees. In my filter coffee courses, I almost always do the test: participants brew the same coffee at 50, 60, 70, 80, 90, and 100 degrees. There's a clear tendency that the coffee tastes best when brewed at 90 degrees. Time and again, individual coffees also perform well at other temperatures. A brew temperature of 92 – 94 degrees is the most popular brew temperature across all brews.

The Moccamaster brews very consistently – but slightly too high in temperature. It heats up incredibly quickly. Even on the first brew of the day, it's ready to brew in less than 20 seconds and the first water drops drip onto the coffee.

We measured the temperature directly at the water outlet. The first surge of water dripped onto the coffee at a water temperature of 60 degrees. However, this was only a few milliliters, probably cooled by heat exchange with the metal brew rod. Subsequently, the Moccamaster brews very precisely and consistently at 98 – 99 degrees at the outlet throughout the entire brew cycle. The impact temperature is hardly lower because the brew head is close to the coffee. In other words: the brew temperature is very high – too high for many coffees. These high temperatures tend to intensify bitterness in coffee.

98 degree brew temperatures are certainly an option for very clear and lightly roasted coffees that inherently carry little bitterness and are very transparent. For the vast majority of coffees, however, this temperature is too high. It becomes particularly problematic for all coffees that are not specialty coffee and are more darkly roasted. A brew temperature of around 90 degrees or less would be the best choice.

Surge Brewing vs. Continuous Brewing and Pre-Brewing

The Moccamaster brews continuously from the first to the last drop. From the start of brewing, water is applied in a steady flow. We tested the flow rate with the interesting scale from Black Mirror. The scale actually consists of two scales. It measures, on one hand, the weight of water being applied to the filter and, on the other hand, the amount of brewed coffee already in the pot.

Continuous brewing is well suited to deliver consistent results from extraction to extraction. Surge brews, also called pulse brews, apply water in bursts. An initial burst serves as a pre-brew. At this point, a small amount of water is applied. The CO2 created by the roasting can escape. CO2 is not tasty on one hand, and on the other hand, its release causes agitation in the coffee bed. This so-called blooming is especially useful for darker roasts since they have significantly more CO2 bound in them.

Another reason we recommend using the Moccamaster primarily for lighter roasts.

The following graph shows two brews we captured with the Black Mirror App. On the left was brewed with the Moccamaster, on the right by hand.

Conclusion and Outlook Moccamaster KBG 741

We examined the Moccamaster thoroughly. The Moccamaster is the third filter coffee machine we're testing in a series of coffee machines. Our background is manual brewing. The author was a Swiss Brewers Cup Champion (filter coffee master) and multiple runner-up. The standard for good filter coffee is high – but not so difficult to achieve. As mentioned at the beginning, a few basic parameters need to be met.

We examine automatic filter coffee machines because we expect that for the future, an automatic machine will be able to better deliver consistency across many brews in succession – with consistent quality.

The Moccamaster is not yet this machine. Compared to hand-brewed filter coffee, the Moccamaster delivers satisfactory to good results with light roasts and poor to satisfactory results with dark roasts.

Its temperature is very consistent – but unfortunately too high. The distribution of water is well conceived but doesn't work sufficiently in practice. The machine's biggest pro is its excellent build quality and 5-year warranty.

These tests were conducted with our test device, which we purchased, like all other test devices.