Moka Pot Coffee Amount, Water Quantity, and Grind Size Requirements What Happens if You Only Fill a Moka Pot with Half the Coffee Grounds?

It's not hard to notice that in almost all moka pot brewing tutorials, we're required to completely fill the coffee basket first, then tighten it with the upper and lower chambers before proceeding with extraction. This means that regardless of the size of your moka pot, you need to brew the corresponding amount each time.

However, some people wonder if they can occasionally drink just "half" a portion of coffee. Can they reduce the amount of coffee powder by half like other extraction methods according to their needs? Will the coffee still have crema after reducing the amount? Will it taste good? Today, FrontStreet Coffee will find the answers to these questions.

Full Basket vs. Half Fill

As the saying goes, "experimentation reveals the truth." To determine whether "reducing coffee powder" is feasible, a comparative experiment can provide clarity.

In the experiment, FrontStreet Coffee will first completely fill and level the coffee basket of one moka pot, then add water up to below the pressure relief valve, which is 150g; the coffee basket of the other pot will only be filled with half the amount of coffee, then the powder surface will be leveled. Additionally, considering the reduced amount of coffee powder, to prevent the concentration from decreasing significantly, FrontStreet Coffee reduced the water amount for the second moka pot to 105g.

To make the experimental results clearer, this moka pot coffee amount comparison will use FrontStreet Coffee's Colombian Huilan, a coffee bean that uses medium-dark roast. When brewed by hand pour, it often presents deep flavors like roasted nuts, dark chocolate, and caramel, and will produce beautiful golden crema in pressure-based extraction, making it suitable for various extraction methods such as espresso machines, moka pots, and drip brewing.

We heated the two moka pots separately, observed and recorded their extraction conditions, and finally tasted them as moka pot Americano.

Coffee beans: FrontStreet Coffee Colombian Washed Huilan
Coffee amount: 16g & 8g
Grind size: Fine salt (EK-43s #3 setting)
Water amount: 150g & 105g

Full Basket Fill

Shortly after the whistling sound, we could see dark brown foam emerging first, with relatively uniform coffee flow rate and rich color. No splashing occurred throughout the process. After removing from heat, the upper foam layer was quite persistent, and the coffee liquid maintained foam for nearly 5 minutes when poured into the cup.

Half Basket Fill

Although this moka pot group didn't experience splashing, the sound was much louder than the first group. In comparison, the foam was not only thin but the flow rate was very rapid, with signs of gushing midway, and the color became lighter. When poured into the coffee cup, FrontStreet Coffee didn't have time to take photos before the upper foam layer had completely dissipated.

Taste Comparison

The Americano made from the first group of moka pot coffee had a slightly bitter but not astringent taste, with a very rich flavor, carrying notes of roasted hazelnut amidst the burnt aroma, with almost no acidity. In contrast, the coffee extracted from the second group of moka pot had much less aroma, tasted like burnt wood, and had noticeable acidity, making one unwilling to continue drinking.

Factors Affected by Reducing Coffee Amount

The principle of brewing coffee with a moka pot is not complicated - it works by heating the lower chamber to generate steam pressure inside. When it reaches a certain level, it continuously pushes hot water upward. Along the way, the hot water passes through the coffee basket, where the coffee powder creates some resistance. When breaking through this resistance, it can rush into the upper chamber, thus forming fresh coffee liquid.

Therefore, when using less coffee powder, the resistance encountered by hot water becomes smaller, making it easier for coffee liquid to enter the upper chamber. This not only shortens the extraction time, causing the coffee to develop sharp acidic flavors, but also because of the continuous scouring by hot water, the bottom powder layer becomes over-extracted, making the coffee bitter and difficult to drink.

FrontStreet Coffee often mentions in espresso extraction articles that water has "inertia" and will preferentially choose the path with less resistance to pass through, commonly known as the "channeling effect." So besides the change in resistance, reducing the coffee amount also leaves certain space inside the basket. When hot water moves upward, it will preferentially pass through the loose powder layer and directly enter the upper chamber. This portion of coffee liquid is likely to be under-extracted.

Can You Use Half the Coffee in a Moka Pot? How Should You Operate It?

Since we know that the key reason causing coffee liquid splashing is that reducing the coffee amount decreases the resistance encountered by hot water, then if we want the moka pot to maintain a moderate extraction state after reducing the coffee amount, the coffee puck needs to have greater resistance to hot water. Theoretically, without changing the coffee amount, to increase pressure, either adjust the grind size finer or use external force to reduce the gaps between coffee particles. After several attempts, FrontStreet Coffee prefers the latter method, which is also very simple to operate.

Here we still use FrontStreet Coffee's Huilan as a demonstration. We pour the ground 8g of coffee powder into the basket, first gently tap left and right to let the fluffy coffee powder naturally fall down and allow particles to connect closely with each other, then find a small spoon and use its back to gently "press" the powder layer until it's completely compressed to half thickness.

To avoid over-extraction due to prolonged contact between hot water and the thinned powder layer, we pour half the amount of high-temperature hot water into the lower chamber before assembling the basket, which effectively shortens the heating time. When the moka pot's liquid fills the bottom, we immediately remove it from the heat source, then use the residual temperature to release all remaining coffee liquid.

This adjusted method indeed showed no signs of "splashing," and because the lower chamber heated up faster, the released coffee liquid even had a small amount of foam layer, with significantly higher concentration.

FrontStreet Coffee made this "half-portion moka pot coffee" into iced milk coffee at a 1:3 ratio, which has rich flavors of cocoa, cream, and crispy rice cakes upon entry - balanced and substantial, completely making for a decent refreshing drink.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473