November 17, 2017

Brew Guide: How Does Pulse Pouring Affect Extraction?


If you want the best possible coffee, you can’t overlook the importance of your drink’s biggest ingredient: water. Temperature, quality, chemical composition, distribution method… it all affects the flavours, aromas, and extraction rates of your brew.

So today, we’re taking a look at one of specialty coffee’s most celebrated water distribution techniques: pulse pouring. We’ve spoken with Patrik Stridsberg, Co-Founder of 3TEMP and co-designer of the Hipster brewer, to find out more.

Lee este artículo en español Guía de Preparación: Vertido por Pulsos y Cómo Afecta a Tu Café

Measuring weight of dry ground coffee in batch brewer basket before extraction

Weighing the grounds in a 3TEMP Hipster brewer. Credit: CleverCoffee

Water Distribution: The Different Methods

There are many different ways to distribute your water. The simplest is just to pour it all at once and wait. For immersion brewing, this is the recommended method: it ensures that the grounds and water molecules all have the same (or as close to the same as possible) amount of contact time.

With drip/filter brewing, because the water is trickling through the coffee, you can use continuous pouring or pulse pouring. Continuous pouring requires exceptional control over your pour speed (good arm muscles can help as well, if you’re doing this all day long!) Pulse pouring means using multiple pours of specific amounts of water. You can experiment with the volume of water and number of pours.

These methods help prevent grounds from rising up the side of the filter, i.e. they avoid agitating the coffee bed too much. However, they also create some positive agitation: they gently disrupt the grinds, causing them to move about and therefore ensuring a more even contact between them and the water molecules. More on the relationship between agitation, pouring, and extraction to come!

SEE ALSO:Brew Guide: What Are The 3 Phases of Drip Coffee Brewing?

When brewing manually, you can also choose to pour in concentric circles. This will help to create more consistent agitation and ensure an even wetting of the grounds.

Pouring water onto coffee grounds in pourover brewer

Pouring water over ground coffee. Credit: Tyler Nix

Extraction Basics

Before we look at pulse pouring, extraction, and agitation in general, let’s quickly recap extraction.

Extraction is a delicate balance of grind size, roast level, water temperature, coffee weight, water volume, brew time, and more – but what it really comes down to is the amount and efficacy of contact between the coffee grinds and the water molecules.

The more contact, or the more effective the contact (whether due to smaller grinds, more brew time, or higher brew temperatures), the more flavour and aroma compounds are extracted. The less contact, or the less effective the contact, the less is extracted.

Remember: controlling extraction is the key to delicious coffee. Over-extracted brews will be bitter and astringent. Under-extracted brews will be sour. And unevenly extracted brews will be a mixture of the two (and also impossible to replicate). This is where agitation becomes important.

SEE ALSO: Understanding Coffee Extraction & Other Key Brewing Concepts

Pulse Pouring, Agitation, & Extraction

Patrik explains that pulse pouring can affect agitation and determine brew time, using the Hipster as an example. “We can choose the size of the pulses. Fewer pulses equals more water in each pulse. More pulses equals less water in each pulse. If we have few pulses, the water hits the bed harder [because there’s more of it] and we have a shorter extraction time, and more pulses gives us a longer extraction time.”

In other words, it’s not just about how much water and how often: it’s also about how hard.

If the water hits the coffee bed too hard, and with too much volume, it can agitate the grinds too much as well. This is particularly true if you’re using a fine grind: the lighter weight will allow the ground coffee to be more easily displaced.

So what is “too much agitation”? For most professionals, it’s when the coffee bed isn’t even after the water has finished dripping through the grounds. Water will automatically trickle down to the area of the bed that is the least densely packed and make its way through there – meaning over-extracted coffee in some areas and under-extracted coffee in others. You want your bed to be as even as possible both before and after the brew.

SEE ALSO: What Is Agitation & How Does It Make My Filter Coffee Better?

“In all brewers,” Patrik tells me, “if you want an even coffee bed, water distribution needs to be over a longer time.” This will mean more pulses of smaller volumes of water which will hit the coffee bed more softly and, in turn, cause gentler agitation.

Batch brewer extracting filter coffee

Brewing coffee on a 3Temp Hipster brewer. Credit: CleverCoffee

Pulse Pouring, Extraction Time, & Grind Size

But as we said before, extraction is a balance of many variables. The good news is that, by manipulating your pulse pours, you can change one of the other variables without negatively affecting the extraction.

Say you wanted to keep to a particular brew time but change the grind size. Normally, the grind size will affect the brew time: the coarser the grounds, the slower the extraction and the faster the water drips through. However, with smaller pulses, you can use a smaller stream of water and therefore a longer brew time, regardless of the grind size.

Patrik tells us, “Usually you have to adjust the grind size to be able to get the water to run faster or slower.” However, by making pulsing a parameter – as the team at 3TEMP did with the Hipster – you can break, or weaken, the relationship between grind size and brew time.

Pouring water over coffee grounds in pourover filter basket

Slowly pouring water for a Kalita brew. Credit: Aryan Joshani

Consistency vs Flavour

So is pulse pouring in concentric circles the best method? Well, it’s worth mentioning that your pour choices will to a certain extent be dictated by your brewer, who you’re making coffee for, and more. One thing to remember is that pulse pouring and concentric circles can result in more even extraction but they’re also harder to do consistently.

Patrik tells me, “When you hand brew, it’s almost impossible to get it exactly the same every time. There are very few people who command that much control.”

On the other hand, he points out, “One thing that you can do with hand brew, you can work the water into the coffee any way you like. With the batch brew, we can only open the shower and it can hit the water either hard or light… So we don’t have this control over the water distribution and I think that’s not possible with batch brewing. I think you will always have better control when you do it by hand, but it will not be consistent.”

What’s more important: control or consistency? That will depend on the situation. Are you making coffee for yourself? Are you training a team of baristas for a busy coffee shop? Are you competing? You need to determine your priorities.

SEE ALSO: How to Serve Consistently Good Coffee in a Café

Cup of black filter coffee

Black coffee, ready for drinking. Credit: Dan Gold

Water distribution is just one of many fascinating variables that can affect your coffee extraction. Experiment with the methods we’ve looked at above, discover what works for you, and don’t be afraid to change it with every new coffee.

Please note: This article has been sponsored by 3TEMP.  

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