UCC Australia’s Babin Gurung on how to analyse espresso extractions

espresso extraction

UCC Australia’s Babin Gurung explains how to use your senses to analyse espresso extractions and trouble shoot solutions to maintain coffee quality in your café.

As a barista, most of your time revolves around getting your espresso to taste right. It is important to use all cues to analyse espresso quality and create a benchmark for the espresso you’re serving. This means anything that falls outside the range needs to be addressed. But finding issues with your coffee is half the work. The other half is fixing the problem before you remake that coffee. So, today let’s look at how to create a benchmark for your coffee and look to find solutions for any quality issues you may encounter.


The roast profile of your coffee will dictate the colour of your espresso and crema, which means a deeper darker colour for darker roasted coffee should be expected compared to a more golden colour for medium to light roasted coffee. The espresso should pour evenly from the spouts and have thick, full, viscous consistency. Remember, fresher beans contain higher Co2 gas and therefore will produce more crema and release pockets of air as it pours from the spouts.


For espresso, hearing provides very little cue to the quality, but it is important to listen for any unusual sounds coming from the machine or the grinder. There should be a clear sound when you press the shot button with few seconds delay before the shot begins.


Fragrance refers to the smell of dry coffee and aroma is the smell of brewed coffee. Freshly roasted coffee should give off pleasant fragrance and clear aroma. The smell, once again, should reflect the origin and roast profile of the coffee. Some examples of good coffee smells include, nutty, chocolatey, fruity, etc. Rancid and acrid smells include smoky, rubbery, and leathery, which could signify issues with the beans, roasting, freshness, or extraction.


Referring to the flavour notes provided by your coffee roaster is always a good reference point when tasting coffee. But regardless of what coffee it is, your espresso should have a smooth balance of sweetness, acidity, and bitterness. A long-lasting sweetness in your palate is indicative of good espresso while lingering bitterness can mean issues with the coffee or its preparation.


Tactile, also called mouthfeel, is a good way of assessing coffee. Coffee can have heavy body and texture or light and clean mouthfeel. It is important to understand the difference between the two as they give you very different experience of drinking coffee. Your coffee needs to provide the right level of mouthfeel to match the flavour profile.

Now that you have a clear idea of what attributes your espresso needs to have, let’s look at some common issues you may come across.

Bitter/Burnt: Natural bitterness can add to the flavour and complexity to a coffee but when the bitterness overpowers the characteristics of a coffee, it is often a sign of a problem in your espresso. Excessive bitterness can come from:

  • Stale beans: Coffee beans after roasting starts to degas and open more surface area for extraction. The ideal time to consume coffee after roasting is between seven to 28 days, which means coffee that is older can lose its aroma and easily over-extract. This process is accelerated if the beans are left in the open, under direct heat and sunlight. Open coffee in the hopper or dosing chamber can absorb smell from its surround, so it is important to only put as much coffee as you need for two hours of service and keep remaining beans inside the bag and sealed into an air-tight container to prolong its freshness.
  • Over-extraction: Over-extraction refers to unwanted solubles getting extracted from coffee causing harsh bitterness. Besides stale beans, over-extraction can occur when you overdose coffee in your group handle or when the grind particles are too fine, both of which slows the pour and creates long contact time between water and coffee. Regular grinder calibration is the key to maintaining ideal dose, extraction time and water volume. Refer to BeanScene’s April 2021 issue for step-by-step calibration guide.
  • Dirty equipment: Regular cleaning is important to avoid coffee buildup in your group head and handle. Any coffee that is left behind will continue to heat from the machine resulting in acrid unpleasant bitterness. The best way to remove all buildup is by using espresso cleaning chemical at least once every 24 hours. Some of the ways to maintain cleanliness throughout the day is by purging between shots, rinsing group handles at regular intervals, and scrubbing group heads with a cleaning brush.

Sour/Acidic: The right level of acidity is favourable in coffee which can add brightness and character, but high levels of acidity or sourness can be negative. Sourness is often caused by:

  • Bean freshness: Unlike old, stale coffee which can give over-extracted flavour, beans that are too fresh have high levels of Co2 gas, which can interfere with optimum extraction. This often results in coffee that is uneven, lacks balance and can be acidic in flavour. Around seven days of resting is ideal to allow some of the gas to escape resulting in consistent shots.
  • Under-extraction: This is the opposite of over-extraction where not enough solubles are getting extracted from coffee resulting in acidic, imbalanced, and weaker flavour. This happens when you under-dose coffee in your group handle or grind particles are too coarse. Following the recipe and calibrating your grinder is the best way to manage extraction issues.

Bland: Bland is a very vague way to describe a coffee and it could mean few things:

  • Milky: This refers to milk-based coffee not having enough cut-through of coffee flavour. Lighter roasted coffees therefore aren’t ideal for milk based as they tend to taste weaker against milk. An under-extracted coffee can have lower intensity as well which then mixed with milk can get further diluted lacking the cut-through. This can be fixed by calibrating the grinder regularly. Also, when pouring milk into the espresso, it is important to retain most of the crema. Coffee where crema is washed or blended aggressively can taste milkier than a coffee with sharp well- maintained crema.
  • Watery: A widely accepted brew ratio for espresso coffee is 1:2 to 1:2.5 coffee to water ratio. Higher ratio often produces weaker and sometimes watery coffee. Therefore, it is important to regularly check the volumetric on the coffee machine and ensure the dose is correct. This could also occur due to channeling where small gaps or cracks in your puck can lead to water channeling through the bed of coffee rather than extracting evenly. Proper grinding, distribution and maintaining water pressure are some key areas of focus to avoid channeling.

It is very important to keep assessing your coffee throughout the day as changing weather, over-use of equipment, difference in roast date can create inconsistency in coffee. Using the above cues and listening to your customers and troubleshooting will be key to maintaining high quality coffee in your café.

This article appears in the October 2022 edition of BeanScene. Subscribe HERE.

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