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Changing Espresso Extraction With Scott Rao
How Scott Rao is redefining espresso extraction and producing great results with higher extraction times.
Published December 17, 2021
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Erik Hedlund
Coffee experts@The Coffee Lab
Scott Rao is a coffee professional who is known for diving deeper into several different aspects of specialty coffee profiling, in particular, espresso extraction time. Scott has been sharing several data points on his social media and blog since 2016 to show the different possibilities of making great-tasting espresso with shots that are pulled in more than sixty seconds, containing twenty-five percent more coffee grounds with brew ratios of 1:4 and 1:3. He used a DE1 espresso machine and worked alongside John Buckman, founder of Decent Espresso, to get the results, measuring the espresso machine flow rate.
Across the US, the current standards for espresso are defined by a 25-30 second shot using a ratio of 1:2 coffee to water. One of the main reasons for these standards is due to Espresso Coffee: The Science of Quality, a book written by Andrea Illy in 1995. In the book, Illy suggests that espresso extraction should have a 1:2 ratio of coffee to water and be brewed for around 30 seconds. According to Illy, anything less is likely to be under-extracted and sour. On the other hand, anything that is brewed for longer than thirty seconds will be over-extracted and burned. However, Scott is trying to prove that a higher extraction time does not always burn the espresso and leads to an astringent taste. With a longer extraction time or a lower coffee to water ratio, the espresso can still taste great when brewed under the right circumstances.
Scott’s Experiments
As seen from the experiments carried out by Scott, highly extracted coffee profiles are described as a longer pre-infusion of the coffee with the pressure gently ramped to climax, then followed by a slow decline in pressure until the ratio of 1:4 or 1:3 is achieved. A pre-infusion will last for at least thirteen seconds, which is followed by thirty to forty seconds of the water flow pressure decreasing. Overall, the duration of the shot lasts for at least sixty seconds. This results in a shot with at least twenty-five percent coffee soluble, producing the best taste for any type of coffee. According to Scott, the shot tastes better with these high extraction profiles. He said that when people came to taste the super high extractions with their own coffee at his World of Coffee booth, he got overwhelmingly positive feedback.
DE1 Espresso Machine
To create these super high extraction profiles, Scott uses a DE1 espresso machine, which is exclusively operated from an Android tablet and provides a live feed of the extraction process. It enables the user to easily make changes to a range of variables including the flow rate, pressure profile, and water temperature in real-time. However, according to Scott, baristas do not need a very sophisticated coffee machine such as this one to achieve the same results. He said that while it might be harder to achieve on another machine, it is not impossible since a good highly extracted espresso shot is based more on the preparation of the espresso and how knowledgeable the barista is when it comes to the coffee and the machine that they are using.
Espresso Variables
According to Scott, while all of the variables involved are important to the process of extracting espresso, there are some that are more important compared to others. He said that a good highly extracted espresso is defined by how well the particles are distributed and how well the puck is prepared. This means that the grounds in the portafilter are distributed evenly and allow for the water to flow consistently. Scott says that the distribution of the grounds is a major factor when it comes to separating a good shot from a bad espresso shot, and it is all about how they are distributed in the puck. Scott recommends using a grind distribution tool to make sure that the grounds in the portafilter are evenly spread, along with making sure that you use a grinder that produces consistent grounds for every shot. This helps to avoid espresso over extraction and a nasty over extracted espresso taste.
Redefining Espresso Extraction
Scott is redefining espresso extraction in the industry of specialty coffee, with his approach potentially going to lead to more sustainable business practices. For example, by using higher extraction techniques, coffee businesses could use less coffee and still make better-tasting coffee. For roasters that also have coffee shops, for example, this could mean that over time they would be able to reduce the amount of coffee that is brewed in the café, spending more money on better quality green coffee as a result. Along with this, coffee shop chains, independent businesses, and cafes could also use the money that they save by using less coffee on investing in better equipment and more employee training.
Influence on The Industry
Scott’s experiments with the profiling software and higher extraction espresso shots have the potential to influence manufacturers of coffee machines, coffee shops, baristas, and other professionals to adopt these extraction methods and flow profiles to improve on norms that have been set by leaders in the industry, such as Andrea Illy. However, what Scott is making more apparent is that coffee is subjective and has lots of different variables that are subject to constant change. According to Scott, feedback and data are absolutely essential to getting better at being a coffee professional.
The Basics of Coffee Extraction
In order to get a better understanding of Scott’s experiments with a higher extraction, it’s important to understand how coffee extraction works. No matter the method of coffee extraction that is used, coffee requires a solvent, and water is one of nature’s best solvents for its chemical properties.
The best way to extract the molecules inside of the coffee beans is to ensure that there is as much contact surface as possible to allow the water to get close and extract as many flavors as needed. Once the coffee is ground, it’s time to go on to the extraction. This is where getting the dose is especially important.
The type of beans that you use will play a part in this. You will need more grams of coffee if using Arabica rather than Robusta beans. Arabica beans tend to be thicker and less soluble compared to Robusta beans as they are grown at high altitudes. In general, a higher temperature tends to work better for Arabica beans compared to Robusta beans.
The Yield
An important part of coffee extraction is the yield, which refers to the weight of the liquid obtained in the cup. More or less yield simply means more or less liquid in the cup. More yield will have less body and flavors and be more bitter, compared to less yield, which tends to be more sour but will have more body and flavors. Twice the amount of water compared to the dose that is ground is the standard yield. For example, if you grind 20g of coffee, it should have a yield of 40g.
Coffee Extraction Time
The coffee extraction time is related to a number of variables including the coffee dose’s grind size, the bean’s roast profile, the amount of coffee dose, and the yield, which all work together when it comes to the extraction time of the coffee. Making the grind size coarser or finer is generally the main way that the extraction time is changed. When the grinds are coarser, the surface area is increased, making it easier for the water to pass through the coffee base. There is not enough resistance, and some of the flavor compounds that are needed to balance the cup will not be extracted. If the variables are not adjusted to accommodate for this, it can lead to an under-extracted cup of coffee that lacks complexity and sweetness. On the other hand, finer coffee grounds minimize the surface area of the coffee, making it harder for the water to pass through the coffee base. When this happens, if the variables are not adjusted accordingly, there will be too much resistance, and the water will extract too many flavor compounds, including the ones that you don’t want in your cup. This tends to produce a cup that is more bitter and lacks the sweetness and acidity that you want in your coffee.
Tips for Extracting Espresso at Home
Making great espresso is both an art and a science. If you want to make espresso at home, it’s important to get the basics right before you consider experimenting with higher extraction times. To make the right espresso, it’s important to cover all your bases including making sure that you have the right coffee, the correct equipment, and the right technique. The first thing to do is make sure that you have got the right coffee beans – look for freshly roasted beans from reputable roasters. The right tools, such as a burr grinder, will produce consistent grinds every time.
While 25-30 seconds is the standard extraction time for espresso, Scott Rao is showing that with the right circumstances, you can get great-tasting espresso with a higher extraction time of sixty seconds.
About the author
Erik Hedlund
With Era of We and The Coffee Lab, I hope to share knowledge, increase the value of coffee – and secure the future of coffee.
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