A bit of a different newsletter...
I've never recommended a coffee podcast before but there's a first time for everything. I recently came across a podcast called The Science of Coffee. This is a spin off series from Filter Stories which is a documentary podcast by James Harper. There's a lot to like about James' podcast. He has a euphonious voice, it's paced well, the focus is on the microscopic secrets of coffee, the music in the background is composed and played by James, and, by the way, he once had a career in finance and investment banking. If you know me then you'll understand why I think he's an interesting person!
The particular podcast episode I'll point to is called 'Coffee Extraction'. Please see a link below to a website where you can listen to the podcast. I listened to it on the Apple Podcast app.
Science of Coffee Podcast Link
In this episode, James focuses on a couple of dimensions of coffee extraction which change how coffee tastes. The general finding is that weaker coffee brews are perceived to be sweeter. James cites research by the Specialty Coffee Association as well as the UC Davis Coffee Centre. In order to counteract bitterness and amplify sweetness, you can simply make coffee weaker!
James goes on to discuss a construct known as the Brewing Control Chart the application of which is being revisited by the coffee industry. This chart has two dimensions. The vertical dimension represents brew strength and the horizontal direction represents extraction yield. Brew strength is measured in terms of the total dissolved solids in the extracted coffee relative to the volume of that coffee. Extraction yield is a measure of the proportion of coffee material that you have managed to extract into your coffee - how much of the coffee goodness you have removed from the original dry coffee grounds. Traditionally the Brewing Control Chart has suggested that a single point on the chart represents the optimal brew.
People in the coffee industry are now suggesting an approach with a wider spectrum of applicability. If you want to maximise sweetness in your coffee then move to the bottom left of the chart. You do this by adding more water relative to coffee and thereby reducing brew strength. You can also think about searching for other characteristics in your coffee... sour, bitter, floral... according to your preferences. Extraction yield is proportional to the temperature of your brew water. If you increase the temperature you increase the extraction yield, conversely if you decrease the temperature you reduce the extraction yield.
For a sour bomb go towards the top left of the chart - a strong brew extracted with low temperature water.
To increase bitterness go to the top right of the chart - strong brew extracted with high temperature water.
To find more floral notes go to the bottom right of the chart - a weak brew extracted with high temperature water.
I'm going on this particular journey one step at a time and have experimented with making my espresso shots longer. Instead of 27 g of espresso I'm now producing 45 g with the same amount of coffee grounds in the portafilter. The result has been some really lovely espresso, sweeter, less bitter, but still with great texture.
If you decide to shake up some of your brewing variables then please let me know what you discover.
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