Advanced Coffee Making

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ACM 4.01 – A Fixed TDS

A Fixed TDS

If you have a fixed brew ratio and manipulate extraction by changing the grind, you’re changing the strength of your coffee as you change the extraction yield. By incorporating a shift across to a new diagonal line on the brew control chart, more consistency is gained while maintaining the same TDS. Our idea of best practice is to navigate the coffee control chart horizontally, not vertically.

Increasing extraction with a fixed TDS

Here are a few more examples from a cafe environment of how to navigate horizontally:
  • You have established a TDS target at 10% for espresso by blind tasting and measurement.

  • You are brewing on your established brew ratio of 18g of coffee producing a 36g beverage weight.

  • You determine by tasting that the body is too low even though you’re hitting your TDS target.




18g dose






36g beverage weight at 10% TDS and 20% extraction yield




  • You also want to make the shot sweeter.

  • You decide increasing the extraction yield will be the way to do this.

  • You grind finer (or increase the temperature) and you reduce the dose to 17.5g and target 10% TDS.





17.5g dose






36g beverage weight at 10% TDS and 20.5% extraction yield





In this instance, you have navigated from 20% extraction yield up to 20.5%


In this video,