After my post V60: Drip or Immersion on VST Coffee Tools? questioning which settings to use on the VST App, I thought i’d take it one step further and develop a calculator that would allow users to work out the settings for their particular brew method.
You can find the calculator here. This calculator works for Pour Overs, Clever Drippers, Aeropress and Batch Brewers. It allows you to pop in the particulars of your brew and it will spit out an Adjusted LRR that will give you the most accurate EXT %.
All you need to do is prepare a brew using your technique and measure the following:
Dose (g) – Mass of the dry grounds in grams.
Brew Water Weight (g) – The weight of the water you are starting with. This calculator is assuming its at 90+ degrees, similar to the app.
TDS of the last 10g (%) – as you get to the end of your brew, capture the last 10g or so to come through and take a measurement using the Refractometer. Also measure the weight of the pulled sample to add to Beverage Weight
Beverage Weight (g) – The weight of the final beverage. Combination of the cup and the sample pulled for the TDS of the Last 10g
From these numbers the calculator will work out the Actual Liquid Retained Ratio (LRR), and also the Adjusted LRR. This Adjusted LRR is then placed into the app. When you place this Adjusted LRR into the app it will give you an Extraction Yield % that is now accurately taking into account the extracted coffee that still remains in the coffee bed. Both MOIST and CO2 should be returned to Zero, in my view if you can’t measure it you may as well leave it at Zero.
Feel free to shoot across any questions.