Advanced Coffee Making

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ACM 3.07 – The TDS Valley

The TDS Valley

The time a barista spends preparing coffee has ramifications on the productivity of a business. From start to finish, the fastest way to brew coffee to an 18–22% extraction yield is espresso. Since the end of the 1940s, espresso has been widely adopted across many different cultures, due in part to this efficiency.

Batch brew allows the preparation of anything up to 100 drinks all at the same time. These can also be efficiently prepared in around 6 minutes. Because of the commercial advantages of both these methods, other brew method styles have become less popular in the specialty coffee movement. Of these two styles, one is extremely strong, and one is extremely weak. There are a great many brew methods that lie between these two strengths — this ‘valley’ is the TDS Valley.

Coffee brewed in this valley between 2–6% TDS can be extraordinary. Long blacks or americanos at 3–3.5% TDS strength can be luscious and juicy. Diluting with less water to achieve 5% TDS can be mouth-filling and syrupy, without the often unpalatable intensity that comes with a traditional espresso. Curiously, the gap between 1.8% and 2.5% TDS is often disliked by coffee professionals. Perhaps our palates are calibrated for traditional 1.2–1.6% brews and the beverage has to be significantly stronger before our palates recognise it as something other than ‘a drip/filter coffee that’s too strong’.

With your help, we are drafting the CCCC to illuminate this region of strength and to show you common brew ratios for all the brew methods traversing this TDS valley.

**This research is ongoing. We will publish our findings once we have had enough responses to see some distinct trends. Could you spend 5 minutes filling out this survey to help us?**

Drawing Margins for Brew Methods in the TDS Valley

You recall the lesson called Operate Away from the Margins earlier in this chapter? When we draw our lines to create the brew-ratios on the CCCC we needed to set a lower margin and an upper margin for brew-ratios in each category of brew method.