Coffee total dissolved solids

What is coffee total dissolved solids? Often abbreviated as TDS, it is a measurement of the amount of organic and inorganic material—such as sugars, acids, and oils—that has been extracted from the coffee grounds into the brewing water. It is typically expressed as a percentage of the total weight of the brewed coffee.

Why does coffee total dissolved solids matter? TDS is the primary way to measure the 'strength' of a cup of coffee. While extraction yield tells you how much of the coffee bean you have dissolved, TDS tells you how concentrated that solution is. By measuring TDS, a brewer can determine if a cup is too weak (watery) or too strong (intense), allowing for precise adjustments to the brew ratio or grind size to achieve the desired balance.

In practice, professionals use a refractometer to measure the TDS of their brew. This tool uses light refraction to determine the concentration of dissolved solids in the liquid. When combined with the weight of the dry coffee and the weight of the final brew, brewers can calculate the extraction yield, which is the gold standard for evaluating brewing efficiency and flavor development.

For the home enthusiast or professional barista, TDS provides an objective way to 'dial in' a recipe. If a coffee tastes sour or thin, a low TDS reading might suggest that the coffee is under-extracted, prompting the brewer to increase contact time or use a finer grind. If the coffee is bitter or harsh, a high TDS might indicate over-extraction, suggesting a coarser grind or a shorter brew time.

Ultimately, TDS is about consistency. It removes the guesswork from brewing, allowing roasters and baristas to replicate their favorite recipes with precision. By understanding the relationship between TDS, brew ratio, and extraction, you can move from simply making coffee to mastering the science of flavor extraction.