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What Are Coffee Solids?

When you visit specialty coffee forums, you are likely to find lengthy discussions on coffee solids and extraction percentages. You may fail to understand what coffee solids mean. Coffee solids are also known as total dissolved solids (TDS). TDS is a highly controversial topic. Some coffee enthusiasts argue that TDS is a game changer while others believe it is a useless distraction. But what are coffee solids? What levels are appropriate? Are coffee solids useful? Read on for detailed answers to these questions.

coffee solids

Coffee Solids Defined

Coffee solids or TDS refers to the amount of coffee dissolved in a certain volume of water. It is measured in milligrams per liter (mg/L) or parts per million (ppm). For instance, a liter of water contains 1000 g of dissolved solids, which is equivalent to 1,000,000 mg/L of water.

However, it is worth noting that measurements for total dissolved solids are not exactly what is dissolved but the amount of the substance dissolved. For instance, 100 mg/L of sugar has a similar TDS as 100 mg/L of coffee.


What are Coffee Solids?

When brewing coffee, you are extracting some coffee compounds into the brewing water. The extracted compounds that dissolve in the brewing water gives coffee its delicious taste and aroma. The amount of coffee solids differs but ranges from 1 to 2 percent.

But what are these coffee solids that dissolve in water? Coffee solids include caffeine, esters, chlorogenic acids, and acids such as lactic acid, citric acid, and malic acid. These solids give coffee its body, flavor, and aroma. These are the solids taken into account when taking TDS measurements in coffee. Without these compounds dissolving, your coffee would be tasteless.

The amount of coffee solids that dissolve in water when brewing can be altered to control how the final brew tastes. For instance, you can alter the brewing time, coffee brewing method, brewing temperature, and grind size to give your coffee a different taste.


Why Do Coffee Solids Matter?

Since coffee solids relate to the amount of coffee compounds dissolved in the brewing water, you can use TDS to determine the strength of your brew. However, you should limit the amount of coffee solids that get into the brew.

If you exceed the limit, less desirable compounds will dissolve into your brewing water. As a result, you will get an over-extracted brew that tastes bitter. For instance, if you exceed the brewing time, temperature, or use the wrong grind size for a certain brewing method, there will be over-extraction.


Does the Water Quality Affect Coffee Solids?

If you can remember science lessons on diffusion, you are aware that compounds travel from an area of high concentration to an area of low concentration. That is exactly how coffee works during brewing. The amount of coffee compounds in the brewing water correlates to the efficiency of extraction. For instance, water with low mineral content over-extracts coffee whereas water with high mineral content under-extracts.

Brewing water contains dissolved solids such as magnesium, chlorides, and calcium. When brewing, you can control their concentration through water filtration techniques such as re-mineralization and reverse osmosis. Water filtration ensures that the water has consistent dissolved solids for the best extraction.


How to Control Coffee Solids in Your Cup

There are several methods used in controlling coffee solids. One of the ways you can control coffee solids is to use different brew methods and roast profiles. For instance, darker roasts allow for more soluble compounds while lighter roasts allow for fewer soluble compounds.

With that said, finer grinds of darker roast are best for shorter extraction times to extract soluble compounds within a short time. On the other hand, a medium-coarse grind comprising lighter roasts is suitable for longer brewing times to extract enough soluble compounds.

You can also control coffee solids by altering the water quality and brew ratios. Brew ratios are necessary since they assist in balancing coffee extraction and the amount of soluble compounds extracted. The quality of water is also necessary since there are minerals present in the brewing water.

The importance of water quality is that the soluble minerals present affect extraction. For instance, harder water has more minerals, which causes over-extraction. On the other hand, softer water has lower mineral content which leads to less extraction.



Brewing a perfect cup of coffee is often challenging. Before you perfect brewing coffee like a barista, you may face inconsistencies with your final brew. The reason may be due to coffee solids. So what are coffee solids? They are the amount of soluble coffee compounds that end up in your brew upon extraction. By knowing what coffee solids are and how to control them, you are one step closer to brewing a balanced cup of coffee with consistency.