TDS? Tasteful Drink Selection?

You’ll hear many coffee aficionados talking about the TDS of their brewing water when preparing coffee or TDS of their final brewed coffee (more on the later in a future post).  

For those unfamiliar, Total Dissolved Solids (TDS) is the measure of the combined content of all organic and inorganic substances in water, including minerals, salts, and other dissolved compounds.  The take-away here is that TDS only measures the concentration of dissolved solids, not their composition. TDS also doesn’t account for water pH, which is a critical factor in extraction efficiency his essentially means that you could have water with a TDS within recommended range, however the composition of minerals that negatively affect the coffee brewing could easily outweigh the ideal minerals.

So, it’s important to appreciate that TDS is just one aspect of water quality that can affect coffee brewing. To truly understand the impact of water on coffee, you should also consider mineral composition.

The mineral composition of water affects both the extraction process and the final taste of the beverage. The key minerals present in water that impact coffee brewing include calcium, magnesium, and bicarbonate.

Impact on the extraction process:

When brewing coffee, hot water dissolves and extracts compounds from the coffee grounds, creating the final product we consume. The extraction process is significantly affected by the mineral content in the water. Water containing high levels of minerals, specifically calcium and magnesium, is classified as “hard” water, while water with low mineral content is “soft” water.

Calcium and magnesium ions present in water can create complexes with compounds found in coffee, thereby improving the extraction of flavors. Magnesium ions, in general, are more efficient at extracting flavor compounds compared to calcium ions.

Influence on flavor profile:

The mineral content in water directly affects the taste of the coffee. Varying minerals can either emphasize or suppress specific flavor notes in the coffee:

Calcium: Calcium ions can enhance the perception of creaminess and body in coffee, but too much calcium may result in a chalky or flat taste.

Magnesium: Magnesium ions can improve the extraction of fruity and acidic notes in coffee, contributing to the overall flavor balance. However, excessive magnesium might result in an overly sharp or bitter taste.

Bicarbonate: Bicarbonate ions can neutralize the acidity in coffee, which can lead to a less vibrant, flatter flavor profile. Elevated levels of bicarbonate can also lead to the formation of precipitates with coffee compounds, resulting in a cloudy appearance and a chalky mouthfeel.

Impact on coffee brewing equipment:

The mineral content in water can also have an effect on the coffee brewing equipment, particularly when using hard water. Calcium and magnesium can form scale deposits on the brewing equipment, which can reduce its efficiency and potentially impact the taste of the coffee. Regular descaling and maintenance are essential to address these issues.

While it’s not particularly easy to accurately monitor mineral compositions without having samples collected by a lab, it is important to note that appropriate balance of minerals and alkalinity can enhance flavor extraction and provide a well-rounded taste, while an imbalance can result in off-flavors and problems with brewing equipment.