The Chemistry of Water in Coffee

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    A Scientific Study of the Chemistry of Water in Coffee

    Great tasting coffee needs calcium, barium and magnesium to bond with the flavor molecules that are in coffee grounds, and a water softener will remove these necessary metallic ions from the brew. Water softeners cause the ions to be exchanged with sodium, and this will completely change the flavor of the coffee (and not for the better).

    water in coffee

    Water contains magnesium and calcium, while coffee is naturally rich in minerals and an estimated 700 aromatic compounds. There is also “hard” water, which is rich in magnesium, and “soft” water, which is high in sodium. A water softener is typically used to remove excess mineral content from the water source in order to make it more friendly to product like dish soap, laundry soap, or shampoo.

    Since the mineral content of the water is what affects the flavor of coffee, Christopher Hendon, a noted chemist from the University of Bath, decided to conduct a study. His study focuses on how different types of water can affect the chemical extraction and the 6 or more chemicals that help to determine the coffee’s flavor.

    Mr. Hendon carefully studied the relationship between the quality of water and the quality of the coffee. He used specific parameters of roasted coffee beans to create variations in the taste of coffee while maintaining the beverage’s high standards. He discovered that when the magnesium commonly found in hard water stuck to eugenol (one of the chemical compounds found in coffee) the beverage had a rich and extremely pleasant taste. He also discovered that when a water softener was used prior to brewing, the levels of sodium significantly increased in the final cup. It seems that when there are high levels of magnesium present, the process of extracting flavor from the coffee grounds is improved, while the opposite is true when bicarbonate levels are increased.

    Magnesium and Calcium

    These metals dissolve as charged particles when submerged in water, and are found on the periodic table as Mg+2 and Ca+2. This positive charge is crucial for overall flavor, since most of the compounds in coffee are negatively charged. This means that the negative flavor compounds will attract the positively charged ions, effectively eliminating any bitter and unpleasant tastes. If you are wondering what “hard water” is, it simply means that it contains increased levels of magnesium and calcium.

    Magnesium Ions, Calcium, and Sodium All Help in Flavor Extraction

    When there are magnesium ions present in the water, it helps to extract fruity, sharp flavors, while creamy notes are highlighted by the presence of calcium. This metallic ion also acts as a type of buffer and prevents acidic notes from flavoring the brew.

    When it comes to these ions’ effect on extraction, magnesium has the greatest effect, followed by calcium and then sodium. Even though the magnitude of their effects varies, the overall balance at the end is basically the same.

    This means that to get the best flavor from the coffee grounds you will want to use magnesium-rich water. It is also just as important to find the correct balance between the magnesium, calcium, and sodium ions. According to the study you actually need all three ions to get the best flavored beverage.


    water and coffee When it comes to keeping the acidity level in the coffee balanced, you need to have the right amount of a carbonate compound. When there is the perfect amount of carbonate, the acid levels are balanced so the beverage does not have a bitter taste. If the carbonate compound levels are too high, the acid that it absorbed will be released into the coffee again. While carbonate at low levels is necessary for the best tasting coffee, it can also cause problems with your brewing equipment if the water has a high concentration of calcium. When exposed to heat, calcium carbonate can form. This can clog and damage even the best coffee brewing machine.

    Brewing a great tasting cup of coffee is an art and a science. While many people believe that their method of extraction is the best, the type of water they use is just as important as the method itself.

    Thank you for reading.

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