08 January 2009

ph meters by Steffi Holt

Most of us will have heard the term pH, and maybe some of us know that it relates to acidity, but fewer of us will have thought about how this can affect the flavour of a drink we are making.
So how does pH work? Explained simply, it is the concentration of Hydrogen (H+) ions within a solution compared to pure water (H2O). At room temperature, some water molecules split into their ionic (charged) components – H+ (positively charged) and OH- (Oxygen joined to a Hydrogen with an overall negative charge).
Ionic charges work in the same way as magnets and opposites attract, so the amount of molecules that this happens to in pure water is relatively low – only 1 in 555million water molecules stays separated in this way, and as there is nothing else in the solution for the ions to bind to, the number of H+ equals the number of OH-. This gives pure water a pH of 7, and other solutions are compared to this. When the water is impure (has things mixed into it) the ionic balance is disrupted – either the OH- or the H+’s will bind to the molecules within the solution and leave an excess of the other. Due to the nature of the calculation giving us pH, as the concentration of H+ increases, the pH decreases, so the more acidic a solution, the lower the pH.
How can we as bartenders use this knowledge to improve our drinks? One of the main features of a good drink is balance – bartenders must learn to appreciate balance in drinks so that even if a drink is not to their liking, it can be recommended to someone else who may like it. Acidity and therefore pH play an important role in the balance of drinks.
We can easily measure pH of drinks & ingredients using a pH meter. They are available in versions that are portable, small, waterproof & very cheap, so the average bar can easily use them for many things. For example – citrus juices vary with seasons & countries of origin. This can make drinks too sour/sweet depending on your source. It is simple to test the juice before use (as long as you don’t squeeze as you go!) in order to compensate for any variety in pH & ensure drinks standards are maintained.
Below is a table showing some average pHs…

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