How we test
Our tester blends each food with an equal weight of deionised water, then measures the pH and acid reserves (as the volume of base [0.1M sodium hydroxide] required to adjust the pH to 7.0). Familiar to swimming pool owners, pH is a scale of acidity and alkalinity. Strong acids have a pH of 0; strong bases 14. Foods or drinks with a pH below 5.5 can cause erosion of the dental enamel.
Cordials are diluted with water following the instructions on the label, while other drinks are tested without adding water; for carbonated drinks, the pH is measured immediately after opening and again after the drink has gone flat. Values for sugar content are taken from the nutrition information on the label.