Natural pH Indicators and their Sensitivities to pH

Abstract

Anthocyanins are a class of colorful compounds typically found in plant foods and are widely used for their color in the food industry. They tend to appear red, purple, blue, or black. Given anthocyanins’ ability to fluctuate in their color properties, this instability has also been applied for use as a pH indicator in the food industry. This study analyzes the sensitivities of various anthocyanin-containing foods as pH indicators, as assessed by their color changing property and deviance in color between solutions with a pH difference of 0.5. Solutions of blackberries, black grapes, raspberries, blueberries, red cabbage and plums were derived, and reacted with household low-pigmented test ingredients ranging from a pH of 2 to 9. Pigmented aqueous solutions of red cabbage, blackberries, blueberries, plums, black grapes and raspberries showed a significant color difference between all pairs of test  ingredients with a pH difference of 0.5.