The pH indicator for solid food called PHIND is a detector that reveals the acidity of solid food. Because the acidity of human stomach is about pH 3 and because the possibilities of the body to neutralize excesses of acidity are limited, the sole fact of eating acidic food can cause discomfort or heartburns. The PHIND is specifically humidified to turn red as soon as it is on contact with an acidic food even if this acidic food is solid, warning people of the danger of discomfort or heartburns. Sealed in a watertight and chemically neutral envelope to keep its properties in all circumstances, the PHIND is always ready to reveal the acidity of solid food. The PHIND is effective, easy to use and disposable.