It has a pH of approximately 7.4, leaving it with a bright pink or red appearance due to the indicator phenol red. Sugar fermentation lowers the pH and the phenol red indicator registers this by changing to yellow.
With a pH of roughly 7.4, the substance displays a bright pink or red coloration because of the indicator phenol red. When sugar fermentation takes place, it modifies the pH, leading to a shift in color from pink/red to yellow through the use of the phenol red indicator.