Why we use phenalphalein is indicator for acidity test for milk?

Phenolphthalein is used as an indicator for acidity tests in milk because it changes color in response to pH variations, specifically transitioning from colorless in acidic conditions (pH below 8.2) to pink in alkaline conditions (pH above 8.2). Since milk can become acidic due to spoilage or bacterial activity, observing the color change with phenolphthalein helps determine the acidity level. Its clear visual transition makes it an effective tool for assessing milk freshness and quality.