Cold brew coffee takes about 12 hours to brew. the slower brewing process pulls the coffee flavor and caffeine from the coffee grounds, but most of the compounds that make drip brew coffee taste bitter and sour do not dissolve into the water. which physical property of coffee is responsible for this difference in flavor?

Solubility.

Explanation:

Brew coffee is nothing but coffee made by pouring hot water on ground coffee beans. It can have various taste depending upon how it is brewed. Its various types can be drip brewed coffee, filtered coffee, etc.

Different brewed coffee tastes different because of their difference in solubility. The the degree of  solubility of coffee in water changes its tastes.