Final answer:
Adding espresso to a Dutch Frost changes its flavor, as espresso's strong taste infuses into the ice cream. In homemade ice cream making, a solution with one part salt to 11 parts water lowers the freezing point sufficiently to freeze the mixture.
Step-by-step explanation:
When a customer requests espresso in their Dutch Frost, the flavor of the ice cream changes. This is because espresso has a distinct taste, and by replacing the appropriate ounces of ice cream mix with espresso, the coffee flavor will infuse into the ice cream, altering the original flavor profile. The amount of change in flavor will depend on the proportion of espresso added in relation to the ice cream mix.
In the context of making homemade ice cream, lowering the freezing point is crucial for achieving the right consistency. Dissolving salt (NaCl) into water and adding ice creates a saltwater solution that lowers the freezing point due to the phenomenon known as freezing point depression. Since NaCl dissociates fully into ions, a solution created with one part salt to 11 parts water by mass will have a lowered freezing point, cold enough to freeze the ice cream mixture properly.