Which factor determines the proper grind of coffee?

The brew method is indeed the key factor that determines the proper grind of coffee. Different brewing techniques require different grind sizes to optimize extraction and flavor. For example, a French press requires a coarse grind to prevent the coffee from becoming too bitter and to ensure proper steeping, while espresso shots need a fine grind for quick extraction under pressure.

The grind size influences the surface area of the coffee beans in contact with water, thus impacting how quickly flavors are extracted. If the grind is too large for a particular brewing method, the resulting coffee may be weak or under-extracted, lacking in flavor. Conversely, if the grind is too fine for a brewing method like a drip coffee maker, it may lead to over-extraction and a bitter taste. Therefore, understanding the specific requirements of the brew method is essential for achieving the desired flavor profile.

While other factors such as the type of coffee bean, the store manager's preferences, or customer desires can influence the overall coffee experience, they do not directly dictate the necessity of grind size adjustments as the brew method does.