What is the maximum entry proof allowed for bourbon?

The maximum entry proof allowed for bourbon is 125. This means that when the distiller adds water to the distilled spirits before they enter the barrel for aging, the proof of the liquid must not exceed 125. This regulation is established to ensure that the aging process in the barrel can effectively impart flavors and aromas to the whiskey while maintaining the characteristics that define bourbon. By keeping the entry proof at or below this level, distillers can optimize the interaction between the spirit and the wood of the barrel, which is crucial for developing the rich flavors associated with bourbon.