Red winter wheat is Maker's Mark "secret" ingredient, it's really no secret but it makes the difference in their recipe. This grain is hardy and very heavy. If you were to hold two jars of the same volume, one containing red winter wheat and the other barley, the wheat jar would be significantly heavier. This particular variety of wheat adds the soft, sweet flavor that is a signature of this bourbon, but it also makes the cooking process more challenging. The majority of the time whiskey distillers will pressure cook the grain before fermenting because it's easy and economical but wheat cannot be cooked under pressure, instead it needs to be handled gently. Bill Samuels Sr. realized this and had to work out the process of cooking his choice of grains.
- Corn is added to a soup stock of clean limestone filtered water and left over distillers beer in large white cooking tanks and is heated up to no more than 212 degrees.
- A cooling process is started after that and once the brew reaches 160 degrees the red winter wheat is added.
- As the cooling continues the final grain, barley, is added and the mix is allowed to cool naturally overnight.