Oreology— “Milk’s Favorite Cookie”

Synopsis

Despite their seemingly simple structure, sandwich cookies like Oreos exhibit complex mechanical behaviors during and as a result of separation. A recent study investigated the fracture behavior of the creme filling when Oreos are twisted apart using a laboratory rheometer. The findings reveal that creme distribution upon separation is primarily influenced by the preexisting adhesion between the creme and the wafers, rather than rotation rate, creme height, or flavor. Failure direction—whether the creme stays on one wafer or splits between both—can be predicted with up to 80% accuracy based on the cookie's position within the package. These findings suggest that external conditions, such as temperature or mechanical forces during packaging, may affect the outcome. In my presentation, I will discuss the implications of these results for understanding the rheology of sandwich cookies and how this knowledge may apply to other torsional processes in everyday life.

Reference: C. E. Owens et al., Physics of Fluids 34, (2022).