A food preparation appliance has a base, a blade member rotatable in a direction of rotation, and a container with a closed bottom, an open top and a tubular sidewall together defining an interior space of the container. The top of the container is configured for releasable connection with the base, with the blade member disposed within the interior space of the container. The sidewall has a rib projecting inward of the interior space of the container and extending lengthwise along at least a portion of the sidewall from the top of the container toward the bottom of the container. The rib has, in the direction of rotation of the blade member, a peak defined as the shortest transverse dimension measured from the center of the container to the sidewall at a respective height along the portion of the sidewall having the rib, the rib being asymmetric in transverse cross-section.