A Jar of Vegemite, a Window on Kraft

The recipe for Vegemite, a salty brown yeast spread famous in Australia, remained unchanged for more than 80 years. Then Irene Rosenfeld became chief executive of Kraft Foods Inc.

This summer, a milder version of Vegemite appeared on store shelves across Australia. Ms. Rosenfeld had almost nothing to do with the reformulated taste, its new packaging or its rollout -- which says a lot...