ST. PAUL — State health officials say green whole head cabbage was the likely source of E. coli that sickened 15 people in Minnesota in July.

The Minnesota Department of Health said Friday the cabbage likely was contaminated before it was distributed to restaurants.

Investigators were able to interview 14 of the cases. Thirteen of them ate at nine different Applebee’s restaurants in Minnesota and one ate at a Yard House restaurant.

Many of those interviewed reported eating the Oriental chicken salad at Applebee’s. That led Applebee’s to temporarily pull the menu item from its Minnesota restaurants. The salad returned to the menu after Applebee’s got different sources for the ingredients.

Minnesota officials traced the cabbage to a supplier outside of Minnesota and are working with federal investigators to identify the source.