Why freezers, microwaves didn’t kill E. coli in Pillsbury Pizza Pops

A package of Pepperoni and Bacon Pillsbury Pizza Pops are shown in this undated handout photo from the Canadian Food Inspection Agency. THE CANADIAN PRESS/Handout - Canadian Food Inspection Agency (Mandatory Credit)

TORONTO — Freezing or microwaving food does not reliably kill E. coli, a bacteria that has spurred an outbreak and recall of several Pillsbury brand Pizza Pops in Canada.

A public health notice Monday stated 20 people got sick and four have been hospitalized between early October and late November after eating or handling certain pepperoni and bacon Pizza Pops.

Lawrence Goodridge, a professor and Canada Research Chair in foodborne pathogen dynamics at the University of Guelph, says freezers stop the growth of bacteria, but they don’t kill it.

That means if the product got cross-contaminated or there was a sanitation failure when it was made, the freezer would actually preserve the bacteria.

Goodridge says the reason heat also didn’t kill E. coli in this case is because microwaves don’t heat food equally and leave patches of cold spots where the bacteria can survive.

Microwaves vary and their power weakens over time, which means putting a Pizza Pop in on High for one minute is different for each person.

This report by The Canadian Press was first published Dec. 23, 2025.

Canadian Press health coverage receives support through a partnership with the Canadian Medical Association. CP is solely responsible for this content.

Hannah Alberga, The Canadian Press