Most people have never heard of Mary Engle Pennington, yet her work changed how America eats. Born in 1872, she was a scientist who refused to accept the poor food standards of her time. When spoiled milk and contaminated eggs were common, she fought to make them safe. Mary was one of the first women to earn a PhD in science from the University of Pennsylvania. Her research focused on bacteriology and food preservation, leading her to develop the cold storage systems that became the backbone of