Dr. Mary MacArthur was the first woman to be named as Fellow of the Agricultural Institute of Canada for her contributions to Canadian agriculture. She became well known for her scientific leadership on successful food dehydration and freezing in the 1940s. Her contributions included fundamental research on methods for determining the inactivation of enzymes in plant tissues prior to dehydration. She had a large dehydration tunnel built at the Central Experimental Farm in Ottawa, Ontario in 1942, in which several thousand experiments were carried out.
Dr. MacArthur is credited with identifying that vegetables needed blanching to inactivate enzymes before dehydration. She worked with scientists at Kentville, Nova Scotia who provided her with the dehydrated vegetables for further analysis in Ottawa. This was an important activity during the war years as many fruits and vegetables had to be dehydrated and shipped to Europe for the war effort. Before the end of the Second World War, she also published a paper on freezing commercially packaged asparagus, strawberries and corn.
As a result of her work, the appearance and nutritional value of commercial dehydrated cabbages, carrots, potatoes, and turnips improved markedly and paved the way for future improvement in the field of dehydrated and frozen foods.