A Pioneer in Thermal Death-Time Standards

Also contributing to the scientists’ advances were materials improvements made by industry. “You need to almost start in the early 1900s, when corporations made better tin plate so you had stronger containers, and rolled seams were improved so you had better quality,” said Dr. Pflug.

Bigelow was a professor of chemistry at Oregon State College who had also served as chief chemist and then director of the research laboratories of the National Canners Association. In his article, “Problems of Canning Operations,” published in the American Journal of Public Health in March 1918, Bigelow described heat and pH and their effect on bacteria. “The temperature necessary for sterilization varies through wide limits according to the nature of the product,” he wrote. “For the destruction of microorganisms, it is well known that a higher temperature is necessary for the spore form [of bacteria] than for the vegetative form. Again, the higher the acidity (within the range of the acidity of foods, for instance), the lower the temperature required for sterilizing the food.

“In general, spore-forming bacteria do not thrive as well in the more strongly acid foods as in foods of very low acidity. For both of these reasons the more strongly acid foods, such as tomatoes and the majority of fruits, can be sterilized at a lower temperature or in shorter time than foods of lower acidity.”

In the early 1920s, Bigelow, along with Drs. Esty and Meyer, researched heat-resistant bacteria. Drs. Esty and Meyer had been trying to better understand the organism Clostridium botulinum, because there had been several outbreaks and poisonings caused by that bacterium in canned foods that had been made in California. At the time, according to an article written in the University of California library publication Calisphere after his death, Dr. Esty was at the Hooper Foundation for Medical Research, University of California. The three men “helped to establish the methods and fundamental values in heat resistance of spoilage bacteria that form the basis of present-day scientific processing of canned foods,” according to Calisphere, which also noted, “Dr. Esty’s loss will be felt strongly by not only the West Coast members of the National Canners Association, but by the entire industry, for the contributions of his entire career had been of national import in the advancement of canning technology. His personal integrity had won for him the complete respect and confidence of canners, government officials, and fellow food scientists.”

Dr. Esty was born in Slatersville, R.I., in March 1893 and received his bachelor’s in chemical engineering from Rhode Island State College in 1914. He changed his major to bacteriology for his graduate work and earned a master’s and a PhD from Brown University in 1915 and 1918, respectively. He taught bacteriology at Brown from 1914-1916 and began working at the National Canners Association in January 1919 as a bacteriologist, developing a technique to determine the heat resistance of bacterial spores. He also conducted field studies to determine their source and made experimental packs inoculated with spore suspensions to determine sterilization time for various canned foods. His collaborations with Meyer and Bigelow, then director of research at the National Canners Association, resulted in pH and microbiological studies that affect canning processes today.

Valigra is a freelance writer based in Cambridge, Mass. Reach her at [email protected].