Joseph Hotchkiss developed the carbon dioxide injection method to extend the shelf life of dairy products.

Thanks to a Cornell-based technique of injecting antimicrobial carbon dioxide into the cheese curds’ dressing, today, a container of cottage cheese from the grocery store lasts two or more months (unopened) in the home refrigerator. Food Scientist Joseph Hotchkiss gets the credit for the CO₂ injection method—an inexpensive and healthful way of “pasteurizing” dairy products without the heat that changes flavors. But he wasn’t the first, Hotchkiss readily acknowledges. A hundred years ago, in 1907, Cornell agricultural scientists mixed raw (unprocessed) milk with carbon dioxide, left the milk at room temperature, and reported: “After three days the milk had a sweet and pleasant taste.”

The man who earned a place in dairy foodsprocessing history (Hotchkiss has been called the “Guru of Active Packaging”) knows the story behind CO₂. Earlier in his career, as a chemist for a major American brewer, Hotchkiss learned a thing or two about carbon dioxide.

Cottage cheese, a major outlet for the American dairy industry and a source of disappointment for shoppers, turned out to be an apt application for CO₂ preservation. The Hotchkiss-Cornell process injects pressurized CO₂ in carefully calculated levels—too much and the cottage cheese would be suspiciously fizzy; too little CO₂ and the process loses its antimicrobial effect—through cold tubing, then encloses the cottage cheese in gas-impermeable packaging.

Before CO₂ pasteurization became the industry standard, a container of cottage cheese was marked with a shelflife of about 21 days, ”but it was barely edible for the last seven or eight,” Hotchkiss recalls. Nowadays, cottage cheese is marked for an 85- to 90-day shelf life. Hotchkiss and his students open containers after 120 days, “and it’s just as good as it could be.” (Roger Segelken)