Milk became the original liquid meal. "There were fresh milk diets, people who swore they’ve never been healthier than when they ate nothing but milk," says Mendelson. By the time we retired the milkman in favor of "gable top" paper cartons from the grocery store in the 1950s, milk was deeply embedded in the American family’s regular grocery routine.
Improvements to pasteurization hastened the US milk boom post-milkman. In the 1940s, batch pasteurization was phased out in favor of a cheaper, more efficient treatment called high temperature short time method, or HTST, which "made it possible to have continuous flow systems running 24 hours a day," says Mendelson.
In the 1960s, the process evolved again, with a twist. The packaging company Tetra Pak developed a new technique, UHT, which eliminated the need for refrigeration altogether. This further slashed costs, both for distributors and consumers, as the shelf life of the product was extended almost indefinitely. Europe and other countries latched onto this new concept of unspoilable milk. Italian company Parmalat set its sights on disrupting the US milk market in the early '90s with its UHT product. Sparing no expense with its marketing efforts, Parmalat put on a free performance by Italian opera icon Luciano Pavarotti in New York's Central Park. Despite everything, the milk was a complete bust.