The Lingering Heat over Pasteurized Milk

milk bottles

Filling milk bottles, Briarcliff Farms, New York

Spurred by nationalistic pride after the defeat of French troops in the Franco-Prussian War of 1870, Pasteur applied his new technique to the creation of a “beer of revenge” that would top Germany’s finest. In one demonstration he collected beer from Paris’s best cafes and treated some to pasteurization. The treated ones kept indefinitely, while the remainder soon became cloudy and undrinkable. Pasteur shared his knowledge with French breweries to shore up their business prospects, though the best “beer of revenge” was arguably brewed in Copenhagen’s Carlsberg brewery. Benefiting enormously from Pasteur’s heating and yeast-propagation techniques, the Carlsberg brewery commissioned a marble bust to celebrate its new hero.

Germany could take its own measure of satisfaction when agricultural chemist Franz von Soxhlet first suggested using pasteurization for bottled milk in 1886. Soxhlet, a prodigious chemist himself, had already studied the physiological chemistry of milk and devised a new method for extracting and analyzing fat from milk solids, leading to the popular Soxhlet extractor. The chemist’s research also illuminated some key differences between human and cow’s milk and yielded the first description of lactose, as well as the first separation of milk’s major protein constituents.

Germany’s next contribution to the pasteurization movement came in the form of a young doctor named Abraham Jacobi. Later known as the father of American pediatrics, Jacobi left Berlin for New York after being jailed two years for high treason during the political turmoil of the early 1850s. An early advocate of birth control and a socialist who corresponded with Karl Marx, Jacobi fought the notion that raw milk was safe for infants and took up the challenge of convincing a skeptical public that heating milk until bubbles appeared would save lives.

If Jacobi is often credited with bringing pasteurization to the United States, a close friend and fellow German émigré named Nathan Straus was arguably its biggest booster. In 1892 the New York City businessman and philanthropist opened the Nathan Straus Pasteurized Milk Laboratory and soon introduced the first low-cost milk depots for the city’s poor.

And that’s when the controversy really began. By then milk was known to be a fertile medium for a growing menagerie of microbes, or “minute plants,” as some called them. The microbes, in turn, were commonly associated with typhoid and scarlet fevers, diphtheria, and devastating intestinal diseases collectively known as “cholera infantum.” In 1891 the infant mortality rate for New York City averaged 240 deaths per every 1,000 births. Many of those deaths were believed to be due to tainted milk supplies.

Raw milk was also widely blamed for contributing to the “white plague” of tuberculosis, which passed easily from humans to cows and back again. Even finance giant J. P. Morgan had to slaughter a third of his pedigreed herd after a tuberculosis outbreak, despite a doctor’s affirmation that Morgan’s was the “best example in the country of a scrupulously clean, sanitary farm.”

The same could not be said for many other producers. Barns were frequently filthy, and some cows were fed swill left over from whiskey distillation. An 1895 study found that more than one-fourth of 165 herds examined in 17 states harbored tuberculosis. Many distributors were no better. Ten percent of the milk examined by Philadelphia’s milk inspector during July and August of 1891 was condemned because it had been adulterated by some additive or diluted with water.

Meanwhile, confusion reigned over what pasteurization entailed, with some suggesting counterproductive heat treatments of only 130 degrees Fahrenheit for ten minutes. Others suggested 150, 155, 160, or 167 degrees, all dutifully defined as pasteurization. At the other extreme a Medical News article from 1892 reported on the “disheartening” results of feeding sterilized milk to infants at Philadelphia Hospital. Seriously ill children initially recovered. “But later on, most serious and baffling disorders supervened. The children who at first had fattened and thriven on sterilized milk became emaciated and anemic; grave intestinal disorders, which resisted every form of medication and treatment, appeared, and finally, these sterilized-milk-fed children perished of non-nutrition.”

A separate report from the Dairy Commissioner from the State of New Jersey suggested a biochemical explanation. The prolonged boiling of milk, two researchers found, converted soluble albumin to an insoluble, semi-curdlike form not easily digested. Philadelphia Hospital promptly began pasteurizing its milk at 155 degrees Fahrenheit.

By the turn of the century some researchers were concluding that pasteurization at 140 degrees Fahrenheit for 30 minutes or above 149 degrees for 20 minutes was sufficient to deactivate “tuberculous milk.” Loton Horton, president of the Sheffield Farms Company, remained unconvinced and set up his own experiments at one of the seven pasteurizing plants he operated around New York City. After experimenting with time, temperature, and pathogenic tests on guinea pigs, Horton settled on treating his own bottled milk at 146 degrees for 30 minutes, followed by a rapid cooling to 40 degrees.