Tuesday April 20, 2021’s Smile of the Day: Pasteurization
On this Day:
In 1862, the first pasteurization test was completed by Frenchmen Louis Pasteur and Claude Bernard. Well, while this led to a revolution in how foods were treated and ultimately saved countless lives, this wasn’t the first attempt at preserving food through the application of heat.
Pasteurization or pasteurisation is a process in which packaged and non-packaged foods (such as milk and fruit juice) are treated with mild heat, usually to less than 100 °C (212 °F), to eliminate pathogens and extend shelf life. The process is intended to destroy or deactivate organisms and enzymes that contribute to spoilage or risk of disease, including vegetative bacteria, but not bacterial spores.
The process was named after the French microbiologist, Louis Pasteur, whose research in the 1860s demonstrated that thermal processing would deactivate unwanted microorganisms in wine. Spoilage enzymes are also inactivated during pasteurization. Today, pasteurization is used widely in the dairy industry and other food processing industries to achieve food preservation and food safety.
By the year 1999, most liquid products were heat treated in a continuous system where heat can be applied using a plate heat exchanger or the direct or indirect use of hot water and steam. Due to the mild heat, there are minor changes to the nutritional quality and sensory characteristics of the treated foods. Pascalization or high pressure processing (HPP) and pulsed electric field (PEF) are non-thermal processes that are also used to pasteurize foods.
The process of heating wine for preservation purposes has been known in China since AD 1117, and was documented in Japan in the diary Tamonin-nikki, written by a series of monks between 1478 and 1618.
Much later, in 1768, research performed by Italian priest and scientist Lazzaro Spallanzani proved a product could be made “sterile” after thermal processing. Spallanzani boiled meat broth for one hour, sealed the container immediately after boiling, and noticed that the broth did not spoil and was free from microorganisms. In 1795, a Parisian chef and confectioner named Nicolas Appert began experimenting with ways to preserve foodstuffs, succeeding with soups, vegetables, juices, dairy products, jellies, jams, and syrups. He placed the food in glass jars, sealed them with cork and sealing wax and placed them in boiling water. In that same year, the French military offered a cash prize of 12,000 francs for a new method to preserve food. After some 14 or 15 years of experimenting, Appert submitted his invention and won the prize in January 1810. Later that year, Appert published L’Art de conserver les substances animales et végétales (or The Art of Preserving Animal and Vegetable Substances). This was the first cookbook of its kind on modern food preservation methods.
La Maison Appert (English: The House of Appert), in the town of Massy, near Paris, became the first food-bottling factory in the world, preserving a variety of foods in sealed bottles. Appert’s method was to fill thick, large-mouthed glass bottles with produce of every description, ranging from beef and fowl to eggs, milk and prepared dishes. He left air space at the top of the bottle, and the cork would then be sealed firmly in the jar by using a vise. The bottle was then wrapped in canvas to protect it while it was dunked into boiling water and then boiled for as much time as Appert deemed appropriate for cooking the contents thoroughly. Appert patented his method, sometimes called appertisation in his honor.
Appert’s method was so simple and workable that it quickly became widespread. In 1810, British inventor and merchant Peter Durand, also of French origin, patented his own method, but this time in a tin can, creating the modern-day process of canning foods. In 1812, Englishmen Bryan Donkin and John Hall purchased both patents and began producing preserves. Just a decade later, Appert’s method of canning had made its way to America. Tin can production was not common until the beginning of the 20th century, partly because a hammer and chisel were needed to open cans until the invention of a can opener by Robert Yeates in 1855.
A less aggressive method was developed by French chemist Louis Pasteur during an 1864 summer holiday in Arbois. To remedy the frequent acidity of the local aged wines, he found out experimentally that it is sufficient to heat a young wine to only about 50–60 °C (122–140 °F) for a short time to kill the microbes, and that the wine could subsequently be aged without sacrificing the final quality. In honour of Pasteur, this process is known as “pasteurization”. Pasteurization was originally used as a way of preventing wine and beer from souring, and it would be many years before milk was pasteurized. In the United States in the 1870s, before milk was regulated, it was common for milk to contain substances intended to mask spoilage.
Milk is an excellent medium for microbial growth, and when it is stored at ambient temperature bacteria and other pathogens soon proliferate. The US Centers for Disease Control (CDC) says improperly handled raw milk is responsible for nearly three times more hospitalizations than any other food-borne disease source, making it one of the world’s most dangerous food products. Diseases prevented by pasteurization can include tuberculosis, brucellosis, diphtheria, scarlet fever, and Q-fever; it also kills the harmful bacteria Salmonella, Listeria, Yersinia, Campylobacter, Staphylococcus aureus, and Escherichia coli O157:H7, among others.
Prior to industrialization, dairy cows were kept in urban areas to limit the time between milk production and consumption, hence the risk of disease transmission via raw milk was reduced. As urban densities increased and supply chains lengthened to the distance from country to city, raw milk (often days old) became recognized as a source of disease. For example, between 1912 and 1937, some 65,000 people died of tuberculosis contracted from consuming milk in England and Wales alone. Because tuberculosis has a long incubation period in humans, it was difficult to link unpasteurized milk consumption with the disease. In 1892, chemist Ernst Lederle experimentally inoculated milk from tuberculosis-diseased cows into guinea pigs, which caused them to develop the disease. In 1910, Lederle, then in the role of Commissioner of Health, introduced mandatory pasteurization of milk in New York City.
Developed countries adopted milk pasteurization to prevent such disease and loss of life, and as a result milk is now considered a safer food. A traditional form of pasteurization by scalding and straining of cream to increase the keeping qualities of butter was practiced in Great Britain in the 18th century and was introduced to Boston in the British Colonies by 1773, although it was not widely practiced in the United States for the next 20 years. Pasteurization of milk was suggested by Franz von Soxhlet in 1886. In the early 20th century, Milton Joseph Rosenau established the standards – i.e. low-temperature, slow heating at 60 °C (140 °F) for 20 minutes – for the pasteurization of milk while at the United States Marine Hospital Service, notably in his publication of The Milk Question (1912). States in the U.S. soon began enacting mandatory dairy pasteurization laws, with the first in 1947, and in 1973 the U.S. federal government required pasteurization of milk used in any interstate commerce.
The shelf life of refrigerated pasteurized milk is greater than that of raw milk. For example, high-temperature, short-time (HTST) pasteurized milk typically has a refrigerated shelf life of two to three weeks, whereas ultra-pasteurized milk can last much longer, sometimes two to three months. When ultra-heat treatment (UHT) is combined with sterile handling and container technology (such as aseptic packaging), it can even be stored non-refrigerated for up to 9 months.
According to the Centers for Disease Control, between 1998 and 2011, 79% of dairy-related disease outbreaks in the United States were due to raw milk or cheese products. They report 148 outbreaks and 2,384 illnesses (with 284 requiring hospitalization), as well as two deaths due to raw milk or cheese products during the same time period (per Wikipedia).
First, a Story:
An old couple won the lottery…
An old man and his wife; simple, salt of the earth folk, who never lived beyond their means, won the lottery.
Not wanting to lose their way with this sudden windfall, they decided to keep humble.
But as time went on, the husband wanted to treat his wife to expensive things – the things she always deserved but couldn’t give her. He remembered reading in a magazine about a new trend – milk baths – that were popular in the city, so he pointed his old truck towards the dairy farm down the road a ways.
He pulls up and the farmer greets him. “What can I do for you Amos?”
Amos says “Well you know, I’d been a reading bout these milk baths these fancy city folk been doing, and I’d like to buy enough milk to treat my wife to one. “
The farmer scratches his head and asks “Ok, you want it pasteurized?”
“Nah just give me enough to get up to her knees she can splash it up from there.”
Second, a Song:
Brandon Werner is the creator of the web series Laughing Historically, a Senior Designer at Maker Studios, and a consulting detective (per https://www.pinterest.ca/bbwerner/)
Here is his video “The History of Pasteurization: Killer Milk?!” I hope you enjoy this!
Thought for the Day:
“Let me tell you the secret that has led me to my goal. My strength lies solely in my tenacity.” – Louis Pasteur
In response to the Boston Marathon Smile:
Gerry Wahl of North Vancouver, BC, Canada writes:
“I loved running but the hip – and threats from the surgeon – ended it for me.
BUT now – I am walking 40-50 kms a week and – in fact –almost as fast as my former ‘enhanced shuffling’ “
and John Zeleznikow of Melbourne, Australia writes”
I have run Boston twice (2009 and 2010) and New York 5 times (1979, 1980, 1981, 1982, 1983). NYC 1980 was my personal best (3 hrs 19 min 45 sec).
On June 6 I will run my 200th marathon on my 71st birthday. I had hoped to do it for my 70th birthday, but we were in lockdown.
Editor: Congratulations John! An incredible accomplishment! And lifetime achievement!
Have a great day!
Dave & Colleen
© 2021 David J. Bilinsky and Colleen E. Bilinsky