Pasteurisation: Probably Why You Survived Childhood

There’s an oft-quoted maxim that youngsters growing up on farms have a much stronger immune system than those growing up in cities. The idea is that they are exposed to far more dirt and eat food much closer to the field than their urban cousins. Without the help of a handy microbiologist or epidemiologist it’s difficult to judge its veracity, but personal experience suggests that the bit about dirt may be true at least.

It’s Dangerous To Idealise The Past.

It’s likely that the idea of rural kids seeing more bugs may come from the idea that those in the cities consume sterile processed food from the supermarket, it plays into a notion of an idealised past in which a somehow purer diet came more directly from its source. Somehow so the story goes, by only eating pasteurised and preserved foods, city dwellers are eating something inferior, stripped of its goodness. There’s a yearning for a purer alternative, something supermarkets are only too happy to address by offering premium products at elevated prices. So, was the diet of the past somehow more wholesome, and are those kids having their future health ruined by Big Food? Perhaps it’s time to turn back the clock a little to find out.

A mostly black cow in a field of green grass
Even clean cows have bugs. Carolyn Parsons, CC BY-SA 4.0.

It’s likely everyone knows that food  spoils if left unattended for long enough. Some foods, such as grain, can last a long time if kept dry, while others such as milk will go bad quite quickly. Milk in particular goes bad for two reasons; firstly because it’s an excellent bacterial growth medium, and secondly because it contains plenty of bacteria by its very nature. Even very clean cows have bugs.

If you lived in most large cities in the nineteenth century, the Industrial Revolution had likely placed you far enough from the nearest cow that your milk had a significant journey to make to reach you even with up-to-date rail transport. Without refrigeration, during that journey it had become a bacterial soup to the extent that even though it might not yet have gone sour, it had certainly become a bacterial brew. It was thus responsible for significant numbers of infections, and had become a major health hazard. So much for the purer diet consumed by city kids of the past.

Heat ( and Louis Pasteur) To The Rescue

The knowledge that heat can be used to preserve food can be traced back hundreds or even thousands of years, and by the nineteenth century that had been developed into the bottling and canning processes which we use today. These rely on sealing food into a container, and cooking it in the container by placing it in boiling water, with the result being a can of perfectly cooked and preserved food which only requires heating to serve.

Portrait of Louis Pasteur
Louis Pasteur, who probably saved your life. Paul Nadar, Public domain.

Canning and bottling then have solved food preservation, but only for cooked food. Foodstuffs such as milk or juice don’t survive the process very well, as they cook, and their taste and texture is altered. Think of the taste of condensed milk, for example, which doesn’t quite make an acceptable substitute for fresh milk. And here we come to pasteurisation, the process of heating to a lower temperature for long enough to deactivate bacteria but not long or hot enough to cook the foodstuff. It’s the invention of the French biologist Louis Pasteur, and though we now associate it with milk, it was devised to stop wine from spoiling as it aged.

The beauty of pasteurisation is that it does not require specialised machinery to work; while it’s achieved commercially by passing the milk through steam-heated pipes, it can even be done in a saucepan on a domestic stove. The aim is to heat it as hot as possible without cooking the milk, and the exact temperature depends on for how long it will be heated. The result isn’t the sterility of a high-temperature canned food, but the active bacteria have been removed and its shelf life increased significantly. My experience with the process comes from home-pressed apple juice, and the figure I remember was 67 Celcius, the exceeding of which would impart an apple sauce taste to the final product.

Pasteurisation then is a major contributor to our public health. Far from bring a process somehow denying the kids a more wholesome food, it’s one of the reasons why many of the diseases that haunted our great-grandparents generation are now just names in print. Examining the process has provided a window into the perception of food though, as someone who did grow up on straight-from-the-cow unpasteurised milk did I have a better start in life? Probably not, but it did give me a keen sense of smell for soured cream.

Header image: Agriculture And Stock Department, Information Branch, Photography Section, Public domain.

124 thoughts on “Pasteurisation: Probably Why You Survived Childhood

  1. One of the major issues was handling: drinking milk from one cow wasn’t so much a problem even if the milk got shipped a ways. But once we got dairy cooperatives, the milk from thousands of cows got mixed together in huge collection systems, and then portioned out for consumers. That meant any sick cow’s milk got everyone. This was a huge issue for the spread of tuberculosis, which was a major cause of human mortality until the 1930’s.

    BTW there’s probably a cost to having that highly active immune system that people who are exposed to lots of dirt and bacteria are thought to have: the average body temperature of people has dropped measurably over the last 75 years, and a likely reason is that the number of people who have chronic inflammation and infections, which raise your body temperature as it tries to fight off the infection, has dropped with the advent of access to antibiotics.

    1. How often do you think those collection systems get thoroughly cleaned? Is that the reason for pasteurization or does it really have to do with bacteria from inside the cow as the article would suggest?

        1. I worked on a fairly big (at least in my country) milk processing plant (cheese, cream, butter, milk/whey powder etc.). Cleaning was done on regular basis (pipes and tanks) with base, acid and hot water. I don’t remember the rules but I think milk from one supplier was not mixed with other. We even joked that there is a chance to trace a cow that gave milk for your butter if only you present the package. Many people after working in food industry have bad opinion about what we eat. I can’t say that – for some time I was buying the products without hesitation. Later on company focused on profits by buying cheap and quality was poor. But it was related to bad management not bad hygiene.

      1. >Is that the reason for pasteurization or does it really have to do with bacteria from inside the cow as the article would suggest?

        There is evidence that milk ducts can be colonised by bacteria, potentially even after being translocated from the gut, and so milk will naturally contain microbes. This likely plays a role in setting up the gut microbiota of infants.

        Dirty equipment won’t help though, and microbes can breed rapidly in something like milk. They can also be damn hard to remove thoroughly.

      2. As one of the other people replied, in place cleaning of sanitary tubing with some sort of hot sanitizer is implemented at all places I know of that handle food grade liquids, but the other factor is how the sanitary tubing itself is constructed. Sanitary piping and sanitary grade welds more or less have to be polished smooth, which gives very little area for bacteria or mold to grow.

        1. Yes, and that’s why some of the best paid and most skilled TIG welders are those who weld food-grade piping. It’s critical to have smooth interior surfaces, especially inside pipe sections that can’t be accessed. Bad things grow in any nooks and crannies.

      1. Yeah, people talking about having a “strong” immune system are either misinformed or they’re selling snake oil. Nobody needs a “strong” immune system if all that strength goes into punching yourself in the face over and over every day forever.

        Medicine and hygiene has saved us from countless preventable deaths and illnesses, but our immune system evolved to calibrate itself by exposure to external insults, and unfortunately that means we get to choose between disease risk and auto-immune disease risk.

        1. My sister used to boast about her “healthy” immune system when she mocked me for washing my hands before I handled food. Then she discovered she was gluten intolerant because her healthy immune system was attacking her previously healthy intestines…

          1. Let me guess, she became gluten intolerant after the 2006 standardization of glyphosate as a wheat dessicant. There’s no amount of washing that’s taking that out of the flour.

          2. Correlation and causation are not the same thing. Celiacs have existed long before pasteurization along with ALL auto immune diseases. Lupus, one of the most severe autoimmune diseases gains it’s name because people looked like wolves and while there has been an increase in cases of about 2% in the last 40 years it’s not related to having an immune system that isn’t busy and needs something to do, most likely it is due to increased pressure more affordable basic healthcare and diagnosis!

        1. That is what’s called a ‘hypothesis’.

          Too clean an environment in childhood makes for sick adults.
          Allergies and autoimmune.

          Hard to test ethically. Confounding factors in public data. Animal models mostly say yes.

          I was told as a child that every person needs to eat two pecks of dirt in their lifetime. People naturally get fussier as they age. So one peck should be eaten in childhood.

          A peck is two bushels IIRC.

          1. From wikipedia, a peck is 1/4 bushel.

            2 pecks is about 0.6 cubic foot. That’s a lot of dirt. Eating that much dirt, even if it’s sterilized and spread over a lifetime, sounds like very bad advice.

  2. Pasteurisation is great, but it’s also dangerous to idealize modern tech. As smellsofbikes touched on, modern industrialization/logistics is the only reason pasteurization is needed. Same for stripping eggs of their protective coating. No need in rural areas with local supply. There’s also a cost. Pasteurization eliminates Vitamin C and some other nutrients. Synthetic nutrients can be added, but research has shown they’re not as good.

    1. Yeah, and ironically as much as these people like to rail on about the “idealization of the past” they forget that their own interventions have been heavily idealized as well. Lack of pasteurization is not why “you probably would have died as a child a couple centuries ago.”

      That’s stupid. Most of it was plumbing enabling some level of common sanitation, and the expansion of living space so that you aren’t crammed like sardines into a tenement block full of tuberculosis. Thank your carpenter and your plumber and farmer, the doctors and designers of industrial processes (who demand heroic credit VERY loudly) were secondary at best to these other improvements. Nearly all of those metrics were well on their way to the modern trend-line before they came along.

      1. Civil engineering has probably saved more lives than any other profession including doctors and medics. Having drinking water free of pathogens and prompt removal and treatment of sewage was a game changer in terms of infectious diseases.

          1. And who made it possible for those observations to be made? Oh, right, civil engineers when they implemented a variety of solutions. To say nothing of the engineers who made higher education at scale possible with inventions like the printing press.

          2. Civil engineers built the first sewers when ‘doctors’ were still bleeding people to balance humors and epidemiology amounted to prayer to one or more gods to stop the beating.

            Speaking of which even the old testament says ‘Bury you’re shit, for god walks in your camp.’ (para). DooDoorotomy IIRC.

          3. They didn’t just move shit away because it smelled.

            They knew it caused disease. Were confused as to mechanism. Many Doctors believed it was literally the smell.

            Who would have guessed that modern sewers would have come about during the industrial revolution?

            Very few medical doctors were/are scientists.
            In Pasteur’s day they were trained by _apprenticeship_. Generations of wrongness perpetuated. Rando doctor was an utter crapshoot.

            But modern doctors love to take credit.
            Like their forbears weren’t dispensing powdered mummy for everything.
            After giving up on bleeding for health, refusing to wash hands.

        1. I’ll see your CEs.
          I raise you agriculture.

          A whole lot of people died from starvation or malnutrition before people started managing their food supply.

          It may not win with raw numbers, but percentages?

          Also, CE sanitation happened due to medicae.

          Bonus Round: diplomats.

      2. And in order to have people who are engineers and plumbers and whatnot they must have the liberty to not be forced to grow their own food, which means a smaller part of the population grows the food which then has to be efficiently distributed to a large amount of people and so forth, meaning pasteurisation and other food safety methods are absolutely vital to a modern society.
        Then again, you did post some anti-vax nonsense below so I might be writing to a brick wall here.

      3. Idealizing the modern/future MIGHT sometimes be dangerous.
        Pushing the limits of a loophole so a company can make 1.3% more profit on an inferior product is obviously bad.

        But idealizing the past is almost ALWAYS dangerous.
        That path leads directly to dayime television fad diets/supplements, xenophobic nationalist “make America great again” rhetoric, racism, sexism, and much more.

        The past sucked for almost everyone.
        The “wisdom of the ancients” is a farce.

    2. What???? Milk must be heated ALWAYS, no matter if the cow is yours and you do all the work by yourself. Do you know what is Brucellosis? It was sadly common until pasteurization was invented.

      1. Never lived on a farm, have you? brucellosis is caused by INFECTED animals. Not ALL aminals. Most of us out here in farm country drink milk from our cows every day just fine, thank you.

    3. Oh stop it! Raw milk killed plenty of people. How long do you think it takes for room temperature raw milk to become a massive collection of bacteria colonies. It isn’t what is growing, it is how much. The load can easily overcome the most hearty immune system. Most of the time the bacteria are relatively harmless and they don’t produce dangerous toxins at a high level. But if they are unfriendly there can be very high concentrations, aaaand dead children.

    4. >As smellsofbikes touched on, modern industrialization/logistics is the only reason pasteurization is needed.

      I’m sorry but that’s not true. Raw milk still exists and people still drink it. Because of regulations they are forced out odd the regular channels and still use very small batches and hyper-local distribution. With modern cars, refrigeration, and better understanding of germ theory they likely have better milk than the people of the past.

      And yet, they get milk related food poisonings at a rate HUNDREDS of times larger than pasteurized milk drinkers

    5. No, people in rural areas don’t escape this nowadays, even if their plants or animals have never had direct contact with anyone else’s. There’s so much movement of people and goods that if something is in any area, it can get to any other area. And then a local bird or bug or something can carry it the rest of the way, if it can’t spread by other means.

    6. Synthetic nutrients can be added, but research has shown they’re not as good.

      Initial research may show that, but thorough research does not. For instance, synthetic vitamin E often consists of just alpha tocopherol, which is inferior to natural vitamin E. Further research has shown there are 8 constituents of vitamin E, four tocopherols and four tocotrienols. Better synthetic vitamin E contains more of the varieties.

      Similarly, many nutrients are naturally only right-handed or left-handed, whereas synthetic versions are often racemic (equally mixed). Further processing or different processes are needed to produce the desired handedness of a synthetic product.

      The blanket statement that synthetic nutrients are inferior is untrue, and reveals magical thinking.

    7. This is why I raise backyard chickens. That and all the talk of bird flu and the fact that most commercial chickens sit in their own feces all day should be convincing enough. Also, open a fresh farm egg. You can literally *see* the difference in nutrition in tone, consistency and color alone.

      To add on your point: most of these “additives” are mineral-based. I’m not opposed to enriching foods (it’s a major weapon against hunger) but when a company does it the cheap way as I mentioned, they’re essentially grinding rocks into your food.

    8. “modern industrialization/logistics is the only reason pasteurization is needed”

      No. No, it’s not. It’s very dangerous to cite modernity as an evil in this way. Believe me as someone who grew up on an organic small farm, pasteurisation is a useful tool when everything is done without any of the modernity, too.

  3. Modern dairy systems detect higher-than-normal temperatures in the milk, which signifies a possible illness in the cow, at the point of harvest and sequesters any milk gleaned from that animal. Most will notify the farmer to separate and quarantine that animal.

    1. I ran into that when installing a point-to-point wi-fi system* for a dairy farmer. The cattle have eartags with temperature sensors (presumably with replaceable batteries?). As the cows are funnelled into the milking shed, any tag that reads elevated temperature triggers an automatic gate that prevents that cow from entering the milking shed – it gets shunted to another pen for further investigations. A fantastic use of technology.

      *He needed to transmit the milking data from the milking computer in the milking shed to the milking computer in the milking residence, where it was uploaded to some milking database. He was very grateful to no longer have to transfer the milking data via milking USB to the milking computer :-)

    2. On a farmstay, I’ve drunk raw milk, straight from a cow’s teat into a bottle. Delicious, warm, frothy, and creamy.

      Then I took a couple of bottles to the cabin and put them in the fridge. Drank them in cereal and coffee over the next few days. Towards the end of day 3, they developed a pleasant sour smell, a but like sauerkraut or kimchi. What a surprise to find lactobacillus! I proceeded to make sourmilk pancakes. I didn’t die, or even get sick.

      Outside those narrow parameters of local harvest and immediate refrigeration in clean containers I wouldn’t recommend it, but everyone should try it at least once.

      1. I occasionally buy unpasteurised and non homogenised milk direct from a local dairy farm, it’s a lot nicer than the processed milk I usually buy but that may just be because it’s a higher quality product from less intensively farmed animals and it really does go off a lot more quickly.

      2. Anecdotal but true: I grew up drinking fresh-from-the-cow, whole (cream and all), unpasteurized, delivered still warm, two gallons per week, in the trunk of a ratty old Plymouth Valiant driven by the hands that milked the cow, in reused glass jars, sealed only with a layer of wax paper between the lid and the jar.

        We did keep it refrigerated.

        None of my family of six seemed to have had adverse reactions.

  4. I just came back from a family reunion. We were just reminiscing on the joys of unpasteurized, non-homogenized milk that we had when we were kids. After it was overnight in the fridge we (the kids) would sneak in and skim the cream off the top for morning porridge. If we wanted more milk we’d just go to the barn and fill a pitcher from the collection tank. It was filtered and chilled, but that’s it.

    The most interesting thing was how the taste changed with the seasons, with what the cows ate. It’s all just the same taste now, from the grocery store.

    Yeah, that extra-virgin stuff doesn’t age well or travel well, but it sure was good. It was one of the bits that made up for growing up in what was otherwise the arse end of civilization.

    1. Yeah it’s quite good, too bad most people will never know a thing about it. It’s kind of a shame.

      And if you ended up on the wrong end of it, death really isn’t the result if you’re in good health otherwise… More like a fresh pair of pants are in order. People aren’t as fragile as they were in the Upton Sinclair days.

    2. I think that you are confusing the pasteurization process with the normalize of cream in milk. Today, milk is first stripped of all the cream and then a specific quantity is restored for whole milk, to keep the quantity stable during the whole year (and also because cream is used for other products). Also, today milk is homogenized, which consists simply in passing it through a tiny hole to make it hit a wall, thus ensuring that there are no lumps/clots of cream, and it is uniform. That last thing is what really prevents to form cream on the top. Those two things are what really change the taste of the milk, not the pasteurization process.

      I tasted direct-from-cow milk too when I was a kid and it was like you say, but my mother always heated it previously to ensure that there was no risk.

    3. I milked cows for fifty years plus five months. I learned that different forages that cows ate would flavor the milk. When I was young we had a few Guernseys my grandfather milked before I started in 1971. When they were let out on pasture for the first week the milk tasted so much like grass we had to add blobs of Nestle’s Quick to make it even partially drinkable.

  5. Bumper sticker–obviously directed at the ‘ant-vaxxer’ crowd–seen the other day (are bumper stickers a ‘thing’ amongst people of the British persuasion?), and offered in light of Pasteur’s work on the germ theory of disease, and vaccination—

    “Q: Should you vaccinate your children?
    A: Only those you want to keep.”

        1. I had to think really hard about why one would ever pasteurize wine. I’ve made a lot of wine and it doesn’t go bad, it ages and gets better. Made even more beer along the way too but beer is boiled so that makes sense I guess.
          But modern winemaking in clean glass and stainless with pitched monoculture yeast is certainly a much different process than in the boat with sulfured wood fermenters. Makes sense undesired bugs would make their way in more often than not.
          Oh also if you’re ever in pairs you can go to Pasteur’s house. It’s amazing.

      1. Could easily be!

        But since we’ve figured basic sanitation out pretty well since the Great Plague, you’ve got vaccines to clean up some of the rest of diseases that aren’t caused by ingesting feces. Of which there are many.

        1. “But since we’ve figured basic sanitation out pretty well since the Great Plague”
          Not sanitation but pest control. Hand washing and clean drinking water won’t prevent rat flees from spreading diseases.

    1. Says so right on the tin: Ultra High Temperature. 135 C and higher, cooks and kills everything. “Ordinary” milk pasteurization is “16s”: 160 F for 16 seconds, or 60 C for 16 minutes (or was, anyway — not sure what’s current).

      1. “cooking” requires time and UHT is faster than pasteurization, so not much cooking going on really, and more effective sterilization against more kinds of bacteria.

  6. I initially mis-read the headline as “Pasteurization: Why You PROBABLY Survived Childhood” and thought: Dang, there’s pretty decent internet in the afterlife, huh?

  7. This article has given me an idea, The Great British Raw Water Company, water straight from UK rivers sold in bottles where the label is mainly a Union Jack, to be exclusively sold in Wetherspoon’s…

  8. Pasteur was a genius. As well as inventing pasteurisation he disproved the millennia-old theory of spontaneous generation by showing that the spoiling of foods required them to be exposed to spores in the air, and produced the Pasteur treatment against rabies. From what I have read Pasteur treatment is unpleasant, but it’s still better than a horrible death.

    1. If you go to pasteur’s house in paris (do this! But make a reservation … or as noted above they won’t let you in) they have right there on the lab shelf the original broth he boiled to show germ theory was legit. Right there on the shelf.
      What I also learned was the he was Teh Science. Solved a whole bunch of other problems (wine grape blights, sheep problems …) and it’s all there in mosaic form in the crypt where he is buried . Right there under the entry way to his house. It’s gorgeous and poignant.

  9. I’ve had raw milk a few times with no problems

    Pasteurization kills good things in the milk

    also fermentation was sometimes used to prolong shelf life of foods that would otherwise go bad (dunno about milk)

    a lot of foods can be eaten raw without issues, some people even eat raw meat and eggs for years without illness

  10. Here’s a hypothesis for someone else to test…

    Author is right that country kids get exposed to more micro-organisms. But city kids get exposed to more germs. A lot of what is out there in nature is adapted to attack a different host species and so not all that relevant to us while in the city with all those people jammed together human pathogens can spread much more easily.

    All that said… I see people taking this (you need exposure to exercise your immune system) thing way to far. Nobody is advocating living in sealed bubbles. We are surrounded by organisms no matter where we are, how we clean, what we eat or what vaccines we take. Any of them would just love to chow down on the raw materials our bodies are made of but our immune systems don’t allow it. The idea that someone is at a disadvantage because they are too clean? I really doubt that! You are killing millions of organisms with every breath!

    One last bubble to pop. Farm life is oh so healthy… well in the past it was a great place to be exposed to all sorts of pesticides and fertilizers that we hadn’t learned were bad for us yet. Let’s pretend we’ve found them all and discontinued all of them… The classic family farm is getting rare. Instead we have factory farms where animals are crowded on an industrial scale and everything is contaminated with E-Coli and/or Salmonella. There are rivers that run poop brown or blood red depending on if it is animal raising season or butchering time!

    Obviously we need farming and with 8 billion mouths to feed it isn’t going to be pretty. But let’s not overly romanticize it. That sort of thinking tends to feed into too many harmful political views.

  11. I worked a raw milk dairy farm in WA state during the COVID shutdowns. It was a truly amazing operation. The owner had a masters in microbiology from WSU and had bred her Jersey cows to produce a specific protein that was better/easier for humans to consume. She’d been tracking the bloodlines and culling for that particular trait alongside longevity and health.

    It was kind of odd seeing a chemistry lab set up in the barn right next to all the normal farm hardware associated with cattle. They only had one batch of infected milk in the 15 plus years they’ve been in operation. After that one incident they doubled down on an already “clean freak” operation to make it more so. It was a lot like brewing craft beer to be honest. Their customers would often buy two gallons of milk and let one sit out to make cheese with it. So raw milk has its benefits I think, but you have to treat it (and the process to make it) with a great deal of respect.

    Coolest part was how they used a heat pump to chill the milk down to near freezing and transfer that heat to a heavily insulated hot water tank so the whole farm had hot and cold water on tap for clean up.

  12. Hot take- most of the commenters are all correct. This is yet another example of the distinction between individual-level and population-level statistics/experiences/science/etc.
    It’s like COVID and masks or wearing seat belts or guns or even smoking or any other example- on the individual level your risk is very low- minuscule actually. Plenty of individuals can eat or drink whatever they want and the risk is so low that it is practically zero.
    But practically zero is not zero. On a population level of millions, tens or hundreds of millions of people, even very small risk equates to a large absolute number of cases/victims/injuries etc.
    So everyone that says “eh, unpasteurized foods are fine” and ALSO everyone that says “no no it is dangerous!” are ALL correct.
    How you square that conflict is no longer the realm of science, but politics.

    1. However there is probably also a calculable amount of health that is reduced from pasteurization which adds up as a trade off over time. Let’s say every glass of raw milk gives you one second more of life over a pasteurized glass. It may also take moments of life more to pasteurize milk. Add up all those seconds of the cost of safety and it may outweigh the cost of a few people dying of contamination.

      This is also an issue with seat belts and other security measures like wearing helmets when bicycling; there are opportunity costs of “safety” sometimes neglected in calculating the risk and possible reward involved in certain decisions.

      1. Statistics is math. A tool used by science.

        Incompletely/incompetently cited statistics are certainly politics.
        Reporters are generally innumerate, as are most viewers/readers.

        Trust the science, never trust science reporting.

  13. When I worked as a paramedic I would be exposed to everyone’s illnesses and I rarely ever got sick. There’s something to be said for exposure to pathogens and having a good immune system.

  14. With pasteurization, we avoid things like Listeria infection, which can be fatal in children. With vaccines babies avoid things like Rubella, which can cause blindness and deafness. And we can prevent Rh disease in newborns by giving mothers an Rh immunoglobulin shot.
    Science and modern medicine is pretty awesome.

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