The science of milk – Jonathan J. O’Sullivan

Why do humans drink so much milk? And given that all mammals lactate, why do we favor certain types of milk
over others? Milk is the first thing we drink, and thanks to developments in the
production and variety of dairy products, it can take on countless forms for our
dietary and sensory well-being. Milk’s primary function is as a complete
source of nutrition for newborns. In fact, since it has all of the vital
nutrients for development and growth, proteins, carbohydrates, fats, vitamins and minerals, and water, milk is the only thing a baby
even needs to ingest for the first six months of life. The unique makeup of milk can vary
depending on factors like species, diet, and location. Reindeer of the Arctic Circle,
for example, make energy-dense milk
that’s about 20% fat, roughly five times more than human
or cow’s milk, to help their young survive the harsh,
freezing climate. So how is milk made? In the uniquely mammalian process
of lactation, a special class of milk-secreting cells
known as mammocytes line up in a single layer around
pear-shaped alveoli. Those cells absorb all of the building
blocks of milk, then synthesize tiny droplets of fat on structures called
smooth endoplasmic reticula. The droplets combine with each other
and other molecules and are then expelled and stored
in spaces between cells. Mammary glands eventually secrete the milk
through the breasts, udders, or, in the rare case of the platypus,
through ducts in the abdomen. Although this process is typically
reserved for females, in some species, like dayak fruit bats, goats, and even cats, males can also lactate. Milk drinkers worldwide consume
dairy from buffalo, goats, sheeps, camels, yaks, horses, and cows. Almost all of these species are ruminants, a type of mammal with
four-chambered stomachs that yield large quantities of milk. Of these, cows were the most
easily domesticated and produce a milk that is both
easily separated into cream and liquid and has a similar fat content
to human milk. In their natural environment, mammals secrete milk on call
for immediate consumption by their young. But with the demands of thirsty consumers, the dairy industry has enlisted methods
to step up production, enhance shelf life, and provide a variety of milk products. In the dairy, centrifugation machines
spin milk at high speeds, forcing less dense fats to separate
from the liquid and float up. After being skimmed off, this fat, known as butterfat,
can be used in dairy products like butter, cream, and cheese. Or it can be later added back to
the liquid in varying proportions to yield different fat content milks. Full fat milk, sometimes referred to
as whole milk, has 3.25% butterfat added compared to 1-2% for low
and reduced fat milk, and less than half a percent
for skim milk. To stop reseparation of the fat
from the water, or creaming, the mixture undergoes the high-energy
pressurized process of homogenization. Before milk hits the shelves, it’s also
typically heat treated to reduce its level of microbes, a government-sanctioned process that raw milk enthusiasts argue
may reduce milk’s nutritional worth. Milk spoilage is started by microbes, which consume and break down
the nutrients in milk. That process causes butterfat
to clump together, leading to a visually unpleasant product. And the byproducts of
the microbes’ consumption are compounds that taste
and smell nasty. But there’s a bigger problem. Raw milk can carry microbes that are
the sources of deadly diseases, so in order to kill as many of those
microbes as possible, and keep milk fresh longer, we use a technique called pasteurization. One version of this process involves
exposing milk to about 30 seconds of high heat. Another version,
called ultra-high temperature processing, or ultra pasteurization, blasts the milk with considerably higher
temperatures over just a few seconds. UHT milk boasts a much longer shelf life, up to twelve months unrefrigerated, compared to pasteurized milk’s
two weeks in the fridge. That’s because the higher temperatures
of UHT processing inactivate far more microbes. Yet the higher processing temperatures may adversely affect the nutritional
and sensory properties of the milk. Ultimately, that choice lies
in the consumer’s taste and need for convenience. Fortunately, there are many
choices available in an industry that produces in excess
of 840 million tons of products each year.

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24 Responses

  1. igobivo says:

    Rare ted video i disliked 🙁

  2. Indiematic says:

    T I T T Y J U I C E

  3. DramaticDraggo says:

    Milk is just filtered blood.

  4. Mandar Rane says:

    Can I use the parts of these videos to demonstrate & training purpose?

  5. Rabiah Pascall says:


  6. Leema says:

    Lactose intolerants left the chat

  7. Mendez Incorporation says:

    Unless your lactose intolerant

  8. Peroroncino says:

    I thought Jonathan was an archaeologist

  9. Tricus pidbard says:

    Where are my Oreos 🅱️

  10. Neelima Goturi says:

    I’m lactose intolerant why am I here??

  11. Andrew&Olga says:

    So Gaylord Focker from Meet the parents wasn’t lying.

  12. Delta Squad says:

    The science of YEET

  13. Me Every Morning says:

    You need some milk

  14. mafarmerga says:

    Milk is actually a type of sweat, originally produced not to feed young but as a way of distributing anti-microbial peptides over the surface of the animal.

  15. Sprout Does Stuff says:

    I saw the thumbnail I was like educational tiddy 👀

  16. Corn Storm says:

    The title is a seed for a jungle in minecraft.

    The science of milk -Jonathan J.

    I cut out a space so the . would fit.

  17. Russell from Up says:

    Wait so first 6 months of life a baby doesn’t need food but just need milk? Interesting taking notes

  18. Rosalind Kincannon says:

    Do brown cows give chocolate milk ?

  19. Mikal Madsen says:

    I wanted to know more about the effects of human milk vs formula on babies' development. The bit about cells was interesting, but otherwise I feel like you wasted my time.

  20. Tinka Like AngelOK says:

    I rather milk my oats 🤷🏼‍♀️

  21. BLINKDARA says:

    I hate milk.

  22. BmnGameBoy says:

    Reindeer of the arctic circle🎶 sounds like a line in a song

  23. • Jen Dog • says:

    “Why do humans drink so much milk”
    Me: I don’t

  24. mexicano soy says:


  25. Huitzilli says:

    I don't Drink cows milk. 🐄 🍼 I'm not a cow. Lol

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