The science of milk - Jonathan J. O'Sullivan
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0:08 - 0:11Why do humans drink so much milk?
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0:11 - 0:13And given that all mammals lactate,
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0:13 - 0:17why do we favor certain types of milk
over others? -
0:17 - 0:19Milk is the first thing we drink,
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0:19 - 0:22and thanks to developments in the
production and variety of dairy products, -
0:22 - 0:28it can take on countless forms for our
dietary and sensory well-being. -
0:28 - 0:33Milk's primary function is as a complete
source of nutrition for newborns. -
0:33 - 0:37In fact, since it has all of the vital
nutrients for development and growth, -
0:37 - 0:38proteins,
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0:38 - 0:38carbohydrates,
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0:38 - 0:39fats,
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0:39 - 0:41vitamins and minerals,
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0:41 - 0:42and water,
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0:42 - 0:45milk is the only thing a baby
even needs to ingest -
0:45 - 0:48for the first six months of life.
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0:48 - 0:51The unique makeup of milk can vary
depending on factors like species, -
0:51 - 0:52diet,
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0:52 - 0:54and location.
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0:54 - 0:56Reindeer of the Arctic Circle,
for example, -
0:56 - 0:59make energy-dense milk
that's about 20% fat, -
0:59 - 1:03roughly five times more than human
or cow's milk, -
1:03 - 1:06to help their young survive the harsh,
freezing climate. -
1:06 - 1:08So how is milk made?
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1:08 - 1:11In the uniquely mammalian process
of lactation, -
1:11 - 1:15a special class of milk-secreting cells
known as mammocytes -
1:15 - 1:20line up in a single layer around
pear-shaped alveoli. -
1:20 - 1:23Those cells absorb all of the building
blocks of milk, -
1:23 - 1:26then synthesize tiny droplets of fat
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1:26 - 1:30on structures called
smooth endoplasmic reticula. -
1:30 - 1:33The droplets combine with each other
and other molecules -
1:33 - 1:38and are then expelled and stored
in spaces between cells. -
1:38 - 1:42Mammary glands eventually secrete the milk
through the breasts, udders, -
1:42 - 1:47or, in the rare case of the platypus,
through ducts in the abdomen. -
1:47 - 1:50Although this process is typically
reserved for females, -
1:50 - 1:53in some species, like dayak fruit bats,
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1:53 - 1:54goats,
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1:54 - 1:55and even cats,
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1:55 - 1:58males can also lactate.
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1:58 - 2:01Milk drinkers worldwide consume
dairy from buffalo, -
2:01 - 2:02goats,
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2:02 - 2:02sheeps,
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2:02 - 2:03camels,
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2:03 - 2:04yaks,
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2:04 - 2:05horses,
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2:05 - 2:06and cows.
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2:06 - 2:09Almost all of these species are ruminants,
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2:09 - 2:12a type of mammal with
four-chambered stomachs -
2:12 - 2:15that yield large quantities of milk.
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2:15 - 2:18Of these, cows were the most
easily domesticated -
2:18 - 2:22and produce a milk that is both
easily separated into cream and liquid -
2:22 - 2:25and has a similar fat content
to human milk. -
2:25 - 2:27In their natural environment,
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2:27 - 2:31mammals secrete milk on call
for immediate consumption by their young. -
2:31 - 2:34But with the demands of thirsty consumers,
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2:34 - 2:38the dairy industry has enlisted methods
to step up production, -
2:38 - 2:39enhance shelf life,
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2:39 - 2:43and provide a variety of milk products.
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2:43 - 2:47In the dairy, centrifugation machines
spin milk at high speeds, -
2:47 - 2:52forcing less dense fats to separate
from the liquid and float up. -
2:52 - 2:53After being skimmed off,
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2:53 - 2:57this fat, known as butterfat,
can be used in dairy products -
2:57 - 2:58like butter,
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2:58 - 2:58cream,
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2:58 - 3:00and cheese.
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3:00 - 3:04Or it can be later added back to
the liquid in varying proportions -
3:04 - 3:06to yield different fat content milks.
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3:06 - 3:14Full fat milk, sometimes referred to
as whole milk, has 3.25% butterfat added -
3:14 - 3:18compared to 1-2% for low
and reduced fat milk, -
3:18 - 3:21and less than half a percent
for skim milk. -
3:21 - 3:25To stop reseparation of the fat
from the water, or creaming, -
3:25 - 3:30the mixture undergoes the high-energy
pressurized process of homogenization. -
3:30 - 3:34Before milk hits the shelves, it's also
typically heat treated -
3:34 - 3:36to reduce its level of microbes,
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3:36 - 3:38a government-sanctioned process
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3:38 - 3:42that raw milk enthusiasts argue
may reduce milk's nutritional worth. -
3:42 - 3:46Milk spoilage is started by microbes,
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3:46 - 3:49which consume and break down
the nutrients in milk. -
3:49 - 3:52That process causes butterfat
to clump together, -
3:52 - 3:56leading to a visually unpleasant product.
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3:56 - 3:58And the byproducts of
the microbes' consumption -
3:58 - 4:02are compounds that taste
and smell nasty. -
4:02 - 4:03But there's a bigger problem.
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4:03 - 4:08Raw milk can carry microbes that are
the sources of deadly diseases, -
4:08 - 4:12so in order to kill as many of those
microbes as possible, -
4:12 - 4:13and keep milk fresh longer,
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4:13 - 4:17we use a technique called pasteurization.
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4:17 - 4:19One version of this process involves
exposing milk -
4:19 - 4:22to about 30 seconds of high heat.
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4:22 - 4:26Another version,
called ultra-high temperature processing, -
4:26 - 4:27or ultra pasteurization,
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4:27 - 4:33blasts the milk with considerably higher
temperatures over just a few seconds. -
4:33 - 4:36UHT milk boasts a much longer shelf life,
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4:36 - 4:39up to twelve months unrefrigerated,
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4:39 - 4:42compared to pasteurized milk's
two weeks in the fridge. -
4:42 - 4:45That's because the higher temperatures
of UHT processing -
4:45 - 4:48inactivate far more microbes.
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4:48 - 4:50Yet the higher processing temperatures
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4:50 - 4:55may adversely affect the nutritional
and sensory properties of the milk. -
4:55 - 4:58Ultimately, that choice lies
in the consumer's taste -
4:58 - 5:00and need for convenience.
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5:00 - 5:02Fortunately, there are many
choices available -
5:02 - 5:08in an industry that produces in excess
of 840 million tons of products each year.
- Title:
- The science of milk - Jonathan J. O'Sullivan
- Description:
-
View full lesson: http://ed.ted.com/lessons/the-science-of-milk-jonathan-j-o-sullivan
The milk industry produces in excess of 840 million tons of products each year. Why do humans drink so much milk? And given that all mammals lactate, why do we favor certain types of milk over others? Jonathan J. O’Sullivan describes how milk is made.
Lesson by Jonathan J. O'Sullivan, animation by TED-Ed.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 05:24
Jessica Ruby approved English subtitles for The science of milk - Jonathan J. O'Sullivan | ||
Jessica Ruby accepted English subtitles for The science of milk - Jonathan J. O'Sullivan | ||
Jessica Ruby edited English subtitles for The science of milk - Jonathan J. O'Sullivan | ||
Jennifer Cody edited English subtitles for The science of milk - Jonathan J. O'Sullivan | ||
Jennifer Cody edited English subtitles for The science of milk - Jonathan J. O'Sullivan |