In this video we're going to learn some
basic barista science about milk,
how to heat and texture milk to form a
delicious base for drinks,
and how to pour it to make drinks look pretty. 
Before we start steaming and pouring milk,
it is important to learn some basic
milk chemistry and the rules that govern the way we treat milk when we steam it.
As far as we're concerned as baristas, milk consists of three main components:
sugars, proteins, and fats.
Let's discuss each one and the role it plays in both preparation and taste.
Let's start with sugars. The main sugar in milk is lactose and is actually very sweet.
This explains by well heated and
textured cappuccinos and lattes often
don't need extra sugar to taste sweet.
This plays a role in the temperature of
our beverages because we want to taste
every bit of sweetness we can pull out of the milk.
Imagine a fresh piping hot piece of pizza. If you put it in your mouth immediately,  all you taste is heat and pain.
If you let that same pizza cool a little, though you can taste everything that's delicious and wonderful about
melted cheese and saucy bread. By the
same logic then you don't want your
lattes to be too hot to taste all that
lovely lactose next up our proteins.
Proteins begin as coiled balls in cold
milk and through the addition of heat
uncoil to expose a hydrophilic (or
water-loving) end and hydrophobic (or water hating) end.
When we pull air into the milk with the steam wand the
hydrophobic ends of the proteins will
hide from the water in the milk inside
the air bubble causing the hydrophilic
ends to form a barrier around the bubble
keeping its shape. This is known as a
surfactant.
The surfactant qualities of proteins are
what holds the air bubbles together to
create milk foam and will keep its shape
until about a 160°F (or 71°C),
at which point the proteins will fall
apart or denature.  This causes the air
bubbles the proteins are holding to pop
and the milk foam to deteriorate-- yet
another reason we don't want to steam
too hot. Our third and final milk
component is fat. Fats affect the
thickness of the milk and quality and
longevity of the foam. The more fat
present in the milk the thicker the
liquid and the longer the foam will last.
Imagine milk foam as a series of bubbles
stacked on top of one another. In between
each one of these bubbles is a tiny
space that will let liquid fall through
it. The more fat present in the milk the
thicker that liquid will be and the
longer it will take to fall between the gaps
and the bubbles, creating a stiff
dry layer of foam on top of liquid milk.
The other effect fats have on the
steaming process is that it gives the
hydrophobic parts of proteins another
option to hide inside. The less fat
present in milk, the more the proteins
will focus on the air we inject, creating
larger amounts of foam. Now that we've
talked about the three main components
in milk, let's discuss four key
temperatures and how they affect each
component. Our first temperature is 40°F (4°C) or right out of the fridge.
At this point the sugars are too cold to
really taste, the proteins are in coiled balls,
and the fats are in solid globules.
Let's add some heat and see what happens.
Next up is a 100°F (37°C) or about
people temperature. Here the sugars are
just starting to get yummy, the proteins
are uncoiling, and the fats are melting
into oils. Because the fats are going
from a solid to a liquid, it gives the
proteins another option of something to
grab on to, disrupting foam formation.
It's for this reason that we want to
stop adding air when the milk reaches a
100°F (37°C), when it's just starting
to feel warm. At 140°F (60°C),
the sugars are in full effect,
the proteins are uncoiled, and all the
fats have turned to oil. This is our
ideal tasting temperature, so stop the
steaming process once the milk is 140°F (60°C) or too hot to touch.
At 160°F (71°C), the sugars are too hot
to taste, the proteins are denaturing, and
the fats... well I guess they're doing just
fine. At this point, not only is the milk
not sweet and the foam starting to fail,
but the taste of denatured protein is
bitter and eggy--a poor complement to
espresso. Now that we have a basic
understanding of the rules behind milk
steaming, let's talk about the process.
The first step is steaming perfectly
textured milk for an espresso beverage
is to determine the right amount of cold
milk to pour into the appropriately
sized pitcher for that drink. The final
volume of milk in the pitcher after
steaming should equal the volume of the
drink you're about to pour, and with
about an ounce (30mL) of espresso already taking up room in the cup, that should
leave you with an ounce of milk (30mL) left
over in the pitcher when you're through pouring.
For lattes we want 25%
aeration and for cappuccinos, 50%.
Therefore the amount of cold milk you
pour into the pitcher at the start
should be such that after aeration
you've attained the volume of the drink
you're about to pour. Now let's go
through each base espresso drink from
smallest to largest and talk about how
much cold milk to pour into which
pitcher for that drink.
Let's start with cappuccinos and cortados to stay.
In most steaming pitchers the bottom of the spout indicates the halfway point for the total volume of the pitcher. Therefore for this six ounce (178 mL) drink,
pour in 3 ounces (88 mL) of cold milk
to reach halfway to the bottom of the
spout. After aeration the foam should
reach the bottom of the spout, totaling
six ounces (178 mL) of aerated milk at 50%, just
enough to fill the cup. For eight ounce (236 mL) cappuccinos
to go, pour in four ounces (118 mL) of
cold milk to reach just below the bottom
of the spout. After aeration the milk
should reach halfway up the spout,
totaling eight ounces (178 mL) of aerated milk at
50%. For an 8 ounce (236 mL) latte to go pour 6 ounces (178 mL)
of cold milk into a 12 ounce (355 mL)
steaming pitcher to reach the bottom of
the spout.  After aeration, the milk should
reach halfway up the spout for 8 ounces (236 mL)
of total steamed milk aerated at 25%.
For a 12 ounce (355 mL) latte, pour 9 ounces (266mL) of
cold milk into a 20 ounce (590 mL) steaming
pitcher, to reach just below the bottom
of the spout. After aeration the milk
should reach .25 of the way up the
spout, totaling 12 ounces (355 mL) of steamed milk
at 25% aeration. For a 16-ounce (473 mL) latte use
a 20 ounce (590 mL) steaming pitcher and pour in
12 ounces (355 mL) of cold milk to reach just
above the bottom of the spout. After
aeration the milk should reach .75 of
the way up the spout for 16 ounces (473 mL) of
steamed milk aerated at 25%.
Because steaming pitchers taper up from
the bottom, it will appear as though you
have more foam in this size than others.
Last but not least, for a 20 ounce (590 mL) latte
use a 36 ounce (~1L) steaming pitcher and pour
in 16 ounces (473 mL) of cold milk to reach just
below the bottom of the spout.
After aeration the milk should reach a
.25 of the way up the spout,
totaling 20 ounces (590 mL) of steamed milk
aerated at 25%. Now that we know
the percentages of aeration for lattes
and cappuccinos and which pitchers to
use for which drinks, let's talk about
the mechanics of using the espresso
machine steam wand to create perfectly
textured milk. We'll do these
demonstrations with milk enough for a 12
ounce (355 mL) latte. We'll begin by using a 20
ounce (590 mL)  steaming pitcher and filling it
with 9 ounces (266 mL) of cold milk to reach
just below the bottom of the spout.
At the machine begin by opening the steam
valve for at least one second to remove
any condensation from inside the steam
wand and prevent injecting your milk
with water next position the steam wand
at a 10 to 20 degree angle straight out
from the machine
this will position all the holes on the
steam wand tip at a downward angle,
allowing it to pull air into the milk
instead of skipping it across the
surface. Next submerge the steam wand
into the milk just to the point where
the steam wand tip screws into the steam
wand itself. This will allow you to open
the steam valve all the way without
immediately pulling in air. Tilt the
pitcher slightly to one side or the
other allowing the angle of the steam
wand to push the milk in a circular
motion around the pitcher. This allows
you to control the high water mark in
the pitcher and inject air only when you
choose to. In one motion open the steam
valve all the way and lower the pitcher
until you hear the steam wand
start to pull air into the milk.
The proper amount of aeration should
sound like constant paper tearing. If it
sounds like an intermittent chirp it
means you're not adding enough air and
should lower the pitcher more. If it
sounds like TV static, you're adding too
much air and should raise the pitcher
slightly. Continue to consistently add
air until the side of the pitcher feels
warm to the touch or you have the
appropriate amount of aeration, whichever
comes first.
To stop aerating, raise the pitcher just
enough to resubmerge the holes in the tip
of the steam wand. Hold this position
allowing the steam wand to heat and
swirl the milk in the pitcher until it
is 140°F (60°C) or too hot to touch.
Once the milk is hot enough turn off the
steam valve in one motion lower the
pitcher to the counter, purge out any
residual milk on the inside of the steam
wand, and thoroughly clean the outside of
the steam wand with a damp cloth.
Now let's see the entire process live from
two different angles.
Even if everything goes perfectly there
might be some small blemishes on the
surface of the milk when you're through.
So tap the pitcher on a hard surface to
pop any visible bubbles and swirl the
milk for at least three seconds until
it's glossy and shiny like wet paint or
marshmallow fluff. So far we've seen what
happens when things go well so now let's
see what happens when we add not enough
and too much air. If you don't add enough
air before the milk reaches a 100°F (37°C),
there won't be enough foam
present in the milk to buffer the sound
of aeration causing it to screech in
pain as you steam it.
The end result is aerated milk with a
thin watery texture and bubbles that
won't pop out when you tap the pitcher.
Another result of not aerating enough is
that the milk won't expand. This means
you won't have enough steamed milk in
the pitcher to fill the customers cup. If
you add too much air the amount of foam
you're creating will buffer the sound of
steaming entirely making the whole
process whisper-quiet.
The result is thick pillowy foam that
stiffens quickly and is difficult to
pour. So far we've talked about some
basic milk chemistry and the rules that
govern the way we treat milk when we
steam it. We've also discussed good
techniques to steam appropriate amounts
of milk into a delicious well textured
base for lattes and cappuccinos. So now,
without further ado, let's finally get to
the reason you've skipped ahead to this
part of the video: Latte art. A good way
to think about latte art is like plating
for a chef. You've taken your time to
craft a delicious shot of espresso, and
you've played by all the rules we've
talked about so far to create a
perfectly textured milk base that will
taste great with it. Latte art is your
chance to grab the customer's attention
and communicate to them that this drink
is going to be amazing. The first
variable we'll talk about is height or
the distance of the spout of the pitcher
from the surface of the liquid in the
cup. Imagine a bubble of milk foam as a
white ball we're dropping into a colored
liquid. If the ball is submerged in the
liquid it will be stained that color
when it pops back up to the surface,
whereas if the ball remains on the
surface of a liquid, it will stay white.
Dropping the ball from higher-up
guarantees that it will submerge when it
hits the liquid, whereas dropping it from
lower will keep it on the surface.
The goal of any latte art design is a crisp
white design on a dark brown surface.
To accomplish this contrast we want to be
mindful of three main heights that we
can control while pouring. The first is
three inches (7.6 cm) above the surface of the
liquid in the cup. This will cause the
milk foam to plunge below the surface of
the espresso keeping the surface of the
liquid in the cup dark brown.
The second important height is about one
inch (2.5 cm) above the liquid in the cup.
This will cause some of the foam to submerge
and some to float resulting in an
undesirable hazy beige color. The way to
make sure your design is crisp white is
to keep the spout of the pitcher within
a quarter inch (.6 cm) of the liquid in the cup
when pouring the design. Just like in the
ball analogy, pouring with the spout of
the pitcher this close to the liquid in
the cup prevents the foam from
submerging below the espresso and allows
it to retain its vibrant white color. In
order to get as close as possible as
soon as possible tilt the cup at a
thirty to forty-five degree angle and
make sure the pitcher is touching the
lip of the cup the entire time you're
forming the design. Watch what happens
when the cup is kept flat and the
pitcher rests on the rim of the cup.
First nothing appears then beige then
crisp white as the liquid in the cup
approaches the spout of the pitcher
now here's what to do to control this
process begin by tilting the cup about
45 degrees and start pouring from a
height of above three inches (7.6 cm) to fill the
cup without having any design show up on
the surface. As soon as the liquid
reaches the rim of the cup stop pouring
to avoid the beige area entirely and
touch the pitcher to the rim of the cup.
Quickly resume pouring with the pitcher
touching the cup. To pour a crisp white
design be sure to slowly untilt the
cup to keep from spilling as it fills.
A good rule of thumb here is that if any
beige appears in your design that means
the spout of the pitcher was not within
a quarter inch (.6 cm) of the liquid in the cup,
meaning that our that the cup was not
tilted enough to let the pitcher reach
the liquid or the pitcher was not
touching the rim of the cup. The next
variable we had the tackle is changing
the flow rate from the pitcher and how
that corresponds to building surface
tension in the cup. As we pour milk and
foam into the cup surface tension begins
to build, starting with very low surface
tension when the cup is empty and high
surface tension once the cup is full.
As a result the sooner you begin design the
more the design can flow across the cup.
The later you begin design the smaller
and more compressed it will be. To pour
large designs that fill the cup entirely
tilt the cup aggressively and bring the
pitcher down to the rim of the cup as
soon as the liquid reaches the rim.
Because you've begun the design when the
surface tension is relatively low, it
will allow it to flow across the cup
before the surface tension is high
enough to compress it. Now that we've
talked about the timing aspect of
surface tension, let's discuss the flow
rate aspect.  Because surface tension is
building as we fill the cup, it's
important to continue to increase the
rate of pour from the pitcher to keep
designs flowing. Begin designs with a
relatively low flow rate and continue to
pour faster as the design progresses to
keep the design flowing across the cup
and prevent foam from piling up at the
spout of the pitcher. Here is an example
of starting the design portion of a pour
as soon as possible after the fill
portion. Note how it affects the design
on the surface making it nice and big.
Now watch what happens when you fill for
longer and start the design later in the
pour. The design on the surface looks
small and compressed--like it never got a
chance to flow across the cup because we
began the design when the surface
tension was high. In each pour note how
the flow rate from the pitcher increases
steadily as a design progresses.
Now that we've talked about height and
the surface tension flow rate connection
the final core variable we have to
understand is the position of the
pitcher in the cup. To understand where
to place the pitcher, let's first talk
about how milk flows from the pitcher
and around the cup. Similar to blowing up
a balloon the design is going to form in
front of the pitcher traveling down
towards the bottom of the cup and then
circling back up and around. With that in
mind
imagine a crosshairs in the cup. The way
to pour a centered design is to place the
spout of the pitcher slightly above the
center, allowing the balloon to fill up
below the spout. If the spout is placed
in the center of the cup, the balloon
will fill toward the bottom leaving the
top half empty. If the spout of the
pitcher is placed towards the top of the
cup the foam will run towards the bottom
but won't circle back around, creating a
long shape instead of a nice circle. If
the spout is placed on either side of
the cup, it will create a current
carrying the design around and making
one side larger than the other. First
let's see what happens when you place
the spout of the pitcher too low in the
cup right in the center of the
crosshairs.
Note that the design fills at the bottom
of the cup leaving the top empty.
Next let's see what happens when the
spout is placed too high in the cup.
Note that the design runs out of energy
before it reaches the bottom of the cup
and is long and weird-looking instead of
nice and round. Now let's see what
happens when the pitcher is placed on
one side of the cup or the other.
Note the current that forms in a spiral
around the cup carrying the design with
it and making one side larger than the
other. To help with consistency while
you're learning, when you find a good
position take note of where the spout of
the pitcher rests on the rim of the cup. For the purpose of this design and other
round designs once the pitcher touches
the cup, maintain that position
throughout the design. Letting the
pitcher drag backwards across the cup as
you untilt will cause a stacked
triangular shape instead of keeping it
nice and round. So far in these examples
we've been pouring a traditional
cappuccino design referred to as a
monk's head. While a monk's head is
perfectly fine in its own right, let's
put a tail at the bottom to transform it
into a solid heart shape. To accomplish
this, start by forming a good solid
monk's head by following the steps we've
talked about so far. When the cup is
almost full, raise the pitcher back to
the three inch (7.6 cm) mark to stop actively
forming a design and slowly move the
stream of milk to the bottom of the cup,
drawing the monk's head to a point
forming the tail of the heart. When you
reach the bottom of the cup abruptly
stop pouring to finish the design.
This technique is referred to as the
draw through, and will finish most
common latte art designs. When performing
any draw through make sure to cross back
into the three inch mark or you'll drag
a line of foam through the design. Also
be careful to decrease your flow rate
and move slowly through the center of
the design to prevent from sinking the
design below the surface or dragging it
to the bottom of the cup. At this point
in the process we've learned to pour a
clearly recognizable sought-after a piece
of latte art: the solid heart. Congrats! It
is strongly advisable that you stop here
and perfect this design before moving on.
A good barista should have at least one
design they can pour reliably for
customers instead of pouring poorly
executed designs for them while they
practice. Now that we can consistently
pour a solid heart let's give it some
pizzazz and learn how to add texture or
ripples to a design. To add even layers
to a design, maintain a consistent flow
rate from the pitcher and add a very
slight back-and-forth motion with your
wrist. This will cause the milk to start
to swing in a pendulum motion inside the
pitcher. Note how even and consistent the
rocking motion is of the milk inside the
pitcher and how little the pitcher is
actually moving to accomplish this.
Because you're spreading the stream of
milk out over a wider area the actual
force of the milk is lessened so it's
important to keep your flow rate high
and not lose momentum as you pour the
design. The goal is to have a consistent
even pendulum motion from the milk in
the pitcher and avoid twitchiness by
keeping your flow rate consistent and
your motions even. Here we'll use a
consistent pendulum motion and even flow
rate to pour rippled heart. Do everything
we've done previously to pour a great
solid heart, but just add the pendulum
motion from the pitcher.
Here's what the same design looks like
when you're twitchy and inconsistent.
Honestly this isn't the worst heart
we've ever seen but it's definitely not
the consistent even rippled heart we poured
before, and this motion would be
disastrous for other designs, as we'll
see next. Now that we're comfortable
pouring different types of hearts, let's
use those skills to pour a more complex
design. This next one's called a tulip
because it resembles a cute cartoonish
flower coming out of the ground. This is
a great design for beginners because it
gives you the chance to start and stop
to correct any mistakes you've made
throughout the pour. Begin by pouring a
rippled heart shape in the center of the
cup just like we've been doing. This time
though, instead of drawing through the
bottom, stop pouring abruptly when the
top of the heart begins to take shape.
Next, place the spout of the pitcher just
above where the heart shape meets and
pour a solid heart shape into the
rippled base you just formed. If the cup
is full at this point simply lift the
pitcher up and draw through into the
base to finish the design. In this
example we still have some room in the
cup so we're going to add another layer
just like we did before by placing the
spout of the pitcher just above where
the base meets. After forming a solid
heart shape at the top of the design,
we're going to finish it off by
performing a draw through. The tulip
gives you a lot of options but as you
can stop and start as many times as you
want, adding as many layers as you have
room for. Also if you notice that your
design is getting off-center, you can
correct that to a certain extent by
placing your layers at different points
in the cup.
An important thing to keep in mind in
this design is that the milk in the cup
and in the pitcher is going to start to
separate if it sits for any appreciable
amount of time, so be sure to pause for
as little time as possible in between
layers so the foam remains fluid and
pourable. In latte art there are two main
shapes we can form, and how we combine
those shapes determines the design. Those
shapes are heart shapes and leaf shapes.
Heart shapes are formed by maintaining
your position in the cup as you pour or
pushing forward slightly, resulting in
the round shape we've been pouring so
far in this video. Leaf shapes on the
other hand are formed by pulling the
pitcher backwards as you pour causing
the lines to stack up instead of curling
around.
Let's employ this new technique to form
a design called a rosetta.
The rosetta is a much more difficult
design to pour because it involves a lot
of movement and doesn't give you much
time to assess and adjust mid pour. Don't
be frustrated if this design takes a
while to get down and remember not to
practice on customers. A great-looking
solid heart always looks better than a
rickety rosetta. We're going to start the
rosetta just like we started the rippled
heart and the tulip, by placing the
spouts of the pitcher just above the
center of the liquid in the cup and
rocking the pitcher side-to-side gently
to form a consistent even pendulum motion.
Just like in the tulip we're
watching for the top of the heart shape
to begin to form before we make a change.
This time though instead of stopping the
pour abruptly we're going to slowly move
the pitcher backwards towards the top of
the cup while keeping our flow rate
consistent and our pendulum motion even.
Make sure not to lessen your flow rate
or make any jerky motions with the
pitcher at this point as that will
result in twitchy looking uneven leaves.
When the spout of the pitcher reaches
the top of the cup, hold that position
until the cup is full to form a solid
heart shape.
Once the cup is full, gently perform a
draw through to knit the leaves together
pouring through the center to finish the
design. Now we've covered all the basic
techniques and shapes to pour great
latte art. Once you're comfortable with
everything we've covered so far, feel
free to get creative and combine these
designs and techniques in different ways.
Remember though that with great latte
art comes great responsibility, and when
you pour something gorgeous for a
customer you're promising them you've
done all the work up until that point to
make sure their drink is going to taste
just as good as it looks.
