This is a traditional “alioli” recipe.
Traditional as we use to eat nowadays,
the real traditional “alioli” would be only with garlic and olive oil,
but here we are going to make a trap
and we'll add egg yolk.
this egg yolk is used
to put less garlic.
We take a garlic clove and
we take out the inside part
and put it into the mortar
For one egg yolk we’ll use two garlic cloves.
We open it
and it's ready.
It is important,
to put a little salt to the garlic
we put a bit of salt
we need to mash the garlic cloves until getting a paste.
We’ll take the egg
We’ll take the egg and
And this is a trick
see, we have the egg yolk inside.
We add the yolk here,
you didn’t know about this trick, did you?
and we add the egg yolk
and
We can start now
One of the tricks that will help is adding
a little hot water
a few drops of hot water when necessary.
We’ll start to whip the eggs.
A good virgin olive oil,
with low acidity, only 0’4 degrees of acidity,
here we have a Siurana, a catalan olive oil.
And we’ll start,
first we’ll start very slow
and after we’ll keep doing.
DAVID WEITZ: So an emulsion is drops of an immiscible fluid in a second fluid.
Drops of one fluid in a second fluid.
A foam is the same thing, except instead of using a fluid on the inside
of the drops, you use air, a gas.
So how do you make an emulsion?
Well, the best way I can show you is to do it with this little experiment.
Here I have olive oil and water, and I'm going to try to mix them together.
And olive oil is not miscible in water.
And when I pour the olive oil onto the water, it floats on top.
It's lighter than the water.
So the only way I can mix them is to shake them.
So let me shake them like this.
And look, they do mix, but they don't completely mix.
Instead, you form drops of the oil in the water.
And that's an emulsion.
But let's watch this for a little while.
We put it on the side, and remember.
The oil is lighter than the water, and it's
going to start to float to the top.
And as it floats, the drops become closer and closer.
And they begin to join together.
And they lose their stability.
The emulsion doesn't remain drops of one fluid
in another but rather phase separates.
Becomes the two fluids again.
And if you look at them, if we watch them over time,
you'd see they completely phase separate.
So this emulsion is not stable.
So how do we make an emulsion?
An emulsion is mixture of one fluid in a second by making drops.
For example, in this case, we've made oil drops in water.
The oil drops are now called the dispersed phase.
The water is called the continuous phase.
And to make an emulsion, you have to mix them together.
Somehow you have to form drops of the dispersed phase
in the continuous phase.
And when you do that, you get these drops, and that's your emulsion.
But to make them stable, you have to prevent the drops,
or you have to keep the drops as individual drops.
You can't allow them to join together or coalesce.
Somehow you have to stabilize the interface
of the drops of the oil in the water.
And we do that using a surfactant.
A surfactant is a surface active molecule.
It's an amphophilic molecule.
Part of it is water-like, or hydrophilic,
and the other part is oil-like, or hydrophobic.
And they're joined together.
So the surfactant molecules like both the oil and the water,
and they can't really decide which they want.
So they can't really sit in either the oil or the water.
Instead, they prefer to sit at the interface,
at the surface between the two fluids.
Typically, you put the surfactant in the continuous phase.
So if you have an oil in water emulsion, you put the surfactant in the water.
So part of the surfactant sits at the oil.
There's excess surfactant, however.
You need to have excess surfactant so that you always have more
surfactant available, so that it can come to the interface
as you create the interface when you're emulsifying something.
The surfactant has to come out of the water and go to the interface.
However, the surfactant does not like to stay in the water,
because it has part of it which is oil-like.
It doesn't like to be in water.
So instead, the surfactant forms aggregates.
We call these micelles.
The aggregate, so that the tail groups, the oil part of the surfactants
are all connected together.
They're all facing one another, excluding some of the water.
That allow the surfactant to exist in the water
without exposing the tail groups to the water itself.
But the micelles act as a reservoir.
They can easily break up and bring new surfactant to the interface
as you create the interface.
And if you have enough surfactant--
an egg yolk, for example, is an excellent surfactant-- they completely
coat all the interfaces.
And then when drops come together, as I show here
in this little cartoon, when two drops come together with a coated interface,
with a surfactant-covered interface, it prevents the drops
from joining together and becoming larger drops.
So the drops remain stable, and the emulsion remains stable.