On the other hand, when we talk about osmosis, usually we're dealing with
something called a semi-permeable membrane.
Now, so what it is, you think about that, is that if this one is a cell.
And this cell has a lipid-based membrane, which is here, marked in green.
So, what you have is is that molecules need to move from one place to the other.
But this so-called semi-permeable membrane will not allow some of the big
molecules to go from one side to the other.
So in this case all this red spots represent the big molecules.
So what we have is that, well, with this semi-permeable membrane.
On this side you have a lot of this big molecule.
They can go anywhere. But on the other hand, on the other side,
you have a lot more water, with less big molecules.
So in this particular membrane, they would be able to do is to allow the water
to move from the side, which is having lower concentration, into the side which
have higher concentration. And at the end when it reaches that a
point that both sides essentially will have a similar concentration.
And in fact this concentration some how is related to a concept called osmo
pressure. That makes these two sides essentially
have the same osmo pressure. Then they will then they will stop Now,
that have a consequence. Because, it that's the case, as
illustrated in this diagram in this animation.
What you have is this, all this water's molecules.
Small one, they will essentially go all into this side which has high
concentration of this big molecules. So what happen is that, if this big
molecule has a cell wall around them, that means they can't go in any more and
they can't go in any more. And they keep on trying to go in, so it's
pushing them to make them very rigid and very swelled up.
And so that's what happened on this side. The thing about that, if on this side all
the water goes away. And if there is a soluble there and what
would happen all the water goes away and the cell wall still there as a richer
thing. So basically you don't have any water
there to support it so it's kind of become a little bit collapsing yet was
the cell was still there. So what will be the net outcome is that
with this osmosis. these movement of water to one region
from the other region results in generating some cells, which they will
have a very swollen property. They are very rigid, they are very firm
or versus the other side that when water is taken out these cells would become
flaccid, they are very soft. Now, having that it has an effect on the
plant cell, but how about in case of the animal cell?
Animal cell they don't have the cell wall, so if all this water rush into the
animal cell. And this is just a lipid membrane, lipid
membrane is not very strong so what happen is that the animal cell is going
to burst. Alright?
On the other hand, if this is animal cell, you draw away all the water out of
it. So what you have is that animal cell is
going to shrink. So again, it is going to result in a
shrunken cell versus a cell that burst. In both cases the texture is a collective
integration of all the cells with such a property.
The texture will have been changed. Now, so think about that.
How salt can effect the food. Take for examples like that, when we have
prawns we have fish or chicken or sometimes when we put them in a lightly
salted water. Now lightly salted water, that means
there would be more salt outside than inside.
So, what happen is that the water is going to come out a little bit, but then
they don't come out all the way. So, what I mean is that a little some of
the water will be drawn out, and in such a case, for example for the prawn over
the fish. When you cook them, because the water has
been drawn out so that means the protein content inside all the cells are a little
bit higher. So when you cook them, when they put in
rice and the high heat by the nitration. So they would be able to form some
crunchy crumbs of this meat. the same thing when you have the
vegetable again. When you take a little bit out of the
water out of it. These will be still able to regain this
crispiness of the vegetable. But think about that, if I reverse it,
instead of using this so called slightly sautéed water, I'm simply putting down
into tap water. What would happen?
Thing about that, these prawns, if these are the prawns collected by the sea, they
get used to a high salt concentration. So that they have a little
bit more salt inside and outside. And you put in the tap water without any
salt. So what's going to happen?
These prawns would draw in all the water from the outside.
And with what it goes in, remember, these are animal salts.
So when water keep on going and going, the salts will keep on expanding and
expanding. When they reach a certain point, they
simply burst. So what happens is that if you leave them
there in the, well, tap water washing for too long, a lot of these animal salts,
they get to burst. And at the end, what I mean, is that,
they are no longer well organized. And so therefore, these, the, the prawns
turns into a lipid, mushy. And we don't like that, because we want
it to be crunchy. But at the same time, when
some other meat such as, for example, pork, or, beef.
when you have the water drawn into it. What happened?
If some of the, the salts are burst, since pork and beef, they are already a
little bit quite, tough, by, by itself in nature.
So bursting a few of those salts in fact can make them a little bit more tender.
Now, so. You need to play around with that and
decide actually how you want to use this osmosis property to change the quality or
the texture of all this food. Now the same thing that when we apply
that to the plant if the water goes in, it just makes the plant more rigid and
they are much firmer. Now having all of this I need to remind
you again this basically when we looked at any food, we look at the texture.
We use our eyes to look at the color, how they shine how, how grainy they are and
we look at whether they form lumps and whether they are heterogeneous.
And all this is telling us about the texture of the food.
And, more than that in fact, human being we will be able to do a lot of other
things. We want to maximize the contrast.
So what do you do? We can use a chopping board.
We can chop them into pieces. we can stir them.
we can cut them into different shape. In fact, why are we doing it?
We are simply trying to maximize the texture, shape, lumber, and all this
contrast, so that we would be able to enjoy the quality of it.
So, when goes into our mouth, we are perceiving the temperature, we are
monitoring actually what the size they are.
As I said, our tongue is very sensitive. It can tell the very detailed of all the
things that we take into our mouth. The dentition using all this, sensation
of the pressure biting on something. When we swallow, we're also using our
throat to sense, actually, what kind of quality it is.
And all this, when we are trying to masticate all the food inside our mouth.
We are also allowing some chemical reaction to go on because in our saliva
we are constantly digesting some of this food.
So therefore, the composition is constantly changing, maximizing the
contrast. So as a result with all of this
digestion. You may see that, for example, for some
of the food such as the case of a starch, they re-digest it and therefore it would
change in their viscosity. And all this combined together, it
generate variation and the same thing is that when we eat something in our mouth,
our saliva also provide a kind of lubrication.
So changing from very dry to be very lubricated.
And if something carries for example tendon they will provide the
that change the kind of quality of the graininess, of the toughness or
bitterness of all this food. It makes us feel very satisfying because
we are constantly stimulating our oral cavity.
Now, think about that, I come back to the same idea again.
