This course introduces a number of basic scientific principles underpinning the methodology of cooking, food preparation and the enjoyment of food. All topics covered have a strong basis in biology, chemistry, and physics application. Among others, they include the consumption of cooked food, the physiological and evolutionary implication of the senses, geographic and cultural influences on food, and the rationale behind food preparation. We will also discuss issues such as coupling of senses to improve sense stimulation; altering flavor by chemical means; and modification of the coloration to improve the appearance of dishes. Following the video demonstrations of the scientific principles of cooking, you will learn to recognize the key ingredients and their combinations for preparing good healthy food. At the end of this course, you will be able to: - appreciate the scientific basis of various recipes; - develop your own recipes by integrating some of the scientific principles into new dishes; - recognize the influence of the material world on human perception from the different senses; - appreciate the art of integrating science into cooking and dining. Important Note: This course is not designed for people with special dietary needs such as vegetarian, diabetic, and gluten-free diets. If you feel uncomfortable with any part of the assignments or activities of this course, you can substitute some of the ingredients or ask friends and family members to help with the tasting of your assignments. Alternatively, you may skip that specific assignment provided that you have fulfilled all other qualifying requirement to pass the course. Course Overview video: https://youtu.be/H5vlaR0_X2I
5.3: Why the pepper doesn’t look good?
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Del curso dictado por The Hong Kong University of Science and Technology
The Science of Gastronomy
199 calificaciones
De la lección
Module 5 and Module 6
This week, we will talk about how color and texture of food affects our perception of taste of food.
Conoce a los instructores
King L. ChowProfessor
Division of Life Science
Lam Lung YeungAssociate Professor
Department of Chemistry
Well, after knowing how our eyes perceive light and
how they're being processed let's look at what color it is that we can generate.
Now so the color of the object that in fact we see, lets focus on it,
it is not really that the particular object is giving off the light or
giving a particular color that we perceive,
it's because they reflect the color that comes from our external source.
Now, in this case what we say is that when we see things in fact they are two
principle that we need to follow.
A lot of the color in fact they are based on the additive effect
of the colors that they mix together that allows us to see them.
The second one is about the subtractive color mixing, so
that we will be able to generate all varieties of color.
Let's look at how this is generated.
The first one is about additive color mixing, what essentially we are focusing
on is that these are the colors generated by light.
In this case as here.
We start without any light and we shine on it, we have three primary color light.
This is the blue, the green and the red and by the combination of that,
adding them together.
If you have the green light plus the blue light, you are going to generate cyan and
when you have the green light together with red it's going to generate yellow.
And when you have the blue and
red combined together, you're going to generate magenta.
And when you have all three together, you'll be able to generate white.
Basically, that's the full spectrum, all the light are being perceived.
Now that's additive.
On the other hand, that's also the subtractive color mixing.
In this case what we have is you can think of that as that you have
all the lights shining onto your eye, white as the background, and
what you do is you put on top of it so
that you filter out some of the light and only some light can come to you.
So, what will the filter be and these filters will be the cyan,
yellow and magenta.
Now if you go back to the additive effect think about that,
if you have a filter which is yellow what does that mean?
When as yellow, well it means is that you put out all the blue,
all right and when you have a cyan filter,
what I mean is that the light will pass through, what do you filter out?
What you begin to filter out is the red and the same for the magenta.
What you filter out is the green.
So what happen is that now you have these three primary filters, yellow,
cyan and magenta.
When you combine together, the light comes in, think about it,
when you used yellow as a filter, it takes out the blue.
And when you have the cyan filter it also takes out the blue.
Which one did they not take out?
It is only the green.
So in this case what you see is that when these two filter combine together,
they would be able to take out all the red,
and it would take out all the blue, and what's remaining is the green.
So the same applies to combining the yellow filter, and the magenta filter,
what's left out is only the red.
When you combine a cyan filter, and a magenta filter,
what's left out is only the blue.
Now that's about filter.
How about in the third situation?
This is the case that when we see most of the objects
what we see is that in fact the light shine onto some pigmented objects.
And these objects, they absorb all the light and they reflect only one.
So in this case when we see something which is red essentially
what I mean is that it absorbs all the light of the green range as
well as the blue range and it only reflects red.
Green, it absorbs red and blue and it reflects only green.
And this one, when it's blue, it absorbs all the red and green and
reflects only blue.
So, what happens is that, well if you have these pigments mixed together,
you will find that all the mixture essentially gives them a much darker color
because they have absorbed most of the light.
So, if all three of them combined together essentially what it means is that
they have absolved all the blue, all the green and all the red and
you'll have total darkness in the middle.
So that's how this pigment, that when you use the subtractive color mixing,
you'll be generating different kind of color.
Now, so to take you through, in a very simple way, we can use some
sort of like a formula like this to allow us to understand how color is generated.
For example, if you use white lighting and
you want to shine it onto a surface that absorb blue light, think about what it is.
White light would have red, green, and blue.
And what you do is you shine on a surface that absorb only the blue,
so you take away the blue.
So what's remaining?
Remaining is just the red and the green.
And red and green combined together, what's the color?
Yellow, right?
So that's very simple.
Let's do it again.
We can shine cyan light onto surface that absorb blue, so what it is?
Cyan actually is generated by green and blue together.
And, you take out the blue, so what happens this time?
The remaining part is the green.
So, these examples demonstrates that the color of something,
they do not necessarily come from what that object's color is, but
really, what they reflect and what is left and what is reflected to your eye.
Now for simple terms we can also think about other combinations,
we say that well, if you use white light essentially
the white light shine on anything that it would go onto these objects and
this object whatever paint color they are they would be preserved.
So essentially what it is so if you shine white light onto an object which is cyan
in color what it mean is that it's going to reflect both the green and the blue.
So as a result you see cyan.
In opposite we say that if you have a white surface
which is essentially reflecting whatever light that shine on it.
If you shine magenta light on a white object what it does it that well,
the white light would have the red and blue and you reflect everything out of it.
So what you get is that at the end you would have the red and
blue light being reflected and what you get is magenta.
For the same token, a very important element will come.
That is when you have all this light and paint, when they are mixed in certain way,
sometimes nothing comes out of it and as a result, you get totally black.
What would it be?
For example you can shine green light onto something,
which is magenta, a paint which is magenta.
Think about that, the light shined on it is green, what's magenta?
Magenta is reflecting blue and red.
But you shined only green light on it, so
what is it going to be reflected out of it?
Nothing, nothing comes out of it, of course it's black.
The same thing is that you can shine red light onto blue paint,
what you have the red light in, but
then the blue paint essentially it take away all the green and red.
So you take away the red, nothing comes out.
So when the light is not matching what is being reflected by the objects,
then you got totally black.
So let me try to demonstrate the effect to you.
I'm going to show you two objects.
One is a red pepper, the other one is a green cucumber and
you can clearly see that they are red and green in color under this white light.
No problem with that.
Now I'm going to show you these two object under a difference color
of light and see actually what you're going to see.
So may I have the light off?
Now, so here is what it is.
Let's look at the red pepper.
So here you go, this is the red pepper.
So do you see any color?
This is under the blue light.
How about the next?
It is a red pepper under the green light.
Do you see anything?
Think about that, the blue light and the green light, they shine on it.
This is a red subject which is absorbing both the blue and the green and
it is not reflecting anything out of it so therefore it appears black.
How about the next one?
We have now got the red light and with the red light on it, what's the subject?
A red pepper.
It reflects the red so therefore you can clearly see the red color.
How about the next?
Here you have the cyan.
So what you have the cyan is the green and blue.
Again, what do you see?
The next yellow.
Yellow is the light coming in where both the yellow and red.
So the green and red combine together.
The green will be absorbed and the red will be reflected by the pepper.
So therefore, under the yellow light you will see the red color.
How about the next?
Magenta, blue and red come in, blue absorbed and the red is reflected.
So clearly, you can see that under what kind of light,
you'll be able to see the real color of this object.
Now how about the green cucumber?
So, it is under the blue light.
Do you see anything?
What color is it?
Next, how about under the green light.
Very clear.
The green cucumber shows up.
How do the next one?
Under red color, red light in, they are all absorbed.
And this object is not reflecting any red light out so therefore you get black.
How about the next?
And magenta, so what you have is, you have the red and
the blue It goes in, it's never reflected.
Next, how about yellow?
Yellow is a combination of red and green.
The red has been absorbed and the green is reflected.
How about the next?
Now we have cyan.
Cyan is blue and green.
The blue is absorbed and greens show up, and it reflects the color.
So certainly in this demonstration you can clearly see that with different kind of
light, we'll able to see something.
May I have the light on?
Now, what I've demonstrated to you is a very important element that when you're
preparing a dish to be served.
We want the dish to be presented with a very colorful setting so
that it is appealing, and if you're using the wrong lighting and
you present the dish where a certain color
when the color is not being reflected what it turns out it's totally black.
So no wonder why in the restaurant sometimes they want to
use a certain color tone of their lighting.
It will give you the best presentation of the dish so that it's so
appealing that in fact you're going to order more and eat more.
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