2.6: I love chocolate but I don’t want to keep eating it, why?

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Из курса от партнера The Hong Kong University of Science and Technology

The Science of Gastronomy

195 оценки

The Hong Kong University of Science and Technology

The Science of Gastronomy

195 оценки

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

Из урока

Orientation, Module 1 and Module 2

This week, we will focus on “Energy Transfer” and “Hunger and Satiety”. Before you start with the content for these modules, please watch the Course Overview, review the Grading Scheme, and read the Important Note on special dietary needs.

2.0: Hunger and Satiety - Topic Outline1:39

2.1: Why do we need food?5:36

2.2: How do I know that I am full or not?9:38

2.3: How do I know that the food is good?9:52

2.4: Demonstration – Can you see the differences?3:52

2.5: Demonstration - Sound and texture - How does the experiment work?1:36

2.5: Demonstration - Sound and texture - Let's hear other people's views1:30

2.6: I love chocolate but I don’t want to keep eating it, why?8:46

Assignment 1 - Instruction Video3:22

Assignment 1 - Result Sharing5:08

2.7: What factors can affect my choice of food?17:02

Assignment 2 - Instruction Video3:40

Assignment 2 - Result Sharing7:16

2.8: Hunger and Satiety - Topic Summary2:05

Познакомьтесь с преподавателями

King L. Chow
Professor
Division of Life Science
Lam Lung Yeung
Associate Professor
Department of Chemistry

After learning about our, how our endocrine system and our nervous system

help us to perceive the quality of food. Let's look at a particular situation,

which is when we're stimulated by the same kind of food again and again, we

develop something that's called sensory-specific satiety.

Why do people develop such a sense when they are exposed to the same food again

and again, and again gradually they lost interest in eating it anymore?

Now, in fact, there have been different kind of hypotheses suggesting that how it

takes place. Some people would suggest that it's

because of the need of calories goes down.

when we're eating the same kind of food, we basically keep on gaining more

nutrients, and so therefore, we no longer need the nutrients for the energy, so

therefore, we don't like it as much. Sometimes we say that well, there are

other minerals, macronutrients that they are no long needed, so we develop this

sensory-specific satiety. But I think that from all the experiments

done in the past, what we learn is that there are two main factors.

One of the factors is related to the amount of the food, or the volume of the

food. The larger it is, in fact, you get

sensory-specific satiety very quickly. The next thing is because of the amount

of sensory stimulation. Think about that, if you are eating

something which is sweet, I constantly give you sweet food, again and again, and

again not necessarily, because of the amount, is because of the stimulation.

The repeated stimulation is going to generate some sort of like

desensitization. Then you lost interest in it, so

therefore, the focus is the following. The volume and the amount of stimulation

and the food. That is going to result in sensory

specific satiety. Now, we would ask how the consuming of

the one food would affect the pleasentness of the other.

And in fact, if you understand how the sensory specific satiety comes in to

places then certainly you would understand why sometimes when we're

eating something sweet. And then you eat something which is not

exactly the same food, but then if it's still sweet you've lost interest in that and

you don't want to eat that anymore. Because they have the same kind of

stimulation, and also sometimes we say that when the food will have the same

kind of texture. Lets say if they're very soft.

You constantly eat something that is very soft and very jello like again and again

and again. Over time we repeat this stimulation

results in sensory specific satiety. Now, that in fact is very important.

We ask, when we develop that, how this response, this hedonic response, is going

to be generated. We say that, well, can we simply

stimulate your sensory input with or without ingestion.

What are the two? Sensory input sometimes is coming from

the tongue, coming from the nose. But when you ingest sometime it's in your

throat so that's a different place being stimulated.

And sometimes when we learn about whether a food is good or bad, we also think

about what's behind the food. What's the knowledge about how the food

is being prepared. That again is stimulating a different

perception. And sometimes, of course, when we eat the

same thing again and again, I can't eliminate the possibility that because,

that we are no longer in demand of the energy or the nutrients.

So the interest or satisfaction that we would obtain is much less.

Now, we ask if that's the case, would there be any food which is, they taste so

good, they would be resistant to any sensory-specific satiety?

I guess, it's very unlikely, because we know that in all the sensory input that

we obtain. In fact, all the sensory receptors that

we were talking about a bit earlier, they were being stimulated, but then gradually

they become desensitized. So, what happen is that sometime some

food, if it tastes very good, it may take them a little bit longer to get

desensitized and you lost interest in them.

And some food, if they're not tasting very good, maybe they develop the sensory

specific satiety a little bit earlier. Now, having that in mind, it reminds you

of one thing. When you're preparing food, the most

important element of it, we want to generate variation of flavor.

We want to generation variation of shape of the food.

We want to generate variation of the texture of the food, the appearance, and

sometimes we want to use different material.

All this, essentially, is talking about when more of these properties are being

provided in the stimulations. We would have more satisfaction coming out

of it. It enhances the quality of food.

So what I mean is that there are two aspects.

One is physicologically. that means we have more of senory organ being stimulated at

the same time. At the same it has another element of it,

which is about the nutritional input. It is instinct, it built evolution,

that's why we want to have different texture at different taste.

Because different taste stands for they represent different kind of nutrient.

So more stimulation, that means we are capturing a lot of important type of

nutrients. So therefore, it is good, isn't it?

So that's what they say. This is a very important strategy for

survival, because having this variation of stimulation means that we will have

more energy intake, because there are more nutrients of different shape and

form and taste and smell they are coming to us.

So, we would able to maintain some sort of like a nutritional balance.

Now, take that into mind even though we are not really aiming for getting this

nutritional balance when we are preparing a meal, but then it help us to do the

meal planning. So take for an example using a famous

Chinese dish called Peking duck. We want to introduce idea that we want to

increase the so called contrast to have more ingredients that can stimulate our

sensory input. In this case, in the peking duck look at

what is in the peking duck. The peking duck is not just a duck.

What a Peking duck has is that we would have a duck.

Usually they are a little bit of fat so they need to have fat underneath the

skin, and they have meat. So, certainly and when they are roasted

like this they have a very specific color.

What other things do we add? We have the dough and it depends on

different restaurants. Some of the dough are much

softer or thicker some, some are harder and we have the, the, the onion,

sometimes we have cucumber and all this together with the sauce.

Now combined together, what do we do? When you eat them, you cut a piece of

this duck with the skin, together with the fat and some meat.

What do you do? You wrap them into the dough and you put

the crispy cucumber and you put the sauce.

What are you experiencing? It's something like this, and then you

eat them all in one mouth and put into your mouth

and you, what do you sense? You are sensing a variation of texture.

You are sensing a variation of temperature.

The duck is hot but the cucumber is cold and the taste

You have the taste of the sauce. You have the taste of the cucumber.

You have the taste of the meat. You have the taste of the skin, which is

crispy. At the same they have a different

texture. The cucumber is a bit crunchy, and the

fat, they would be very soft. the meat maybe a little bit tender.

So, at the same time, you combine all these in one single bite.

That gives you the maximum stimulation of the sensory input.

And that's why you find Peking duck is very tasty.

And in fact, in the following we can do experiment with our students and see

actually how they perceive this sensory specific satiety.

And that will tell us how come sometimes you don't want to eat certain food

and sometimes you want to eat more.

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