Food Science Basics Session 2: Food Chemistry Basics - - PowerPoint PPT Presentation

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Food Science Basics

Session 2: Food Chemistry Basics

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Ready, to immerse yourself in the world of food science?

• Ever wondered why bananas turn brown?
• Never sure which microorganisms in food can be harmful?
• Ever wondered why your chocolate mousse stays light and

fluffy?

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• Ever wondered why your pancake batter rises

and forms air bubbles when baked?

• Never understood why your newly developed

product changes color?

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Week 2

• This deck is part of a 6 week course on the basics of food science,

discussing all of these topics!

• It’s a course for, amongst others:
• Food Professionals
• Food Bloggers
• Chefs
• (High school) students
• Besides food chemistry (this week’s topic) we’ll be discussing: food

physics, food microbiology and some food packaging!

• Want to take the complete course? Sign up at:

https://foodcrumbles.teachable.com/courses/food-science-basics/

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Let’s get going!

This week’s content will be focussing on the basics of food chemistry. To do that we’ll be:

• Discussing atoms & molecules; atoms form the building blocks of

molecules and molecules in food are the important thing to study when looking into food chemistry

• Drawing molecules; this might sound strange, but the way atoms

form a molecule is so important that it’s essential you know how to ‘read’ drawings of molecules

• Discussing carbohydrates, fats & proteins; some of the most

important and common molecules in food, not only from a dietary perspective, but also from a chemical one!

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Content

• 1. Atoms & Molecules
• 2. Drawing molecules
• 3. Main groups of molecules in food: macronutrients
• 4. Applying our knowlege

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Atoms & Molecules - Atoms

• Atoms are the building blocks of our food. There are a lot of different
• atoms. Chemists found a very convenient way to sort and represent

them: the periodic system.

• Hint: search for Tom Lehrer’s “The Elements” on YouTube for a great song on the

periodic system.

• You can visualize atoms as little ‘planets’, the center is made of

protons & neutrons, around which electrons float.

• The exact build is not of importance for food.
• But the concept of protons and electrons is important to grasp,

important to know is that:

• Protons have a positive charge
• Electrons have a negative charge

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The basics

A simplified illustration of an atom Yellow = protons Red = neutrons Green = electrons

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Atoms & Molecules - Atoms

Atom 1 Protons (+) = 10 Electrons (-) = 8 Charge = +2 Atom 2 Protons (+) = 10 Electrons (-) = 10 Charge = 0 Atom 3 Protons (+) = 10 Electrons (-) = 12 Charge = -2

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Protons & electrons cause charges

Atoms can have a charge, once their charge isn’t neutral (zero) it is called an ion. Ions are pretty important in chemistry and food.

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Atoms & Molecules – Atoms

• Now that we know ions and atoms, let’s present to you some of the most

important atoms in food!

• Carbon (C): this is the building block of most of the molecules we'll come across in

food.

• Oxygen (O): oxygen is particularly good in participating in all sorts of chemical

reactions.

• Nitrogen (N): this atom is essential for making proteins.
• Hydrogen (H): is probably the most prevalent atom, however, often 'fills up' empty

spaces in molecules.

• Phosphorus (P) & Sulfur (S): often play an interesting role in protein chemistry.
• Some important examples of ions in food are:
• Sodium: Na+
• Chloride: Cl-
• Calcium: Ca2+

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The most prevalent ones in food

Together these two form a salt, the common salt you use in your kitchen!

Atoms are abreviated by short letter codes

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Atoms & Molecules - Molecules

• Let’s make the next step into molecules! Atoms can react together to

form a molecule. Molecules are larger structures of atoms which have reacted with one another to form a structure.

• The simplest molecules are those made up of only two atoms, for example:
• Oxygen (O2) – the gas we breath from
• Hydrogen (H2)
• Since molecules are build from atoms, we can use those letter codes

to represent the molecules!

• This is done by showing the letters of the atoms they are built from and a

small subscript number to indicate how many of this atom are present in the molecule (as I did for the oxygen and hydrogen molecules).

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Atoms & Molecules - Molecules

• Assignment 1: Read this separate post about these formulas to help

you understand them, using several examples.

• If the link doesn’t work, go here: http://foodcrumbles.com/chemical-

formulas-food/

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Content

• 1. Atoms & Molecules
• 2. Drawing molecules
• 3. Main groups of molecules in food: macronutrients
• 4. Applying our knowlege

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Drawing molecules

• Now, imagine a molecules made up of 4 carbon atoms, 2 oxygen

atoms and a bunch of hydrogen atoms. They can be connecte to one another in a lot of different ways!

• For a chemist it is very important to know how these atoms are

connected together. This strongly influences what they do, how they react, etc.

• Did you know? Molecules can have the same molecular formula, but be two

completely different tasting/smelling molecules because of how their atoms are linked to one another!

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Drawing molecules

• This is why we need to know how the structure of molecules can be

represented!

• It would be far too much to discuss all the aspects of atoms bonding and
• reacting. Instead we'll focus on the basics again, more specifically on the 4

most prevalent atoms:

• Carbon is great at forming large complex structures. One of the reasons is that one

carbon atom can attach itself to up to 4 other atoms. It can form four so called

• bonds. These bonds can each be attached to a different atom, but it is also possible

that several bonds attach the carbon to the same atom!

• Oxygen on the other hand only has two bonds available. Nitrogen has three

and hydrogen has only one bond possibility.

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Drawing molecules

• Here are three examples of molecules that can be formed:
• What might be confusing is that chemists are a little lazy. Since there tend

to be a lot of carbon and hydrogen atoms, they are often left out. So wherever you see a split of bonds, that's where a carbon atom sits.

• Since hydrogen atoms form just one bond they tend to fill up the empty

spaces on a molecule and aren’t even drawn. All empty spots are hydrogens, but those at the end of molecules are often drawn again.

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A carbon atom with two bonds extending to its neighbour carbon atoms and with two, not rawn, hydrogen atoms to fill up the two vacant spaces.

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Drawing molecules

• Drawing molecules is essential when they start becoming larger as

there's no way to see by the chemical formula how the atoms are attached to one another.

• For even larger molecules (for a lot of proteins this is the case), the

molecules become so large and complex that even structural formulas aren't useful anymore. Other ways of representation have to be used in those cases.

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Content

• 1. Atoms & Molecules
• 2. Drawing molecules
• 3. Main groups of molecules in food: macronutrients
• 4. Applying our knowlege

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We will only touch upon them very briefly, for a more detailed description go to the course website (https://foodcrumbles.teachable.com/ courses/food-science-basics)

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Macronutrients

The three main groups of molecules in food are:

• carbohydrates,
• proteins,
• fats.

These molecules are also called 'macronutrients', they are essential for us from a nutritional point of view. The three groups of molecules have very distinct characteristics that will influence how your food will turn

• ut. They play a major role in browning reactions for example as well as

flavour development and taste.

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Macronutrients

• Carbohydrates are built from carbon, oxygen and hydrogen atoms. Most carbohydrates can be described by

the following chemical formula: CxH2yOy. In other words, the number of hydrogen atoms is twice that of

• xygen. The number of carbon atoms does not have to be related to the number of oxygen and hydrogen
• atoms. (Note, there are a few exceptions to this rule!)

Carbohydrates are also called saccharides. It a different name, for the same group of molecules. When talking about saccharides they are often split up into four groups:

• 1. Monosaccharides: the smallest carbohydrates made up of only one ring. Glucose and fructose are probably

the most well known monosaccharides.

• 2. Disaccharides: are always built from 2 monosaccarchides. For instance, lactose is made from glucose and
• galactose. Sucrose (regular table sugar) is made from fructose and glucose.
• 3. Oligosaccharides: made from more than 2 monosaccharides, generally 3 to 10. These molecules can often

be found in plants, giving them structure.

• 4. Polysaccharides: huge molecules made up of more than 10 monosaccharides. They can form complex
• structures. A common example of a polysaccharide in food is starch.

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Carbohydrates

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Macronutrients

• Proteins are another distinct groups of molecules. Unlike

carbohydrates, there isn't a distinction based on size. There are loads

• f different proteins and they all tend to be huge and highly complex.
• All proteins are made from amino acids:
• There are currently 23 known different amino acids (each with a different R-

group in the drawing) which, when combined, can create all proteins.

• Amino acids form proteins by forming one long strand. The OH-group will

react with the NH2 group, releasing a water molecule and forming a bond between the two amino acids.

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Proteins

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Macronutrients

• Unlike carbohydrates amino acids will not form complex networks. Each

protein is one long chain of amino acids.

• Amino acids along the chain can interact with one another! There are a lot
• f different interactions that can occur. These interactions can cause the

strands to fold up, or twirl around into all sorts of three dimensional structures and these again will organize themselves in a specific way.

• The shape of a protein is determined by how this long strand of amino

acids folds and turns itself and is essential in its activity!

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Proteins

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Macronutrients

• Fats belong to a larger group of molecules which are called lipids, fats

are a specific subgroup of lipids. All lipids are hydrophobic molecules (they don't like water).

• The chemically correct description for fats is: triglycerides. The name triglyceride describes

the basic structure of fats: one glycerol molecule, with three fatty acids attached to it (see below).

• There are a lot of different fatty acids (see right) and

those again can be combined in a lot of different ways to form different triglycerides.

Note, the kink in palmitoleic acid should all go down instead of bending horizontal again, for clarity purposes it was made horizontal agani.

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Fats

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Content

• 1. Atoms & Molecules
• 2. Drawing molecules
• 3. Main groups of molecules in food: macronutrients
• 4. Applying our knowlege

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Applying our knowledge

• This has all been quite theoretical, unfortunately, if you're new to the

topic, that's what you'll need to understand the phenomena you see in your food. But now it's time to see some knowledge come to life!

• Learn more about a common chemical reaction that can occur in
• il: oxidation.
• Have closer look at milk and butter discover the role of proteins and fats in

these delicious products.

• Learn what proteins can do when it comes to browning of fruit.
• Gluten are probably one of the most well-known types of proteins, learn

more about their role here

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Lik iked what you saw? Head over to: https://foodcrumbles.teachable. com for more courses Or http://foodcrumbles.com for more related blog posts!