Food Science Basics Session 2: Food Chemistry Basics FoodCrumbles.com
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? • Ever wondered why your pancake batter rises and forms air bubbles when baked? • Never understood why your newly developed product changes color? FoodCrumbles.com 2
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/ FoodCrumbles.com 3
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! FoodCrumbles.com 4
Content 1. Atoms & Molecules 2. Drawing molecules 3. Main groups of molecules in food: macronutrients 4. Applying our knowlege FoodCrumbles.com 5
Atoms & Molecules - Atoms The basics • 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 A simplified illustration of an atom • Electrons have a negative charge Yellow = protons Red = neutrons Green = electrons FoodCrumbles.com 6
Atoms & Molecules - Atoms 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. Atom 1 Atom 2 Atom 3 Protons (+) = 10 Protons (+) = 10 Protons (+) = 10 Electrons (-) = 8 Electrons (-) = 10 Electrons (-) = 12 Charge = +2 Charge = 0 Charge = -2 FoodCrumbles.com 7
Atoms & Molecules – Atoms The most prevalent ones in food • 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 Atoms are food. abreviated • Oxygen (O): oxygen is particularly good in participating in all sorts of chemical by short letter codes 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 - Together these two form a • Calcium: Ca 2+ salt, the common salt you use in your kitchen! FoodCrumbles.com 8
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 (O 2 ) – the gas we breath from • Hydrogen (H 2 ) • 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). FoodCrumbles.com 9
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/ FoodCrumbles.com 10
Content 1. Atoms & Molecules 2. Drawing molecules 3. Main groups of molecules in food: macronutrients 4. Applying our knowlege FoodCrumbles.com 11
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! FoodCrumbles.com 12
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. FoodCrumbles.com 13
Drawing molecules • Here are three examples of molecules that can be formed: 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. • 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. FoodCrumbles.com 14
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. FoodCrumbles.com 15
Content 1. Atoms & Molecules 2. Drawing molecules 3. Main groups of molecules in food: macronutrients We will only touch upon them very briefly, for a more detailed description 4. Applying our knowlege go to the course website (https://foodcrumbles.teachable.com/ courses/food-science-basics) FoodCrumbles.com 16
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 out. They play a major role in browning reactions for example as well as flavour development and taste. FoodCrumbles.com 17
Macronutrients Carbohydrates • Carbohydrates are built from carbon, oxygen and hydrogen atoms. Most carbohydrates can be described by the following chemical formula: C x H 2y O y . In other words, the number of hydrogen atoms is twice that of oxygen. 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. FoodCrumbles.com 18
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