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Any and all food is made up of countless different molecules. Whether it’s the molecules that give cinnamon its distinctive taste, or those that color your orange, yes, orange. There simply are too many to count, and studying them may seem daunting.
Molecules may have complex names, such as cinnamaldehyde, or β-carotene, ascorbic acid, or saccharose. This doesn’t always make it easier to understand what they do. To more effectively study these building blocks, we can use chemical formulas. These simple formulas make it easy to describe and compare the molecules that make up food.
Molecules are made up of atoms (elements)
Molecules are chemical structures that are made up of even smaller building blocks: atoms. You could compare it with Legos: an atom is a single lego brick, whereas a molecule is the structure that is made from putting several bricks (at least two) together.
Molecules can be small, made up of as little as two atoms. But food also contains plenty of molecules that are made up of hundreds, if not more, atoms connected together.
Select number of elements available
On this world, there are a little over 100 different atoms or elements as they are referred to. All known elements fit on the periodic table. If you’ve ever taken a chemistry class, you’ve likely encountered the periodic table at some point in time. In food, only a small group of elements make up the vast majority of ‘building blocks’ in food’s molecules:
- hydrogen (H)
- carbon (C)
- oxygen (O)
- nitrogen (N)
The letters given behind each element are the abbreviations used to signify that element. Every element has such an abbreviation. Most abbreviations are only one or two letters long. Some other examples commonly found in food are:
- sodium (Na)
- chloride (Cl)
- phosphorus (P)
- calcium (Ca)
Chemical formulas in food
To start comparing different molecules in food, it is important to know what elements they are made of. This is where chemical formulas come into play. Each molecule can be expressed by such a formula* and it will tell you exactly which elements it is made of. A chemical formula is the ‘ingredient list’ of your molecule.
To write up a chemical formula, a chemist will first evaluate which elements are present. Next, they will count how many of each are present. The abbreviations of each element are listed next to each other and using a number as a subscript, the number of one such element in a molecule is given.
Let’s look at a few examples:
- Water, one of the most common ingredients in food!
- A water molecule is made up of 2 hydrogen atoms (H) and 1 oxygen atom (O)
- Chemical formula for water: H2O
- Ascorbic acid (another name for vitamin C)
- Made up of 6 carbon atoms (C), 8 hydrogen atoms (H) and 6 oxygen atoms (O)
- Chemical formula: C6H8O6
- β-carotene (responsible for the colour in carrots)
- Made up of 40 C-atoms and 56 hydrogen atoms
- Chemical formula: C40H56
Chemical formulas quickly provide an idea of the type of molecule that a food is made up of. As such, it can help you classify and group molecules with a similar structure. This is helpful since molecules with similar structures often have certain properties in common. For instance, they might contribute to flavors, participate in certain chemical reactions, or melt at a certain temperature.
A good example of this is a group of molecules called carbohydrates. The molecules listed below are all carbohydrates. Their chemical formulas are very similar.
- Glucose – C6H12O6
- Sucrose (standard sugar) – C12H22O11
- Lactose – C12H22O11
- Starch (part of flour): (C6H10O5)n (the n indicates it can be a long chain of these groups of molecules)
Don’t tell the full story
In the list of carbohydrates you may have also noticed a downside of using just chemical formulas to describe molecules. They don’t tell the full story.
Sucrose and lactose have the same chemical formula. But, they aren’t the same molecules. The individual atoms are connected in a different way in both molecules, resulting in a different structure. In other words, a chemical formula only contains the list of ingredients. But, it misses the ‘instructions’ of a recipe.
In those cases, chemists will use structural formulas.
Adding some extra detail
In some molecules, how certain groups of atoms are connected is crucial for how they behave. Those specific groups may determine whether a molecule will react under certain conditions for instance. In those cases, the chemical formula may be written a little differently to highlight that specific group. This is a way to overcome the lack of structural knowledge of a molecule.
Two common groups in food that you may come across are -COOH and -NH2. The first, -COOH also called a carboxylic acid, is an acid. The later, -NH3, is an amino group and crucial in proteins.
Some examples of how this may look like:
- Acetic acid (makes vinegar acidic):
- C2H4O2 – the standard way
- CH3COOH – this tells you a little more about how it’s put together
- Glycine (a basic amino acid, a core building block of proteins)
- NH2‐CH2‐COOH – it clearly shows those two crucial groups
- Linoleic acid (a fatty acid, a component of many fats & oils)
Too big to write down
Some large molecules such as starch can still have quite a simple chemical formula. However, there are also large molecules that are too large and complex to write down in this manner. In those cases a chemical formula is no longer a useful tool. In food, most proteins are too complex to write down in this manner.
The starting point of food chemistry
Of course, chemical formulas are just the beginning! Just about every food is made up of a lot of different molecules, with each its own chemical formula. Up next is understanding how these molecules, interact and impact your food. All of that is exactly what food chemists do day in day out.
Understanding and knowing chemical formulas is the starting point for understanding the chemistry of your food. A lot of chemistry starts with just knowing what you’re food is made of. Chemical formulas help you understand what carbohydrates, fats and proteins truly are. They’ll help you understand the science behind flavor, and much more.
To truly dig into this field, why not consider taking our food chemistry class?