Food chemistry basics – Chemical formulas in food

Ever wondered which molecules make your bread turn brown? Or what molecules might sit in a pear? If you’ve ever thought about nutrition you probably did, since nutrition studies certain molecules in our food. In other cases you might have never realized you did, but any time you’re wondering why a certain reaction happens during cooking or food production, you probably did think something similar. Welcome to the world of food chemistry.

Food chemistry is one of those main disciplines within food science and it so happens that one of the most important aspects of food chemistry are the molecules in our food. And in order to study molecules you have to be able to know what they’re made of.

In another food chemistry basics post we introduced to you the concept of atoms and molecules. If the word ‘molecule’ or ‘atom’ makes you confused at the moment, it’s probably best to read that one first. In that post we very briefly covered how molecules are made and represented. However, by far not enough to actually start working with it. Therefore, this post will dive a little deeper and introduce the concept of ‘chemical formulas’ to represent the molecules in our food.

What again is food chemistry?

Food chemistry is all about studying molecules in food and their reactions. So, to study chemistry properly, you should at least know how to represent and write out those molecules. And that’s why we’re discussing chemical formulas today.

All of our food is build up of a lot of molecules. These molecules are again made up of atoms at least two of them, but most are made up of a lot more atoms, especially molecules common in food. There are a huge number of different molecules in food, each of them is a different combination of atoms. The most common atoms in food are hydrogen (H), carbon (C), oxygen (O) and nitrogen (N).

Each atom has its own abbreviation and for this post that abbreviation is what we’ll be looking at mostly, since it is used extensively to represent the structures of molecules.

Chemical formulas in food

Chemical formulas are in essence the ingredient list of a recipe, instead, it’s the ‘list’ of atoms that sit in a molecule. Chemical formulas can be used to describe which atoms sit in a molecule and how many. However, it does not tell you how they are connected. Linking it back to that recipe link, it show the ingredient list, but not how the ingredients can be made into a well tasting recipe.

Let’s look at a few examples:

  • Water, the water molecule is made up of 2 hydrogen atoms (H) and 1 oxygen atom (O), the chemical formula for water is: H2O
  • Ascorbic acid (another name for vitamin C) is made up of  6 carbon atoms (C), 8 hydrogen atoms (H) and 6 oxygen atoms (O), that results in: C6H8O6
  • β-carotene (the colour in carrots) is made up of 40 C-atoms and 56 hydrogen atoms, resulting in: C40H56

By now you have probably seen a trend in these chemical formulas. They consist of a list of all the atoms types present in a certain molecule. In a subscript the number of each atom is indicated after the respective letter. So in water the 2 refers to the number of hydrogen atoms. If only 1 atom is present of a certain type, no number will be included.

What you can also see is that a very large molecule such as β-carotene can have a pretty simple chemical formula.

Examples of chemical formulas in food

To get more familiar with the concept of chemical formulas, here are some more very common food molecules written as a chemical formula:

  • Glucose – C6H12O6
  • Sucrose (standard sugar) – C12H22O11
  • Lactose – C12H22O11
  • Linoleic acid (a fatty acid) – C18H32O2
  • Baking soda (part of baking powder): NaHCO3
  • Starch (part of flour): (C6H10O5)n (the n indicates it can be a long chain of these groups of molecules)
  • One of the fatty acids in butter (palmitic acid): C16H32O2
  • Salt: NaCl (salt is not really a molecule though since these are two ions, but that’s a more in-depth discussion to have)

 

Disadvantage: chemical formulas do not show structures

What you might have also noticed is that chemical formulas are great for showing which atoms are present in a certain molecule, however, they do not say in any way how those different atoms are connected. For certain applications that is not a problem, however, for properly understanding what happens in a chemical reaction, chemists do have to know how these atoms are connected. For that purpose they have a different system, using drawings of molecules to indicate how the different atoms are connect.

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