Food Chemistry Project – 3 – Identifying the Big 3
So, let’s try to apply what we’ve learned again! Remember how in the previous exercise you looked up at least 5 molecules present in your chosen food? We’re going to have a closer look at those and look at the big 3 in your chosen food. Do the following:
- Identify whether any of those five identified molecules in the previous exercise were carbohydrates, proteins or fats. If yes, identify to which group they belong.
- Note, they don’t necessarily have to belong to any of the three groups.
- Use one of the previously used databases (e.g. FoodDB of the USDA nutrient database, or your national nutrient database) and look up how much carbohydrates, proteins and fats your chosen food contain. Does it align with what you had expected? Any surprises?
Keep these notes, we’ll be discussing where the Big 3 shows up in your food and how it influences its behavior next!
Our apple
So let’s have a look at our apple which we’ve chosen as an example project. We identified both sucrose and fructose in our apple. These are both small carbohydrates. This makes a lot of sense for an apple. Apples are juicy (lots of water) and sweet (sugar = carbohydrates)!
We then looked up our apple (we went for Honeycrisp here) on the USDA nutrient database and found the following:
Apples barely contain any fats, nor proteins. They are made up of mostly water and sugars. This is exactly what we would have expected. Apples, like most fruits, are watery, sweet products.
Source: USDA, Food Data Central, Apples, honeycrisp, with skin, raw, FDC ID: 1750343, link
Share your results or ask a question!
What did you find in your food?
I found that 100 g lemon flesh and juice contained negligible protein and fat. It comprised mostly moisture and dietary fibre, with 1.8 g carbohydrates (fructose, glucose, sucrose):
Proximates
Energy, without dietary fibre 95 kJ
Energy, including dietary fibre 115 kJ
Moisture 89 g
Protein 0.6 g
Nitrogen 0.1 g
Fat 0.2 g
Ash 0.2 g
Dietary fibre 2.5 g
Fructose 0.6 g
Glucose 0.8 g
Sucrose 0.4 g
Maltose 0 g
Lactose 0 g
Total sugars 1.8 g
Starch 0 g
Available carbohydrate, without sugar alcohols 1.8 g
Source: Food Standards Australia New Zealand Database
Isn’t it interesting how lemons barely contain any of the big 3, nevertheless are such a crucial part of our diet and cooking? In the case of lemons, it’s not necessarily about the big 3. Instead, its main role revolves around its acidity. With that acidity it can accelerate or initiate chemical reactions and changes in the big 3, so indirectly impacting those. For instance, adding lemon juice to a boiling sugar syrup will break down the sugar into smaller parts. So it’s definitely more of a supporting act than the main play.
Also, the acidity plays a crucial role for overall flavor perception in our mouth.