What do the golden crust on a loaf of bread, the perfectly aerated crumb of a cake, and the browning of a steak in a frying pan all have in common? Science.
Cooking is all about chemistry. You may not realise it, but experiments and chemical reactions are happening in your kitchen on a daily basis.
It can be fascinating to learn more about the science of cooking, from heat reactions to fermentation.
Understanding these processes can even help you become a better cook, improving both your techniques and the flavour of the food you prepare.
You can learn how to boost the flavour of fruits with citric acid, make fluffier pancakes with baking soda, and even make your own kimchi by fermenting cabbage.
In this post:
Key Takeaways
Cooking is chemistry – transforming food on a molecular level
Proteins, fats, and carbohydrates all react differently to heat
Visible reactions such as caramelisation and fermentations are examples of science at work
Simple kitchen experiments can be both fun and educational
Understanding the Science Behind Everyday Cooking
At its core, cooking is all about molecules and how they interact with each other. It’s how heat transfer and chemical reactions can change the structure of ingredients at a molecular level.
Techniques such as searing, emulsification and caramelisation all have different effects, creating new flavours, colours and textures. Using water to boil, steam or bake can change the way molecules bond, softening foods or helping them rise. Even the type of water matters – with deionised water behaving differently from ordinary tap water.
Mixing oil and water creates emulsions, while mixing starch and water acts as a thickening agent. Lemon juice and other acids can tenderise meat by breaking down its proteins, while bases such as baking soda can raise pH levels – this affects colour and browning.
There are so many different ways to apply heat to food, including convection, conduction, and radiation. You can boil or fry meat at very hot temperatures, melting fats and facilitating lipid oxidisation, or poach or stew it at low temperatures to break down collagen into soft gelatin, encouraging the release of flavours and the reabsorption of moisture.
Ultimately, the simple act of cooking dinner for your family is packed full of fascinating scientific processes.
How Heat Changes the Structure of Food
The application of heat is one of the main ways you can transform the molecules in ingredients.
When you apply heat:
- Proteins denture and coagulate – for example, eggs turning from runny to solid
- Starches gelatinise as they absorb water – softening potatoes, pasta, and rice
- Water evaporates – which concentrates flavours in sauces and roasted vegetables
- Sugars melt and caramelise – this adds colour and sweetness, as well as a delicious aroma
However, temperature control is very important. If the heat is too high or uneven, sugars can burn and proteins can toughen up.
The Role of Proteins, Fats, and Carbohydrates
To get to grips with the chemistry of cooking, you need to understand the different types of molecules found in food and drink.
These are:
- Proteins – which provide structure and texture, and react with heat and sugar. This is what happens when browning meat, for example.
- Fats – these carry flavour, lubricate, and create emulsions. For example, when making mayonnaise or making buttercream.
- Carbohydrates – these thicken sauces, break down into sugars, and caramelise. For example, when using flour to create a roux-based sauce, or caramelising onions.
Combining fats and proteins in different ways can change texture and taste significantly. For example, a cake made with butter will be denser, with a richer flavour. One made with vegetable oil will be moister and softer, because oil reduces gluten formation.
Fascinating Food Reactions You Can See in Your Kitchen
Once you start thinking of cooking as chemistry, you’ll find lots of opportunities to see fascinating food reactions happening right before your eyes.
Many of these are sensory, where you can see, smell, and taste the changes taking place. Looking at these reactions more closely can deepen your understanding of the science of cooking, and encourage you to experiment further.
Caramelisation, Maillard Reaction, and Browning
One of the most visibly obvious chemical reactions you’ll see in the kitchen is caramelisation.
This is a process triggered by heat, which involves the breakdown and rearrangement of sugar molecules into new chemical compounds such as glucose and fructose. The result? A rich, brown colour and deliciously sweet, nutty flavour.
Another common chemical reaction in cooking is called the Maillard reaction. This is where proteins and sugars react under heat. A chemical reaction takes place between amino acids and reducing sugars, creating a browning effect and deliciously complex flavours.
This process happens when you sear a steak, roast coffee beans, or even toast a slice of bread.
Both of these processes result in browning, which adds a great deal of flavour and gives food a rich, appetising smell.
Fermentation and the Magic of Microorganisms
Fermentation can be absolutely fascinating, and it’s easier than you think to try at home.
It involves microorganisms such as yeast, bacteria, and moulds, which turn sugars into acids, gases, or alcohol. Salt can play a role in this process too, such as drawing moisture out to inhibit microbial growth.
Here are just a few examples of these magical microorganisms in action:
- Yeast makes bread rise by producing carbon dioxide
- Bacteria turns milk into yoghurt, or cabbage into kimchi
- Yeast and bacteria together can ferment beverages such as beer, wine, and kombucha
Tips for Experimenting with Kitchen Chemistry Safely
While experimenting in the kitchen is fun and can teach you a huge amount about the chemistry of cooking, it’s important to stay safe.
Here are some tips to bear in mind:
- Use oven mitts and safety glasses/goggles for hot or boiling experiments
- Ventilate your kitchen when caramelising or roasting to avoid smoke buildup
- Start with small batches to reduce risk
- Avoid dangerous chemical experiments, like mixing acids with baking soda indoors
- Keep children and pets away from the kitchen when carrying out any experiments
Conclusion
Cooking is an everyday necessity, an art and a science all in one. Each meal you make transforms ingredients at a molecular level, whether you’re whipping up a sauce, making a Sunday roast, or being adventurous with a soufflé. So the next time you cook, remember: you’re not just making dinner – you’re conducting a delicious science experiment.
