Chemistry in Cooking: The Science Behind Your Favourite Foods

Cooking is a mysterious blend of art and science, with love and creativity playing as much of a role as heat distribution and timing. Every time we step into the kitchen, we become creative chemists, conjuring up delicious experiments that (hopefully) tantalise our taste buds.

Of course, experimentation can lead to mixed results, especially if you don’t understand the chemical reactions at play when you fire up the stove or get your slow cooker simmering. If you want to sit down to more delectable dishes and fewer “meh” meals, you’re in the right place.

This article will guide you on a gastronomic journey through the fascinating world of food science, revealing the secrets behind the alchemy that turns food items into culinary masterpieces.

The Chemistry of Cooking

Cooking involves a series of intricate chemical reactions that transform raw ingredients into entirely new flavours and textures. In some cases, foods that are unpalatable morph into delicacies when cooked.

You’re unlikely to bite into a raw onion or garlic cloves. But saute or roast those beauties, and people start salivating. Some foods like quince or rhubarb are inedible when uncooked but grace the menus of some of the finest restaurants.

Behind those seemingly simple everyday processes that occur on your stovetop or oven, lies a whole world of fascinating scientific interactions that many people don’t know enough about. Known to the experts as “molecular gastronomy”, the chemistry of cooking does not have to remain a mystery.

Grasping these secrets can help make you a better chef. Let's delve deeper into some of the most common chemical reactions that occur in the kitchen.

The Maillard Reaction: Beautiful, Crispy, and Brown

Discovered in 1912, the Maillard reaction is the scientific explanation behind the mouthwatering deliciousness of browned and crisped dishes. This complex reaction occurs when amino acids (proteins' building blocks) and reducing sugars (sugars with a specific chemical structure) meet at high temperatures.¹ The Maillard reaction is responsible for:

• Seared Steaks and Crispy Crusts: The beautiful browned surface of a perfectly seared steak and the golden brown crunch of toasted bread or potatoes are both products of the Maillard reaction. This reaction creates a feast for the eyes with cooked meats, roasted vegetables, and perfectly browned toast.
• Rich Flavours: Beyond beautiful colours, the Maillard reaction also unleashes a rich array of flavour compounds, contributing to the complex taste profiles of roasted coffee, caramelised onions, and perfectly browned burgers. By controlling the temperature and cooking time, you can influence the intensity and specific flavours produced by the Maillard reaction.

Be careful, however! Too much Maillard is not a good thing! Overcooking or excessively charring foods at high temperatures can be harmful to your health, so be sure to use your Maillard reaction wisely!

Caramelisation: Science Gets Sweet

Like the Maillard reaction, caramelisation involves heating sugars. The point of differentiation lies in the fact that caramelisation doesn't require the presence of proteins. When sugar molecules are subjected to high heat in a low-moisture environment, they break down and rearrange², giving you a range of deliciously luxurious features:

• Deeper Colours: The sugar transforms from pale to rich amber or deep brown, adding visual appeal to dishes like caramelised onions or crème brûlée. The colour change indicates the level of caramelisation, with darker colours signifying a more intense reaction.
• Intensified Flavours: The breakdown of sugars also creates a range of flavourful compounds, bringing the distinct caramel taste we love to confectionary, sauces, and desserts. The specific flavours produced depend on the type of sugar used and the degree of caramelisation.

Pyrolysis: The Delicate Dance in Your Frying Pan

Love a good fry-up? If so, you’ve probably seen pyrolysis in action. It's a process in which high heat breaks down a substance (like food) in the absence of oxygen. This breakdown can take you down one of three paths:

• The good: Pyrolysis can initiate caramelisation, creating the delicious colour and rich flavours we love.
• Rich Flavours: If you let your food linger in the heat for a little too long, it can start to burn, degrading that beautiful caramelisation you worked so hard to create.
• Rich Flavours: Left on high for too long, pyrolysis can lead to charring. While a touch of char can add smoky depth to some foods, too much can ruin your meal (and set off your smoke alarm).

The key to avoiding burnt offerings is finding the sweet spot between caramelisation and charring. This is where using the right pan can make a big difference. A healthy, non-stick pan with excellent heat distribution can help you to achieve the perfect sear and crisp without burning your food.

Fermentation: Bubbly, Heat-Free Fun

Fermentation is an ancient process with a modern twist. Here, carbohydrate molecules like sugars and starches are broken down by microorganisms such as yeast and bacteria, but without heat.⁴ This process is responsible for some of our favourite fermented delights and has been particularly on-trend in recent times due to their incredible health benefits.

While most people have a negative attitude towards bacteria, many of these microbes are, in fact, incredibly good for us. For this reason, you’ve probably seen plenty of people spruiking fermented foods on news sources and social media.

Healthy bacteria help to create a healthy gut biome, assisting our bodies to synthesise numerous vitamins and amino acids, among other beneficial functions. Popular fermented foods include the following:

• Alcoholic Beverages: Beer and wine are all products of fermentation, in which yeast converts sugars into alcohol and carbon dioxide. Carefully controlling the types of yeast, sugar, and fermentation conditions allows brewers and vintners to achieve their desired flavours and alcoholic content.
• Kombucha: The wildly popular recent addition to many people’s repertoire is as healthy as it is delicious, thanks to the exact same bioprocess as beer and wine.
• Tangy Gut-Friendly Treats: Yoghurt, kimchi, and sauerkraut owe their signature tang to the action of lactic acid bacteria (also known as lactobacillus), which convert sugars into lactic acid. This process also preserves vegetables, extending their shelf life and creating a complex flavour profile.
• Leavened Breads: Sourdough bread rises and gets fluffy thanks to wild yeast and bacteria naturally present in the flour. These bacteria ferment sugars and produce carbon dioxide gas, creating air pockets in the dough. Understanding fermentation allows bakers to control the rise and flavour of their breads.

Acid-Base Reactions: A Question of Balance

Acids and bases are one of the primary determinants of the flavour profiles of your favourite ingredients. The chemical interactions between foods with varying pHs can help you create all sorts of interesting reactions in your kitchen. The key is to know where to find them and how to use them.

Here's a simplified breakdown:

• Acids: If something’s got a sour tang, it’s probably acidic (think lemons, limes, tomatoes, and vinegar). These tangy tongue ticklers can tenderise proteins, making tough cuts of meat more enjoyable. A marinade with acidic ingredients like lemon juice can soften the meat while boosting flavour. Some foods, such as fish, can actually be “cold cooked” with acidic liquids. A well-known example is ceviche, a raw fish dish cooked by marinating it in vinegar.
• Bases: Bases, like baking powder and eggs, counteract acids. In baking, bases react with acids to create gas bubbles that leaven dough, giving your cakes and breads that perfect rise and fluffiness. They also help neutralise the sour taste of acids, creating a balanced flavour profile. If you’ve ever wondered how a splash of maple syrup or agave can magically cut through the sharpness of vinegar in a salad dressing, now you know why!

Liquid Alchemy: Turning Water into Flavour

While heat ignites the chemistry of cooking, there's a whole world of flavour waiting to be unlocked through liquid techniques. Here's a breakdown of three essentials:

• Marinating: This flavourful bath infuses your food with deliciousness while tenderising it with acidic ingredients like vinegar or citrus. Experiment with marinades to find your perfect flavour profile.
• Brining: This salty soak infuses moisture, enhances flavour, and improves texture by drawing water into the muscle or plant fibres, partially dissolving tough proteins. The result? Juicier, more flavourful meat that's melt-in-your-mouth tender.
• Basting: Continuously brushing or spooning melted fat, pan drippings, marinades, or stock onto your food keeps it moist and promotes browning for a beautiful golden finish. With every baste, you create another rich layer of flavour.

Ready to Unleash Your Inner Kitchen Chemist?

When you understand the science behind cooking, you take the guesswork out of the kitchen and empower yourself to create delicious and consistent results. By harnessing the power of chemical reactions like fermentation, the Maillard reaction, and caramelisation, as well as mastering techniques like marinating, brining, and basting, you can elevate your cooking to a whole new level.

For many home cooks, these are all cooking phenomena you have worked with without knowing since you first picked up a pan. Understanding exactly how these complex chemical reactions work will help you control them more precisely and develop your skills beyond your expectations.

You might not think of your kitchen as a chemistry lab. However, when you change how you view the changes that occur when you cook your food, your family and friends will thank you whenever they sit down at the table to tuck into your latest scrumptious creation.

End Notes

1. Maillard Reaction | Science Direct https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/maillard-reaction#:~:text=The%20Maillard%20reaction%20is%20the,polymerise%20to%20form%20brown%20pigments.

2. What Does Caramelized Mean, Anyway? | Bon Apetit https://www.bonappetit.com/story/what-does-caramelized-mean

3. What Is Pyrolysis? | USDA Agricultural Research Service https://www.ars.usda.gov/northeast-area/wyndmoor-pa/eastern-regional-research-center/docs/biomass-pyrolysis-research-1/what-is-pyrolysis/#:~:text=Pyrolysis%20is%20the%20heating%20of,strong%20bio%2Dpolymers%20mentioned%20above.

4. The Role of Yeasts in Fermentation Processes | National Library of Medicine https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7466055/#:~:text=Upon%20a%20strictly%20biochemical%20point,by%20converting%20sugar%20into%20alcohol.