The chemistry of cookies - Stephanie Warren

Summary

This script takes viewers on a scientific journey through the baking of cookies, highlighting the chemical reactions that transform dough into a delicious treat. From the melting of butter at 92°F to the Maillard reactions at 310°F, each stage is a testament to the mad science of baking. The script explains how butter's water turns to steam, proteins from eggs coagulate, and sugars caramelize, all contributing to the cookie's texture and flavor. It ends with a sensory tip: when the nutty, toasty aromas fill the air, your cookies are ready to enjoy with a glass of milk.

Takeaways

• 🍪 The transformation of dough into cookies is a series of chemical reactions triggered by heat.
• 🧈 At 92°F, butter in the dough melts, causing the dough to spread and its water content to turn into steam.
• 🥚 Pasteurization occurs around 136°F, killing bacteria like salmonella in the eggs.
• 🔗 At 144°F, proteins in the eggs begin to denature, helping to solidify the dough's structure.
• 💧 Water boils at 212°F, causing the cookie to dry out and form a crispy texture.
• 🌬️ Baking soda acts as a leavening agent, creating carbon dioxide gas and making the cookie light and flaky.
• 🏿 The Maillard reaction at 310°F gives cookies their brown color and contributes to their flavor and aroma.
• 🍬 Caramelization starts at 356°F, adding the sweet, nutty, and slightly bitter flavors characteristic of caramel.
• 🕒 The oven temperature affects the extent of caramelization and Maillard reactions, influencing the cookie's final color and taste.
• 👃 Your sense of smell can be a reliable indicator of when cookies are done, detecting the aromas of the Maillard and caramelization reactions.

Q & A

What happens to the dough when it reaches 92 degrees Fahrenheit?

The butter inside the dough melts, causing the dough to start spreading out.

Why does the dough spread out when the butter melts?

As the butter melts, its trapped water is released, and as the cookie gets hotter, the water expands into steam, pushing against the dough from the inside.

At what temperature do salmonella bacteria typically die off in the dough?

Salmonella bacteria die off when the dough reaches 136 degrees Fahrenheit.

What changes occur in the proteins of the eggs at 144 degrees Fahrenheit?

At 144 degrees Fahrenheit, the proteins in the eggs start to unfold and get tangled up with their neighbors, forming a linked structure that gives substance to the dough.

How does the water content in the cookie affect its texture as it bakes?

As water boils away at 212 degrees Fahrenheit, the cookie dries out and stiffens, with steam leaving behind airy pockets that make the cookie light and flaky.

What role does sodium bicarbonate play in the baking process of cookies?

Sodium bicarbonate, or baking soda, reacts with acids in the dough to create carbon dioxide gas, which forms airy pockets in the cookie.

What is the Maillard reaction and at what temperature does it occur?

The Maillard reaction is a chemical reaction between amino acids and reducing sugars that gives browned food its distinctive flavor. It occurs at around 310 degrees Fahrenheit.

How do Maillard reactions affect the color and flavor of cookies?

Maillard reactions produce a range of flavor and aroma compounds, which also react with each other, forming more complex tastes and smells, and give foods a rich brown color.

What is caramelization and at what temperature does it start in cookies?

Caramelization is the process where sugar molecules break down under high heat, forming sweet, nutty, and slightly bitter flavor compounds. It starts at 356 degrees Fahrenheit in cookies.

Why might someone set their oven to 310 degrees if they want barely browned cookies?

Setting the oven to 310 degrees Fahrenheit will prevent caramelization, which starts at 356 degrees, resulting in cookies that are barely browned.

How can one determine when cookies are ready without a timer?

One can rely on the smell of the nutty, toasty aromas produced by the Maillard reaction and caramelization as an indication that the cookies are ready.