Why Does Food Stick to the Pan? What Causes the Sizzling Sound When Cooking?

Series: Food Science

Why Does Food Stick to the Pan?

If you’ve ever scrubbed a cooking pan, you might have noticed how foods rich in protein (like eggs, cheese, or meat) tend to stick to the metal surface. This sticking happens due to chemical bonding between the food and the material of the pan—usually metal. These bonds can be weak van der Waals forces or even covalent bonds. Foods high in protein are more likely to stick because proteins can form various complexes with metal atoms (like iron) in the pan.

🧪 What Causes Food to Stick to the Pan?

1. Chemical bonds between the food and the pan’s metal surface.
2. Proteins in food interacting strongly with metal atoms.
3. Insufficient oil, moisture, or improper heating conditions.

✅ How to Prevent Food from Sticking?

1. Using a Non-Stick Coating: TEFLON

The most common non-stick solution is TEFLON (polytetrafluoroethene). TEFLON is a saturated molecule (with only single carbon bonds) and contains very strong C–C (347 kJ/mol) and C–F (485 kJ/mol) bonds. These strong bonds must be broken before any covalent bonds with food can form.

But how does TEFLON stick to the pan itself? This question is better explained by physics than chemistry. Under a microscope, even the smoothest metal surfaces have tiny pores and grooves. When liquid TEFLON is applied, it flows into these imperfections. Once solidified, it locks into the surface mechanically—like in the diagram below:

2. Moving the Food Early On

Another simple way to prevent sticking: move the food around a bit right after placing it in the pan. This avoids prolonged contact with the hot surface, preventing chemical bonds from forming. The surface proteins in the food then begin reacting with other molecules rather than with the pan.

Additionally, oil creates a barrier between the pan and the food. When heated, it allows moisture from the food to evaporate, forming a thin steam layer that keeps the food lifted and prevents sticking. ⚠️ If you don’t heat the oil enough first, the food won’t release enough steam to create this “steam effect,” and it will stick.

3. Preheating Oil Before Cooking

When oil is heated, it becomes less viscous and fills the microscopic grooves in the pan. Near its smoke point (different oils have different points), oil starts reacting with metal atoms on the pan surface, forming a layer called patina. This thin film acts as a protective layer that prevents the food from bonding directly with the metal.

🧽 Note: This patina layer washes away when you clean the pan, so you need to repeat the heating process with oil every time you cook.

🔬 How the Patina Forms (Chemistry Alert 🚨)? - Via cracking and polymerization reactions:

• Cooking oils and fats are esters of glycerol and long-chain fatty acids (e.g., stearic acid: C₁₇H₃₅COOH).
• At high temperatures, the hydrocarbon chains in these fatty acids break down (like in crude oil refining), forming shorter chains, including alkenes (with C=C double bonds).
• These alkenes then polymerize under high heat to form long-chain polymers.
• The result: a high-molecular-weight solid-like film that coats the pan and improves its non-stick properties.

🔊 What Causes the Sizzling Sound When Cooking?

That sizzling sound is actually the steam escaping from the food’s surface when it touches hot oil.

As water evaporates, it produces the familiar “sizzle.” When the sizzling stops, the pan temperature starts to rise quickly, and it’s a sign to be careful—you’re getting close to burning territory!

At around 285°F (140°C), food starts turning golden brown due to the Maillard reaction—a complex chemical reaction between amino acids and reducing sugars that creates flavor and color.

A byproduct of this reaction is water, so you still hear the sizzling as browning begins. But once the food is completely browned and all moisture has evaporated, the sizzling sound fades.