What Is Cooking? The Science Behind Food Transformation - Section 3: Fundamental Food Transformations

When we cook food, several key transformations occur that change both its nutritional value and sensory qualities.

Protein denaturation is perhaps the most visible transformation in many foods. Proteins are complex molecules folded into specific three-dimensional shapes. Cooking "denatures" these proteins, causing them to unfold and reform into different structures. We see this when egg whites turn from clear to white when cooked, when meat becomes firmer and changes color, or when fish becomes flaky instead of glossy and translucent. While we most commonly use heat to cause denaturation, acids (like lemon juice or vinegar), salt, and even physical agitation (like whipping egg whites) can also trigger this transformation.

The breaking down of cell structures represents another fundamental change. Plants have rigid cell walls made of cellulose that our bodies cannot easily digest. Cooking breaks down these cell walls, making nutrients more accessible, softening texture, and releasing flavors trapped within cells. This explains why cooked vegetables are generally softer than raw ones, and often allow us to absorb more nutrients despite some vitamin loss during cooking.

Starch gelatinization provides thickness and substance to many cooked foods. Starches are complex carbohydrates found in foods like potatoes, rice, and flour. When heated with water, starch molecules absorb water and swell, creating a thicker, more digestible texture. This process explains why rice grains plump up when cooked, why flour thickens sauces when heated, and contributes to how bread dough becomes elastic when kneaded and baked.