Emulsions

An emulsion is a stable mixture of two liquids that normally refuse to combine — almost always oil and water. Emulsions are everywhere in cooking: milk, cream, butter, mayonnaise, hollandaise, vinaigrettes, and most pan sauces.

How emulsions work

Every emulsion has two phases:

• Continuous phase — the liquid that forms the background. In cream and mayonnaise, this is water. In butter, it’s fat.
• Dispersed phase — tiny droplets (0.1–10 micrometers) suspended within the continuous phase.

Left alone, oil and water separate because oil droplets coalesce — they merge into larger and larger pools until the two liquids are fully separated. Emulsions prevent this through emulsifiers: molecules that are amphipathic (one end loves water, the other loves fat). They arrange themselves at the oil-water interface, coating each droplet in a protective shell that prevents coalescence.

Microwave Cooking

Microwave ovens heat food through a mechanism fundamentally different from every other cooking method: electromagnetic radiation at a specific frequency directly excites polar molecules — primarily water — causing them to rotate. Molecular friction from this rapid rotation generates heat from within the food, bypassing the surface-in heating that defines conventional cooking. The result is extraordinary speed but an inability to brown, crisp, or develop the complex flavors that come from high-temperature surface chemistry.

Water in Cooking

Water is the dominant molecule in nearly all foods — raw meat is ~75% water, fruits and vegetables up to 95%, human bodies ~60%. Its seemingly simple structure (two hydrogens, one oxygen) conceals unusual physical properties that govern almost every aspect of cooking: how food heats, how it freezes, why steam scalds, why salt preserves, and why oil and water won’t mix.

Hydrogen bonding: the master property

Oxygen pulls more strongly on shared electrons than hydrogen does, making water an electrically asymmetrical (polar) molecule — positive at the hydrogen end, negative at the oxygen end. This polarity creates hydrogen bonds: weak electrical attractions between the negative oxygen of one molecule and the positive hydrogen of another. In liquid water, each molecule participates in 1–4 hydrogen bonds at any moment, constantly forming and breaking.

Wet Heat Methods

Boiling, simmering, poaching, and steaming share a defining constraint: water’s boiling point (212°F/100°C at sea level) sets a hard ceiling on food temperature. This is too low for Maillard browning (~280°F) or caramelization (~330°F), which is why wet-heat-cooked foods remain pale and mild compared to their dry-heat counterparts. The tradeoff is gentleness — wet heat preserves delicate textures, retains moisture, and delivers uniform temperature with no hot spots.

Boiling

Water at a full rolling boil (212°F) with vigorous convection currents that circulate heat efficiently throughout the pot. The entire medium reaches uniform temperature quickly. Best for foods that can tolerate agitation: pasta (starch gelatinizes), vegetables (softens cellular structure), eggs (proteins denature and set).