How do you properly emulsify a vinaigrette?

A stable vinaigrette is an oil-in-water emulsion in which small droplets of oil are suspended in an aqueous phase of vinegar or lemon juice. Harold McGee, food science writer and author of On Food and Cooking, explains that emulsifiers are amphiphilic molecules that sit at the oil–water interface and lower interfacial tension, preventing droplets from coalescing. Practically, that means choosing an emulsifying agent and applying mechanical force while controlling proportions and temperature.

Basic chemistry of emulsification

Start with a plausible ratio as a baseline and adjust for taste; many cooks begin with three parts oil to one part acid for a balanced flavor. Add an emulsifier such as Dijon mustard or egg yolk, which contribute proteins and lecithin that McGee describes as particularly effective at stabilizing emulsions. Whisking or blending introduces shear that breaks oil into fine droplets, increasing the surface area that the emulsifier must cover. America's Test Kitchen reports that a steady, gradual addition of oil while whisking produces smaller droplets and a creamier, longer-lasting emulsion than dumping oil in all at once. Temperature matters too: room-temperature ingredients blend more readily than cold ones because viscosity is lower and droplets form more easily.

Technique and safety considerations

Begin by combining acid, salt, and any soluble flavorings so that sugar or salt can dissolve. Add the emulsifier and start whisking vigorously, slowly streaming in the oil. A jar shaken vigorously or an immersion blender set to pulse will produce similar results with less effort. For greater stability, use an egg yolk or a small amount of commercial emulsifier. If using raw egg yolk, follow food-safety guidance from the United States Department of Agriculture and the Centers for Disease Control and Prevention regarding storage and populations at risk from Salmonella, and consider pasteurized yolks as an alternative.

Relevance, causes, and consequences

Understanding emulsification is more than culinary technique; it explains why some dressings break and how to prevent that. Insufficient emulsifier, overly rapid oil addition, or large oil droplets cause phase separation. Consequences range from an unappealing split dressing to waste of ingredients. Knowing the science allows cooks to tailor texture and shelf life: stronger emulsions cling better to greens in a restaurant service context, while lighter, loosely emulsified dressings may be desired for delicate salads.

Cultural and environmental nuances

Vinaigrette has roots in French cuisine and has become a global template adapted to local oils, acids, and flavors. The choice of oil influences taste, health profile, and environmental footprint; extra-virgin olive oil imparts fruitiness while seed oils offer neutrality. Regional practices reflect ingredient availability and culinary preferences, from citrus-based dressings in Mediterranean and Latin American cuisines to mustard-forward dressings in Northern Europe. Mastering emulsification therefore connects technique, sensory outcome, and broader food-system considerations, enabling cooks to create stable, flavorful vinaigrettes that suit both palate and context.