Description
An unstable emulsion of cold butter whisked into a reduced acidic liquid, creating a rich, velvety sauce.
Technical
The emulsion forms when butter's milk proteins (casein and whey) interact with the reduced acidic liquid (wine/vinegar reduction). The acid helps stabilize the emulsion by partially denaturing proteins. Lecithin and other phospholipids in butter act as natural emulsifiers.
Culinary Significance
Provides a luxurious texture and bright acidity to balance rich dishes. Must be served immediately as it separates upon standing. The technique demonstrates precise temperature control and emulsification skills.
Science
Primary Reaction
Protein denaturation and emulsification of milk fats
Parameters
Temperature
58°C optimal
50°C to 65°C range
Critical range - too cold won't melt butter properly, too hot breaks emulsion
Time
8-10 minutes
5 minutes – 15 minutes
Includes reduction time and butter incorporation
Equipment