Vol. X · Emulsions, Foams and Gels Plate 5 of 11hollandaise, béarnaise, beurre blanc, egg yolk, butter, warm emulsion, curdling, temperature, bain-marieHT

Hollandaise and Beurre Blanc.

A warm butter sauce lives in a window about thirty degrees wide. Too cool and the butter sets; too hot and the yolk scrambles.

Hollandaise and béarnaise are warm cousins of mayonnaise: melted butter whisked into egg yolk with a little water and acid. The butter's fat forms the droplets (X.4), and warm yolk proteins, beginning to thicken from about 60 °C (VI.3), give the sauce body. Beurre blanc uses no yolk at all: cold butter whisked into a hot reduction of wine and shallots, held by the butter's own milk proteins and the reduction's solids.

Both have a temperature window. Below about 35 °C butterfat begins to crystallise (IX.2): the sauce stiffens and looks greasy. Above about 82–85 °C the yolk proteins coagulate into tiny curds and squeeze out the butter: the sauce splits and grains. Between, it is glossy and thick. That is why these sauces are made over barely simmering water, held in a warm (not hot) place, and why a split sauce is rescued with a spoon of cold water or a fresh yolk. The workshop warms the sauce.

Below: how thick, how set and how curdled a yolk-and-butter sauce is against its temperature (colloid bench, using the course rates for yolk proteins and teaching ranges for butterfat), and the state at your temperature.

What you will learn
Workshop
Colloid bench: yolk thickening is the course yolk-protein transition held three minutes at the temperature; butterfat setting begins below 35 °C (teaching range); curdling from about 82 °C and complete by 88 °C (teaching range, consistent with the yolk's setting above 70 °C when held).

Keep it in the window

In this model the sauce is good from about 42 °C to about 85 °C: below that range the butter starts to set, and above it the yolk curdles. A cook aims for the middle, around 60–70 °C — warm to the finger, not hot — and keeps it there by working over a pan of water that is steaming, not boiling, or in a heavy bowl off the heat, whisking constantly so no part of the yolk touches hot metal too long.

Holding and rescuing. Keep the finished sauce in a warm vacuum flask or over water no hotter than 65 °C, never on a direct flame; whisk in a spoon of warm water if it thickens. If it starts to look grainy at the edges, whisk in a tablespoon of cold water at once to drop the temperature. If it has split, whisk it a little at a time into a fresh yolk with a spoon of warm water over gentle heat, as with mayonnaise. Beurre blanc must be kept warm but never boiled, or its butter separates into fat and whey.

At the stove

Make a small hollandaise with one yolk and 100 g of melted butter over a pan of barely simmering water, with a thermometer in the bowl. Note the temperature at which it turns thick and glossy, and keep it under 75 °C.

Despite its name, sauce hollandaise appears in French cookery from the seventeenth century; the name may honour Dutch butter. Béarnaise, flavoured with tarragon and shallot, was first served in the 1830s near Paris, not in Béarn.

Terms

Hollandaise
A warm emulsion of butter in egg yolk with water and acid.
Béarnaise
Hollandaise flavoured with a reduction of vinegar, shallot and tarragon.
Beurre blanc
Cold butter whisked into a hot wine and shallot reduction, with no yolk.
Splitting
A sauce separating as proteins curdle or fat escapes.
Warm butter sauces live between about 50 and 80 °C: below, the butter sets; above, the yolk curdles. Rescue with cold water or a fresh yolk.

Sources

  1. Egg proteins: ovotransferrin sets near 62 °C, ovalbumin near 80 °C, the yolk thickens near 65 °C and sets near 70 °C (H. McGee, On Food and Cooking, 2004, ch. 2; P. Barham, The Science of Cooking, 2001).
  2. A teaching value chosen for the course: the right order of magnitude and shape, not a measurement of a particular food.
  3. H. McGee, On Food and Cooking: The Science and Lore of the Kitchen, 2nd ed., Scribner, 2004.