Vol. IX · Fats and Oils Plate 2 of 10melting range, solid fat, butter, lard, coconut oil, cocoa butter, tallow, olive oil, crystals, mouthfeelMT

Melting Ranges.

Butter is hard at 4 °C, spreadable at 20 °C and gone at 35 °C. Cocoa butter holds out until just below body heat, which is why chocolate melts in the mouth and not in the hand.

Pure substances melt at one temperature. Fats are mixtures of hundreds of different triglycerides (V.6), each with its own melting point, so a fat softens gradually as more and more of its molecules let go. What matters to a cook is the solid fat share at the temperature of the work: how much of the fat is still crystals in the fridge, on the counter, in the hand and in the mouth.

Butter is mostly solid in the fridge and about a sixth solid at room temperature — plastic enough to cream with sugar (XXIV) or roll into pastry (XXV). Lard and tallow stay firmer, which gives flaky pie crusts and the crisp of 猪油 pastry. Coconut oil switches sharply from hard to liquid around 24 °C. Cocoa butter is mostly solid until about 30 °C and gone by 35 °C: chocolate's snap and its melt in the mouth. Olive oil is liquid even in the fridge. The workshop draws each melting curve.

Below: the solid share of seven fats against temperature, with the fridge, the kitchen and the mouth marked, and the share at the temperature you choose (teaching curves shaped on published solid-fat figures).

What you will learn
Workshop
Solid share of each fat against temperature: logistic teaching curves placed on published solid-fat-content figures (butter mostly solid at 4 °C and about a sixth at 20 °C; cocoa butter mostly solid at 20 °C and melted by 35 °C; coconut oil melting sharply near 24 °C).

The right fat for the temperature

Butter from the fridge is about 73 % solid in this model, which is why it tears bread; at 20 °C it is about 16 %, soft enough to cream. Cocoa butter is 99 % solid at 20 °C and 10 % at 35 °C: firm in the hand, liquid on the tongue. Coconut oil is 82 % solid at 18 °C and 8 % at 26 °C, so the same jar is a white block in a cool kitchen and a clear oil in a warm one.

Choose by the job. For flaky pastry, a fat that stays plastic and in pieces through rolling — cold butter, lard (XXV.5). For creaming, butter at about 18–20 °C, soft but not melting. For a frying oil that flows at room temperature, a liquid oil. For chocolate that snaps and melts in the mouth, cocoa butter in its proper crystal form (XXV.10). And for a dressing kept in the fridge, an oil that stays liquid there — olive oil clouds and thickens when cold, which does not harm it.

At the stove

Put a pat of butter, a spoon of coconut oil and a square of chocolate on three saucers in the kitchen, then hold each in your palm for a minute. Notice which softens in the hand and which waits for the mouth.

Chinese pastry cooks prize lard (猪油) for 酥皮 because its crystals are coarse and stay plastic over a wide range, giving crisp, flaky layers; many modern bakers use it mixed with butter for flavour and handling.

Terms

Melting range
The span of temperature over which a fat goes from solid to liquid.
Solid fat content
The share of a fat that is crystalline at a given temperature.
Triglyceride
A fat molecule: glycerol with three fatty acids (V.6).
Plastic fat
A fat soft enough to shape but firm enough to hold, as butter at 18–20 °C.
Fats melt over a range; the solid share at the working temperature decides how they behave.

Sources

  1. A teaching value chosen for the course: the right order of magnitude and shape, not a measurement of a particular food.
  2. H. McGee, On Food and Cooking: The Science and Lore of the Kitchen, 2nd ed., Scribner, 2004.