Cooking Methods and Heat Transfer
Cooking Methods and Heat Transfer tests whether you can explain how heat reaches food, predict what it does to protein, starch, sugar and pectin, and then choose a method that suits the product. Expect definitions of moist, dry and combination methods with their temperature ranges, plus the science behind browning and tenderising.
Heat transfer
- Conduction: direct contact, as with a pan, grill bars or hot oil.
- Convection: moving air or liquid, as in an oven, a stock pot or a fryer; forced convection is faster, so lower the setting 10–20 °C.
- Radiation: infrared and grill elements; microwaves excite water molecules directly.
- Induction: electromagnetic, so the pan itself becomes the heat source and must have a magnetic base.
Moist methods (70–100 °C)
- Poach 70–85 °C, simmer 85–96 °C, boil 100 °C, steam 100 °C.
- Suited to delicate proteins, vegetables and starches where gentle heat preserves texture.
Dry methods (surface above 140 °C)
- Roast, bake, grill, griddle, sauté, pan-fry, deep-fry at 160–180 °C, en papillote.
- Maillard browning needs a dry surface and about 140 °C; sugar caramelises from about 160 °C.
Combination methods
- Braise, stew, pot roast and fricassee: sear, then cook moist, low and covered.
- Collagen converts to gelatin at 70–80 °C over hours, which is why tough cuts become tender.
What heat does to food
- Proteins denature and shrink at 60–70 °C, expelling water.
- Starch gelatinises at 62–80 °C and thickens liquid.
- Pectin softens at 80–90 °C; acid slows softening and alkali speeds it.
- Vitamin C and chlorophyll degrade with heat, water and air.
Worked example
Beef shin is high in collagen and fillet is low. Shin at 55 °C is tough, but braising at 90 °C for three hours converts collagen to gelatin and gives fork-tender meat. Fillet treated the same way becomes dry and stringy; it needs dry heat to 55–58 °C plus a rest. The method follows the connective tissue, not the price of the cut.
Traps that cost marks
- Repeating that searing seals in juices; it does not.
- Frying below 160 °C, which produces greasy food.
- Overcrowding a pan so the food steams instead of searing.
- Boiling a stock or a braise that should simmer.