THE SCIENCE OF HEAT AND COLD Flashcards
How did discovering fire help our ancestors?
Protection from predators and cooking food. We no longer spent the day grinding through plant matter. Now humanoid ancestors could use extra time to explore, build and hunt - be human.
How did cooking help higher brain function?
Cooking made it easier to digest high-quality proteins, especially meat; therefore the link between the advent of fire and human brain development.
What is heat?
A form of energy. Term describes the speed of molecules in a substance such as air or water. The higher the temperature the faster the molecules are moving and the more energy, or heat, the molecules contain.
How is heat transferred molecularly?
Fast-moving molecules bump into slower-moving ones, causing them to pick up speed.
What wide range of changes can occur when molecules in food speed up?
Food can change color, lose moisture and their integrity (more tender).
Most common forms of heat in cooking
Conduction, convection and radiation.
Does heat always makes food taste better?
No, it can spoil the taste of food; oils oxidize and bitter substances are released.
Sauté
Cook foods in a thin film of hot fat in a skillet or hot burner.
Sautéing work best for what foods?
Flat, relatively thin foods, such as steaks, chops, and cutlets, as well as small items, such as chopped vegetables, shrimp or scallops.
Roast
Cook foods in a pan in a hot oven.
Roasting works best with what foods?
A wide range of foods from large cuts of meat and whole birds to sliced potatoes.
Fry
To cook in a significant quantity of hot oil in a skillet or pot set on a hot burner.
Frying works best for what foods?
Many of the foods that are best for sautéing can also be fried; many fried foods are breaded or battered.
Shallow-frying or pan-frying
Food can be partially submerged in oil. Generally employs a skillet and a modest amount of oil (about 1 cup).
Deep-frying
Food can be completely submerged in oil. Requires use of a large pot and 1 to 2 quarts of oil.
Boil
Cook foods in boiling liquid in a pot set on a hot burner.
Boiling works best with what foods?
Best with pasta, grains and vegetables.
Is the temperature of boiling water constant?
No, water boils at 212ºF around sea level. The boiling drops 2 degrees for every 500-foot increase in elevation. No matter the temperature, when a liquid boils, large bubbles energetically break the surface of the liquid at a rapid and constant pace.
Why does the boiling point of water change depending on atmospheric pressure?
Additional pressure translates as increased resistance in the air to the release of liquid molecules turned into gas, thus requiring more energy to complete the reaction.
Simmer
To cook foods in liquid that is just below the boiling point in a pot set on a hot burner.
What is another term for simmer?
Gentle boil
What is the temperature range for simmering?
180 to 205 degrees. When a liquid simmers, small bubbles break the surfaces at a variable and infrequent rate.
What foods are best for simmering?
Many grains, including rice, are best simmered; it’s usually reserved for tougher cuts or foods that need longer to cook. Simmering is invaluable for stocks, soups and sauces.
Poach
To cook foods in a liquid that is well below the boiling point in a covered pot set on a stovetop. Related to simmering; the temp of the liquid is lower (no bubbles are breaking the surface) and the pot is generally covered to create a constant, gentle cooking environment.
Temperature of poaching water.
160 to 180 degrees.
What foods are best for poaching?
Usually delicate foods like eggs, fish, fruit and some organ meats.
Steam
An especially delicate method cooking foods that are suspended, generally in a basket, over simmering liquid in a covered pot set on a burner.
Best foods for steaming?
Steaming is an excellent choice for vegetables, fish and delicate foods like dumplings.
Correlation between steam and flavor.
Unlike other moist-heat cooking methods, steaming does not wash away flavor.
Braise
To cook food by first sautéing them and then adding liquid, covering the pan, and simmering.
Best foods for braising?
Ideal for tough cuts that require prolonged cooking to become tender, such as pot roast.
Stew
This is a subset of braising; food is sautéd, then simmered
Foods best for stewing.
Generally reserved for recipes that involve small chunks of food, not entire roasts.
Grill
To cook foods an a grate set over fire.
Best foods for grilling.
Although the term “grilling” is often used to describe the preparation of any food cooked over fire, we generally reserve it for foods that cook quickly, such as steaks, cutlets, chops, vegetables and seafood.
Grill-Roast
To cook foods on a grate set over a modest fire confined to a portion of the grill in a closed environment.
Foods best for grill-roasting.
Best for thick, large cuts that require substantial cooking over moderate heat, such as a whole chicken or roast.
How is grill-roasting similar to roasting?
When a lid is placed on a grill, the cooking method resembles roasting, especially if the food is not positioned directly over the fire and thus won’t brown too quickly.
Barbecue
To cook foods on a grate set over a small, smoky fire confined to a portion of the grill in a closed environment.
Foods best for barbecuing.
Best for tough cuts that require prolonged cooking to become tender.
Difference between grill-roasting and barbecuing.
When barbecuing, the setup is the same as with grill-roasting but the fire is smaller and wood is used to create a smoky flavor in the food.
Temperatures below 40ºF can inhibit what in peaches?
Certain enzymes that normally break down pectin in its cell walls during the ripening process.
What do temperatures below 40 degrees do to bacteria?
Suppresses their activity.
What is the “danger zone” for bacterial growth?
40 to 140 degrees.
Moisture of food begins to freeze at what temp?
32 degrees, and whether the moisture is in fruit, ice cream, or meat, it will form crystals.
What happens to frozen fruits and vegetables when thawed?
Ice crystals that formed will rupture cells walls and internal cell organelles in fresh foods, like fruits and vegetables, which release enzymes from their locked compartments. When thawed, these enzymes cause produce to develop off-flavors and turn brown and soggy.
In frozen vegetables, how can enzymes that produce off-flavors be halted?
Blanching. This is how manufacturers keep vegetables from turning to mush or tasting sulfuric when frozen and thawed.
How do manufacturers reduce crystals size of frozen fruits?
Since fruit cannot withstand precooking manufacturers generally add sugar to reduce crystal size and thus limit the damage.
What acid do manufacturers use to deactivates the enzymes that causes browning?
Ascorbic acid.
What is the biggest issue with freezing meat and other protein?
Moisture loss
How do proteins lose moisture due to freezing?
The ice crystals damage the cell structure and, as a result, frozen meat loses more moisture when cooked than meat that was never frozen. In addition, freezing causes moisture loss due to surface dehydration.
TEST KITCHEN: fresh and frozen ground beef, 7oz each. How much moisture was lost?
When cooked, the fresh lost 3/4 teaspoon of water compared to 2 teaspoons in the frozen.
What is freezer burn?
Ice crystals that encrust the surface of food. Caused by the ravages of constant freezing, thawing, and refreezing.
Does your freezer stay a constant temp?
No, constant opening and closing causes foods to continually heat up and cool down which accelerates the damage of ice crystals.
Why are ice cubes rock hard and ice cream soft and scoopable?
Sugar (or and substance that dissolves in water) affects the freezing point of water. The more sugar added, the lower the freezing point.
