THE PRINCIPLES OF MICROWAVE COOKING
Microwaves are a form of high frequency radio waves similar to those used by a radio including AM, FM and
CB. Electricity is converted into microwave energy by the magnetron tube. From the magnetron tube,
microwave energy is transmitted to the oven where it is reflected, transmitted and absorbed by the food.
Reflection:
Microwaves are reflected by metal just as a ball is bounced off of a wall. For this reason, metal utensils
are not suitable for use in the microwave. A combination of stationary interior walls and a rotating metal turntable or
stirrer fan helps assure that the microwaves are well distributed within the oven cavity to produce even cooking.
Transmission:
Microwaves pass through some materials such as paper, glass and plastic much like sunlight shining
through a window. Because these substances do not absorb or reflect the microwave energy, they are ideal materials
for microwave oven cooking containers.
Absorption:
During cooking, microwaves will be absorbed by food. They penetrate to a depth of about 3/4 to 1 1/2
inches. Microwave energy activates the molecules in the food (especially water, fat and sugar), and heat is produced.
If you vigorously rub your hands together, you will feel heat produced by friction. The internal cooking of larger foods
is done by conduction as the heat which is produced by friction is conducted to the middle of the food. Foods also
continue to cook by conduction during standing time.
FOOD CHARACTERISTICS
Quantity:
The amount of food placed in a microwave oven has a direct effect on the cooking time. Small amounts
of food or liquid require less cooking time than larger amounts of the same substance. As quantity increases,
concentration decreases.
Size:
Small pieces cook faster than large ones. To speed cooking, cut pieces smaller than two inches (5 cm), so
microwaves can penetrate to the middle from all sides. Pieces which are similar in size and shape cook more evenly.
Shape:
Many foods are uneven, like a chicken, ribs or broccoli. The thin parts will cook faster than the thick parts,
while uniformly thick foods cook evenly. To compensate for irregular shapes, place thin pieces toward the center of
the dish and thicker pieces toward the edge of the dish.
Starting Temperature:
Frozen or refrigerated foods take longer to cook than foods at room temperature.
Bone and Fat
: Because bones conduct heat, the side of the meat the bone is on will cook first, while boneless cuts
cook slower but more evenly. Fat attracts microwaves. The middle of these foods is cooked by heat conduction.
Moisture Content:
Microwaves are attracted by moisture. Naturally moist foods absorb microwaves better than dry
ones. Add a minimum of liquid to moist foods, as excess water slows cooking.
Density:
The density of food determines how easily the microwaves can penetrate and how quickly it will cook.
Porous foods, like chopped beef or mashed potatoes, microwave faster than dense ones like steak or whole potatoes.
Piercing:
Steam builds up pressure in foods which are tightly covered by a skin or membrane. Pierce potatoes, egg
yolks and chicken livers to prevent bursting.
MICROWAVE TECHNIQUES
Stirring:
Stir foods from outside to center of dish once or twice during cooking to equalize heat and speed microwaving.
Foods will not burn or stick, so there’s no need to stir constantly as you do in conventional cooking.
Arrangement:
Arrange foods with thin or delicate ends, like drumsticks or asparagus spears, with the thick or tougher
portions to the outside of the dish. The parts which need more cooking will receive more energy, so food will microwave
evenly.
Spacing:
Individual foods, such as baked potatoes and cupcakes will cook more evenly if placed in the oven an equal
distance apart. When possible, arrange foods in a circular pattern. Similarly, when placing foods in a baking dish, arrange
around the outside of the dish, not lined up next to each other. Food should not be stacked on top of each other.
Rearrangement:
Rearrange overlapping areas, like tails of long fish fillets, from top to bottom, and closely packed pieces,
like meatballs, from the outside to the center of the dish.
Standing Time:
Standing time is especially important in microwave cooking. Microwave energy creates heat in the outer
layers of the food. As a result of normal conduction, the food continues to cook for a few minutes after removal from the
oven. Letting roasts, large whole vegetables, casseroles and cakes stand to finish cooking allows the middles to cook
completely without overcooking, drying or toughening the outsides.
Covering:
Covering speeds cooking time, retains moisture, tenderizes, insures even cooking and prevents spattering.
Casserole lids or plastic wrap are used for a tighter seal. Vent plastic by turning back one edge at the side of dish to form
a narrow slot where excess steam can escape. Various degrees of moisture retention are also obtained by using wax
paper or microwave-safe paper towels.
Browning:
Microwave energy cooks some foods so quickly that the fats and sugars within the food do not have time to
caramelize and give a "browned" appearance. Browning agents do not affect the quality of microwaved foods, but can
add color and flavor. For meats and poultry, use bouquet sauce diluted with water or melted butter, soy, Worcestershire,
barbecue or steak sauce, a sprinkling of paprika or dry gravy mix; jelly glaze or crumb coating. Frosting and topping
finish cakes and breads. Top casseroles at the end of microwaving with grated cheese or crumbs.
COOKING GUIDE
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