Microwave Cooking The Basics

Who invented the Microwave? Dr. Percy Spencer (a scientist) 1945 Discovered heat coming from a vacuum tube Melted a chocolate bar

How does it work? Magnetron changes electricity to microwaves that pass through waveguide Microwaves hit walls and bounce back to food Causes food molecules vibrate Penetrates food 1 ½” Stirrer blade circulates microwaves Metal, wire mesh door so you can see in but microwaves can’t get out Fan cools magnetron

Why use microwave cooking? Fast, healthful way to cook Cooks quickly with less fat and liquid Retains more water soluble vitamins (B, C) Fewer vitamins destroyed by heat

Power Settings Power ratings based on watts (units of electrical power) Compact units= watts Midsize to large= 800-1,000 Ratings found on back of oven

Power Settings MICROWAVE POWER LEVELS DESCRIPTIONPERCENTAGE OF POWER High100 Medium-High70 Medium50 Medium-Low30 Low10 Fill 1-cup liquid measurer with cold water- use thermometer to record temperature before and after 1 minute of cooking on various power levels

How to use the Power Levels Press ‘Time Cook’ on microwave Enter cooking time desired (for test use 1 minute or 1:00) Next press ‘Power Level’ and enter the power desired (1, 3, 5, 7) Press ‘start’ Simply press minutes and start for 100% or full power

Foods Relative to Cooking Time Composition- Foods higher in water content cook faster Vegetables vs. meats Density- dense (heavy) food takes longer Shape and Size- thin faster than thick Starting Temperature of Food Amount of Food- more takes longer (1 potato vs. 4 potatoes)

Foods Relative to Cooking Time Fat, Sugar, Salt- attract microwaves and create ‘hot’ spots Jelly doughnuts Salt foods after cooking Pasta and Rice- need time to absorb liquids as they cook (no real time is saved with microwave over conventional) Tough skinned foods- trap moisture, builds steam, might explode (potato)

Microwave Cookware Microwaves reflected by metals (arc)- can damage oven or start fire Pass through glass, plastic and paper Use shallow pans with straight sides- round or square with rounded edges

Microwave Cookware Glass and ceramic- Must be oven-proof Stoneware, china, pottery- no metal trim or metallic glaze Plastic- only microwave safe Paper- do not use recycled paper (may contain chemicals or metal fragments)

Testing Cookware If a glass or pottery container isn’t marked “microwave-safe”- Fill a glass measuring cup with water Place in microwave oven inside the empty container you are testing Heat for 2 minutes at 100 percent power (or until liquid boils) If empty container is too hot to touch it is not microwave safe

Successful Microwave Cooking Food Placement- Ring shape allow microwaves to enter food from many sides as possible Leave space between foods Use ‘spoke’ pattern Thin/tender parts inside Thick/tough parts outside

Successful Microwave Cooking Covering Food- Holds steam Shortens cooking time Keeps food moist Prevents spattering Use- Wax paper/parchment Paper Towels- prevents sogginess Loose fitting lids or inverted plate

Successful Microwave Cooking Stir, Rotate, Turn Food- Prevents uneven distribution of microwaves resulting in uneven cooking Marshmallow ‘hot spot’ test

Successful Microwave Cooking Cooking Time = 2 parts 1. Actual minutes cooked 2. “Standing time”- period which heat buildup in a microwave food completes its cooking time Check doneness after “standing time”

Well-Written Microwave Recipes Same features as a conventional recipe Should also include: Size and shape of cooking container How to arrange food for even cooking Whether or not to cover dish Range of cooking and standing times

Microwave Accident Prevention Never turn oven on unless there is food in it Follow instructions on prepared foods Loosen tight fitting lids to prevent explosions Never attach kitchen magnets to microwave- can affect electronic controls Have oven tested for leakage

Microwave Care Clean spots and spills after every use Food build up will absorb microwaves and cut down on cooking power

Answer the following Questions 1. What is a watt? 2. Why do vegetables cook faster in the microwave than meat? 3. Name two food ingredients that can cause hot spots. 4. Name two factors you should consider when deciding how much time food will take to cook in the microwave. 5. How should food be arranged in microwave for best cooking results? 6. What is standing time? 7. Why should you pierce tough skinned foods first? 8. What happens if dirt or food builds up in microwave?

Microwave Lab using Power Settings MICROWAVE Time-cook for 1 minute using each POWER LEVEL Power Setting Water Temperature Before Water Temperature After Difference High (100%) Medium-High (70%) Medium (50%) Medium-Low (30%) Low (10%) Fill 1-cup liquid measurer with cold water- use thermometer to record temperature before and after 1 minute of cooking on various power levels