1. Microwaves

2. History of Microwaves In 1945, Dr. Perry Spencer, a scientist, was working in a lab when he felt some heat on his hand. The heat was coming from microwaves. These were being emitted from a nearby vacuum tube. Dr. Spencer was curious and place a chocolate bar near the tube. Within seconds, the chocolate melted. That sticky mess was the beginning of a brilliant idea – the microwave!

3. Diagram of a Microwave

4. How Does a Microwave Work? The microwave oven generates electromagnetic waves (called microwaves) which makes water move. This motion leads to friction, and friction leads to heating. motion frictionheating

5. How Does a Microwave Work? This heat starts on the outside of the food and moves in. The denser the food the longer it will take to cook. –Water will heat faster than a burrito, because a burrito is more dense than water. –The outer edges cook first. For even cooking, stir the edges.

6. Energy comes from some source: gas flame, burning charcoal or electricity. In a microwave oven the energy is electromagnetic which goes through a magnetron tube making microwaves.

7. Microwaves cause the moisture molecules in the food to vibrate at a fantastic rate. This creates friction which is heat and this is what cooks the food. You can feel the same kind of heat made by friction by rubbing your hands together.

8. Microwaves are “non-ionizing”, they do not cause chemical change such as X-rays do. The microwaves cause the food to cook itself rather than being cooked by an outside source.

9. The microwave oven has three basic uses: 1. cooking. 2. defrosting. 3. reheating.

10. Defrosting. When defrosting in the microwave, alternate cooking times and standing times. Standing time allows heat to move towards the center of the food to defrost evenly. If you just use one long continuous coking time the outside will cook and the inside will still be frozen.

11. Microwaves are… Microwaves are: 1. absorbed 2. reflected 3. transferred The microwaves should transfer through the container, absorb into the food and be reflected off the sides, top, and bottom of the oven to go through the process again.

13. It is TIME not temperature that is important. The time depends on: 1. Starting temperature 2. Volume. 3. Density

14. Time. Starting temperature- The colder the food the longer it will take to cook. Volume- As the volume of the food increases, the cooking time increases. Example: It takes 4-6 minutes to cook 1 potato 8-11 minutes to bake 2 potatoes, and 16-19 minutes to bake 4 potatoes Density- The more dense the food is, the longer it takes to defrost.

15. Food continues to cook after being taken out of the microwave Oven, so a standing time is needed before eating. It can just be a few seconds. The more the food, the longer the time. The temp. gets hotter as it stands. Example: Bake a medium potato for 4 minutes. It is still firm. After it stands for a few minutes it will be soft and ready to eat.

16. Arrange the food so there is space in between the food. (Such as potatoes) Put the thicker part of the food towards the outside. Arranging the food.

17. Microwaves Microwaves are attracted to foods that are high in: water fat sugar

18. Microwave-able Containers Paper Plastic Glass Microwaveable Dishes

19. Non-Microwave-able Containers Metal Dishes with gold or silver on it.

20. Acceptable coverings for microwave dishes: Paper towel – to absorb moisture, spatters, and spills. Wax paper – holds in some of the moisture Plastic wrap – hold in moisture The test to know if you can use a container is: put a glass of water in the middle of it and heat for 1 minute. If the plate heats before the water, the plate cannot be used.

21. Cleaning the microwave Wipe it out with dish detergent and water. You can use any gentle all-purpose spray cleaner. Odors can be removed by boiling a cup of lemon juice and water. Microwave cooking saves 75% of electricity and time as compared to conventional cooking. You can cook faster and in less water so you retain more nutrients. Microwave cooking is safe and convenient. It is easy and takes no special skill.

22. Techniques for Microwaving Stirring: To pull heated part of the food to the center Turning over: To microwave all sides Rotating: Makes cooking even Pricking: To keep foods from exploding Standing Time: To allow foods to complete its cooking by placing on the counter.

23. Cooking Time These will increase the cooking time and standing time. –The volume of the food Example: Small potatoes versus large potatoes –The quantity or number of food –Round containers will cook more evenly than square containers.

24. Microwave Safety To prevent burning yourself from microwave cooking, remember: –Foods can create hot containers –Items that can explode (eggs, potatoes). Pierce them with a fork. –Lifting the cover or plastic from the food can cause a burn. –Hot steam escaping can cause a burn

25. What foods should not be microwaved?