Often we become creatures of habit – preparing and cooking vegetables the same way our mothers and grandmothers did. While good cooking never goes out of style, cooking methods and preferences do change. Today, slow cooking and microwaving offer cooking at both extremes: very slow and very fast.
Slow cooking uses a countertop electric appliance called a slower cooker. The slow cooker is made up of a ceramic or porcelain pot (which retains heat) set into a metal housing containing the electric heating element. It’s best to buy a slow cooker with a removable pot, which is easier to clean, and a glass lid, which makes it easier to check on the meal’s progress. In slow cooking, heat surrounds the food, which cooks at a low temperature – about 77° – 138°C (170° – 280°F) for anywhere from about five to twelve hours. The big advantage of using a slow cooker is that you can prepare a meal in the morning, turn on the slow cooker, and when you come home from work, dinner is ready. Slow cooking is also great because its low temperature saves energy and retains nutrients. Good meals for the slow cooker are soups, stews, spaghetti sauce, and dried bean dishes.
Microwave cooking is a good way to cook fresh vegetables: it’s quick and retains nutrients and fresh flavour. Jacket potatoes and winter squash can be microwaved in just a few minutes. Microwaves are good at cooking foods with a high water content – which includes vegetables. Microwaved vegetables taste a lot like steamed vegetables.
How do Microwaves Work?
Microwaves are high frequency electromagnetic waves – like TV and radio waves. The microwaves are generated by a tube called a magnetron and are scattered about by a reflector called a stirrer. Microwave ovens are lined with metal that reflect the microwaves and cause them to bounce around like ping pong balls, vibrating at 2,450 million cycles per second.
Food absorbs microwaves, which cause the liquid molecules in the food to vibrate rapidly – the heat caused by this friction cooks the food. One misconception about microwave cooking is that it “cooks from the inside out”. Actually, it cooks from just beneath the surface of the food inward and then back outward again, repeating this cycle over and over. It cooks essentially like conventional conduction cooking methods.
Microwaves can pass through glass ‐ much like light waves in sunlight can pass through window glass ‐ as well as ceramic, paper, and plastic. That’s why containers used for microwave cooking are made of these solid materials ‐ they don’t absorb the heat.
Are Microwaves Safe?
One thing to keep in mind is that microwave radiation is in the non‐ionizing (lower) range of the electromagnetic spectrum, lower than waves in the ionizing range which do contain dangerous radiation. Even so, with today’s microwave ovens the possibility of any radiation leakage is unlikely, although people with pacemakers should use extra caution.
Most people know not to use metal containers or tin foil in the microwave as it can cause arcing – sparks flying between the metal container and the metal wall of the microwave. But did you know that arcing can sometimes occur when microwaving certain vegetables? The minerals in string beans, carrots, peppers, and some other dense vegetables can cause sparks which result in brown spots on the vegetables. This doesn’t hurt the food, but it can interfere with it heating through properly.
One current controversy is whether using plastic containers in the microwave poses a health hazard. One urban legend that’s circulated on the Internet for years is that plastics contain dioxins which are released in food when heated in the microwave. Plastics do not contain dioxins.
Plastics do contain a chemical called diethylhexyl adipate (DEHA), a plasticizer that makes plastics flexible. Although DEHA is considered safe for use with food, some of it can leach into the food if it comes into direct contact – not a good idea. With that in mind, here are a few safety tips for using plastics in the microwave:
- Keep a 2.5 cm (one inch) space between the plastic covering and the food being heated.
- Use only plastic containers labeled as “microwave safe” or that contain instructions for microwave use.
- Don’t reuse plastic food containers such as margarine tubs or restaurant take‐away containers to heat foods in the microwave. They may warp or melt.
The advantages of microwave cooking: one, it’s fast – cooking vegetables in a quarter to half the time it takes using conventional methods. Two, since it’s fast, it retains more vitamins and minerals. Three, it saves money over using a regular oven – microwaves use about a quarter of the energy.
Note that cooking frozen vegetables in the microwave is not recommended: it’s very inefficient. Since the microwave has to melt the frozen water molecules to a liquid state before they can move around and cook, it takes a long time to cook frozen vegetables in a microwave – you’re better off steaming them.
Why not take a new approach to cooking vegetables and try slow cooking and microwaving?