As a cook ,you have a choice of many kinds of vegetables and many cooking methods. Not surprisingly, then, you are also faced with the necessity of learning many rules for cooking vegetables. Cooking affects vegetables in four ways. It changes the following:
1. Texture.
2. Flavor.
3. Color.
4. Nutrients.
How much these four characteristics change determines whether your final product is attractive and delicious to the customer or whether it ends up in the garbage. You can control these changes if you understand how they happen.
Unfortunately, there is still legitimate controversy among chefs about proper vegetable cooking techniques. Modern technology has not yet solved all the problems that experienced chefs tackle successfully every day in the kitchen.
CONTROLLING COLOR CHANGES
It is important to preserve as much natural color as possible when cooking vegetables. Because many people may reject or accept a vegetable on the basis of its appearance, it can be said that its visual quality is as important as its flavor or nutritional value.
Pigments are compounds that give vegetables their color. Different pigments react in different ways to heat and to acids and other elements that may be present during cooking, so it is necessary to discuss them one at a time.
WHITE VEGETABLES
White pigments, called flavones, are the primary coloring compounds in potatoes, onions, cauliflower, and white cabbage and in the white parts of such vegetables as celery, cucumbers, and zucchini.
White pigments stay white in acid and turn yellow in alkaline water. To keep vegetables such as cauliflower white, add a little lemon juice or cream of tartar to the cooking water. (Don’t add too much, though, as this may toughen the vegetable.) Covering the pot also helps keep acids in.
Cooking for a short time, especially in a steamer, helps maintain color (and flavor and nutrients as well).Overcooking or holding too long in a steam table turns white vegetables dull yellow or gray.
RED VEGETABLES
Red pigments, called anthocyanins, are found in only a few vegetables, mainly red cabbage and beets. Blueberries also are colored by these red pigments.(The red color of tomatoes and red peppers is due to the same pigments that color carrots yellow or orange.) Red pigments react very strongly to acids and alkalis. Acids turn them a brighter red.
Alkalis turn them blue or blue-green (not a very appetizing color for red cabbage). Red beets and red cabbage, therefore, have their best color when cooked with a small amount of acid. Red cabbage is often cooked with tart apples for this reason.
When a strongly acid vegetable is desired, such as Harvard Beets or Braised Red Cabbage, add just a small amount of acid at first. Acids toughen vegetables and prolong cooking time. Add the rest when the vegetables are tender.
Red pigments dissolve easily in water. This means
1. Use a short cooking time. Overcooked red vegetables lose a lot of color.
2. Use only as much water as is necessary.
3. Cook beets whole and unpeeled, with root and an inch of stem attached, to protect color. Skins easily slip off cooked beets.
4. When steaming,use solid pans instead of perforated pans to retain the red juices.
5. Whenever possible, serve the cooking liquid as a sauce with the vegetable.
GREEN VEGETABLES
Green coloring, or chlorophyll, is present in all green plants. Green vegetables are common in the kitchen,so it is important to understand the special handling required by this pigment.
Acids are enemies of green vegetables. Both acid and long cooking turn green vegetables to a drab olive green.
Protect the color of green vegetables by
1. Cooking uncovered to allow plant acids to escape.
2. Cooking for the shortest possible time. Properly cooked green vegetables are tender-crisp, not mushy.
3. Cooking in small batches rather than holding for long periods in a steam table. Steaming is rapidly becoming the preferred method for cooking green vegetables. Steam cooks food rapidly, lessens the dissolving out of nutrients and flavor, and does not break up delicate vegetables. Overcooking, however, can occur rapidly in steamers.
Do not use baking soda to maintain green color. Soda destroys vitamins and makes texture unpleasantly mushy and slippery.
How much water should be used when boiling? A large quantity of water helps dissolve plant acids, helps preserve colors, and speeds cooking .But some cooks feel that an excessive amount of nutrients are lost. See the next section for further discussion.
YELLOW AND ORANGE VEGETABLES
Yellow and orange pigments, called carotenoids , are found in carrots, corn, winter squash, rutabaga, sweet potatoes, tomatoes, and red peppers. These pigments are very stable. They are little affected by acids or alkalis. Long cooking can dull the color, however.
Short cooking not only prevents dulling of the color but also preserves vitamins and flavors.
CONTROLLING NUTRIENT LOSSES
Vegetables are an important part of our diets because they supply a wide variety of essential nutrients. They are our major sources of vitamins A and C and are rich in many other vitamins and minerals. Unfortunately, many of these nutrients are easily lost.
Six factors are responsible for most nutrient loss:
1. High temperature.
2. Long cooking.
3. Leaching (dissolving out).
4. Alkalis (baking soda, hard water).
5. Plant enzymes (which are active at warm temperatures but destroyed by high heat).
6. Oxygen.
Some nutrient loss is inevitable because it is rarely possible to avoid all of these conditions at the same time. For example,
• Pressure steaming shortens cooking time, but the high temperature destroys some vitamins.
• Braising uses low heat,but the cooking time is longer.
• Baking eliminates the leaching out of vitamins and minerals, but the long cooking and high temperature cause nutrient loss.
• Boiling is faster than simmering, but the higher temperature can be harmful and the rapid activity can break up delicate vegetables and increase loss through leaching.
• Cutting vegetables into small pieces decreases cooking time, but it increases leaching by creating more exposed surfaces.
• Even steaming allows some leaching out of nutrients into the moisture that condenses on the vegetables and then drips off.