Energy value (calories per serving): Low
Saturated fat: Low Cholesterol: None Carbohydrates: High Fiber: High
Major vitamin contribution: Vitamin C (low)
Major mineral contribution: Potassium (low)
About the Nutrients in This Food
Eggplant is a high-fiber food with only minimum amounts of vitamins and minerals. One cup (100 g/3.5 ounces) boiled eggplant has 2.5 mg dietary fiber and 1.3 mg vitamin C (2 percent of the R DA for a woman, 1 percent of the R DA for a man).
In 1992, food scientists at the Autonomous University of Madrid studying the chemistry of the eggplant discovered that the vegetable’s sugar content rises through the end of the sixth week of growth and then falls dramatically over the next 10 days. The same thing happens with other flavor chemicals in the vegetable and with vitamin C, so the researchers concluded that eggplants taste best and are most nutritious after 42 days of growth. NOTE : Eggplants are members of the nightshade family, Solanacea. Other members of this family are potatoes, tomatoes, and red and green peppers. These plants produce natural neurotoxins (nerve poisons) called glycoalkaloids. It is estimated that an adult would have to eat 4.5 pounds of eggplant at one sitting to get a toxic amount of solanine, the glycoalkaloid in eggplant.
The Most Nutritious Way to Serve This Food
The eggplant’s two culinary virtues are its meaty texture and its ability to assume the flavor of sauces in which it is cooked. As a result, it is often used as a vegetarian, no-cholesterol substitute for veal or chicken in Italian cuisine, specifically dishes ala parmigiana and spaghetti sauces. However, in cooking, the egg- plant absorbs very large amounts of oil. To keep eggplant parmigiana low in fat, use non-fat cheese and ration the olive oil.
Buying This Food
Look for: Firm, purple to purple-black or umblemished white eggplants that are heavy for their size.
Avoid: Withered, soft, bruised, or damaged eggplants. Withered eggplants will be bitter; damaged ones will be dark inside.
Storing This Food
Handle eggplants carefully. If you bruise an eggplant, its damaged cells will release polyphe- noloxidase, an enzyme that hastens the oxidation of phenols in the eggplant’s flesh, produc- ing brown compounds that darken the vegetable.
Refrigerate fresh eggplant to keep it from losing moisture and wilting.
Preparing This Food
Do not slice or peel an eggplant until you are ready to use it, since the polyphenoloxidase in the eggplant will begin to convert phenols to brown compounds as soon as you tear the vegetable’s cells. You can slow this chemical reaction (but not stop it completely) by soaking sliced egg- plant in ice water—which will reduce the eggplant’s already slim supply of water-soluble vita- min C and B vitamins—or by painting the slices with a solution of lemon juice or vinegar.
To remove the liquid that can make a cooked eggplant taste bitter, slice the eggplant, salt the slices, pile them on a plate, and put a second plate on top to weight the slices down. Discard the liquid that results.
What Happens When You Cook This Food
A fresh eggplant’s cells are full of air that escapes when you heat the vegetable. If you cook an eggplant with oil, the empty cells will soak it up. Eventually, however, the cell walls will collapse and the oil will leak out, which is why eggplant parmigiana often seems to be served in a pool of olive oil.
Eggplant should never be cooked in an aluminum pot, which will discolor the eggplant. If you cook the eggplant in its skin, adding lemon juice or vinegar to the dish will turn the skin, which is colored with red anthocyanin pigments, a deeper red-purple. Red anthocyanin pigments get redder in acids and turn bluish in basic (alkaline) solutions.
Cooking reduces the eggplant’s supply of water-soluble vitamins, but you can save the Bs if you serve the eggplant with its juices.
Adverse Effects Associated with This Food
Nitrate/nitrite reactions. Eggplant—like beets, celery, lettuce, radish, spinach, and collard and turnip greens—contains nitrates that convert naturally into nitrites in your stomach, and then react with the amino acids in proteins to form nitrosamines. Although some nitrosamines are known or suspected carcinogens, this natural chemical conversion presents no known problems for a healthy adult. However, when these nitrate-rich vegetables are cooked and left to stand at room temperature, bacterial enzyme action (and perhaps some enzymes in the plants) convert the nitrates to nitrites at a much faster rate than normal. These higer-nitrite foods may be hazardous for infants; several cases of “spinach poisoning” have been reported among children who ate cooked spinach that had been left standing at room temperature.
MAO inhibitors. Monoamine oxidase (M AO) inhibitors are drugs used as antidepressants or antihypertensives. They inhibit the action of enzymes that break down tyramine, a natu- ral by-product of protein metabolism, so that it can be eliminated from the body. Tyramine is a pressor amine, a chemical that constricts blood vessels and raises blood pressure. If you eat a food rich in tyramine while you are taking an M AO inhibitor, the pressor amine can- not be eliminated from your body, and the result may be a hypertensive crisis (sustained elevated blood pressure). Eggplants contain small amounts of tyramine.
False-positive urine test for carcinoid tumors. Carcinoid tumors (tumors that may arise in tis- sues of the endocrine and gastrointestinal systems) secrete serotonin, which is excreted in urine. The test for these tumors measures the level of serotonin in your urine. Eating egg- plant, which is rich in serotonin, in the 72 hours before a test for a carcinoid tumor might raise the serotonin levels in your urine high enough to cause a false-positive test result. (Other fruits and vegetables rich in serotonin are bananas, tomatoes, plums, pineapple, avo- cados, and walnuts.)