Q 547 quercetin A widely distributed plant pigment that is classified as a FLAVONOID. It is found in fruits like APPLES, vegetables like ONIONS, and in TEA. A typical Western diet supplies about 25 mg of quercetin daily. Onions, apples, kale, sweet cherries, grapes, red cabbage, and green beans are good sources. Quercetin produces a broad range of effects in the body. It can function as an ANTIOXIDANT to quench highly reactive chemicals called FREE RADICALS. Together with VITAMIN C, quercetin helps strengthen fragile capillaries and connective tissue. It can inhibit tumor formation and modulate enzymes in the liver that degrade drugs, pollutants, and cancer-causing agents. Quercetin can reduce inflammation by blocking the formation and the release of inflamma- tory agents, and it possesses antimicrobial activity as well. (See also PHYTOCHEMICALS.) quince (Cydonia cydonia) A yellow, pear-shaped FRUIT harvested from the cydonia tree, native to Iran and the Caucasus. The flesh is hard and extremely tart, preventing it from being eaten raw. Quince contains high levels of pectin, a gel-form- ing fiber. It is used in marmalades, jellies, jams, fruit preserves, and syrup as a thickening agent. One quince (151 g) provides 53 calories; protein, 0.37 g; carbohydrate, 14 g; fiber, 1.6 g; potassium, 181 mg; vitamin C, 14 mg; thiamin, 0.018 mg; riboflavin, 0.028 mg; niacin, 0.18 mg. (See also CIT- RUS FRUIT.) quinoa (chenopodium) A grain-like product unrelated to true grains. A cousin to spinach and swiss chard, quinoa produces edible greens in addi- tion to its seeds, which form large clusters at the end of the stalk. Domesticated and grown in South America for 5,000 years, quinoa was cultivated by the Incas. This hardy plant grows well at high ele- vations that experience little rainfall. Quinoa is imported from South America. Domestic supplies come from the Rocky Mountain region (Colorado). The seeds are protected by a resin-like layer (saponin), which must be removed by treatment with alkali to be edible. The cleansed grain resembles millet. Quinoa has a high protein content. Quinoa protein is well balanced in essen- tial AMINO ACIDS and has substantial amounts of lysine, unlike cereal grains. Quinoa also contains more iron than other grains and contains substan- tial amounts of other trace minerals and calcium, as well as B complex vitamins. The cooking time for quinoa is shorter than for rice or millet. Its del- icate taste combines well with other grains in pilaf or baked grain casseroles. The nutrient content of 3.5 oz. (100 g) of dry grain is 374 calories; protein, 13 g; carbohydrate, 69 g; fat, 6 g; potassium, 740 mg; iron, 9 mg; thi- amin, 0.2 mg; riboflavin, 0.4 mg; niacin, 3.0 mg. quinone A family of lipids that readily undergo oxidation-reduction reactions. Two important quinone derivatives occur in the body: VITAMIN K and COENZYME Q. Vitamin K serves as a cofactor in the synthesis of several proteins required for BLOOD CLOTTING , while coenzyme Q functions as an elec- tron carrier in MITOCHONDRIA, the cell’s power- houses. Coenzyme Q participates in the transfer of electrons to convert OXYGEN to water. At the same time ENERGY is trapped as ATP, a chemical form used by the cell. (See also ELECTRON TRANSPORT CHAIN; OXIDATIVE PHOSPHORYLATION.) quorn A meat substitute made from the fungus Fusarium venenatum. To make quorn the fungus is grown in large fermentation vats, producing a microprotein. The substance is then spun at high velocity in a centrifuge to remove water. The remaining material (quorn) is then mixed with other ingredients, including flavor enhancers and egg whites, to create a substance that looks and tastes like meat. Pound for pound, quorn contains fewer calories and less saturated fat and cholesterol than do chicken or beef. Quorn has been sold in Great Britain since 1985 and has become the most popular meat substitute in Europe. In 2001 the U.S. FDA allowed quorn to be marketed to U.S. consumers as a “generally rec- ognized as safe” (GRAS) food. Since then some consumer groups have raised concerns about the labeling and safety of quorn. Critics say that state- ments on quorn products that claim it is derived from the “mushroom family” are false and mis- leading. Some consumers have reported allergic and other adverse reactions to eating quorn. One serving of quorn “chicken” nuggets (100 g) pro- vides 212 calories; protein, 9.4 g; fat, 9.4 g; choles- terol, 0 g. Miller, S. A., and J. T. Dwyer. “Evaluating the Safety and Nutritional Value of Mycoprotein,” Food Technology 55, no. 7 (2001): 42–47. 548 quorn . enzymes in the liver that degrade drugs, pollutants, and cancer-causing agents. Quercetin can reduce inflammation by blocking the formation and the release of inflamma- tory agents, and it possesses. VITAMIN K and COENZYME Q. Vitamin K serves as a cofactor in the synthesis of several proteins required for BLOOD CLOTTING , while coenzyme Q functions as an elec- tron carrier in MITOCHONDRIA, the. cereal grains. Quinoa also contains more iron than other grains and contains substan- tial amounts of other trace minerals and calcium, as well as B complex vitamins. The cooking time for quinoa is