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8.3.2 PIGMENTS
In addition to flavor compounds, fruits and vegetables also contain a variety of
pigments, some of which will be discussed in greater detail in section 8.3.3 (Phy-
tonutrients). Garden beets owe their characteristic red color to betacyanin, which
strongly overshadows the yellow pigment betaxanthin also found in beets (Roy and
Chakrabarti, 1993). Other pigments such as chlorophyll, carotenoids, and anthocy-
anins are responsible for the color of other fruits and vegetables. Chlorophyll pro-
vides the green color of most green vegetables and fruits (e.g., spinach and apples),
while carotenoids provide the orange color of citrus fruit, apricots, and peaches, and
lycopene the red color of tomatoes. Anthocyanins provide the naturally red, blue,
or purple colors of sweet potatoes, apples, plums, grapes, and strawberries (Roy and
Chakrabarti, 1993). These pigments have been shown to have a potential role in
disease prevention; lycopene from tomatoes has been suggested to help prevent
prostate cancer (Bowen et al., 2002; Hadley et al., 2002; Kucuk et al., 2002;
Giovannuci et al., 1999) and anthocyanins from tart cherries have been posited as
antioxidants and anti-inflammatory agents (Wang et al., 1999).
8.3.3 PHYTONUTRIENTS
For the past 20 years, we have heard that fruits and vegetables are the cornerstone
of health, supplying us with a wealth of vitamins, minerals, fiber, and complex
carbohydrates. More recently, scientists have found another group of compounds
within fruits and vegetables, phytonutrients or phytochemicals, which occur naturally
in plants. Phytonutrients are biologically active organic substances in plants that
give them their color, flavor, odor, and protection against plant diseases. During the
past few years, scientists have discovered that many of these plant chemicals may
also promote human health and protect the body against diseases (Van Duyen and
Pivonka, 2000). Studies have consistently found that eating greater amounts of fruits
and vegetables may reduce the risk of heart attacks, macular degeneration (the chief
cause of blindness in adults), and most cancers (Gillman et al., 1995; Voorrips et
al., 2000; Riboli and Norat, 2003). Unlike the traditional nutrients (protein, fat,
vitamins, and minerals), phytonutrients are not “essential” for life; thus, some sci-
entists prefer to call them phytochemicals. Phytonutrients are classified into
11 classes, some of which contain hundreds of different phytochemicals: carotenoids
(e.g., carotene, α-, β-, γ-carotene, lutein, lycopene, zeaxanthin, β-cryptoxanthin, and
capsanthin); dietary fiber; glucosinolates, indols, and isothiocyanates; inositol pho-
phates; polyphenols (e.g., flavonoids, isoflavones, anthocyanidins, and catechins);
phenol and cyclic compounds (e.g., terpenes); phytoestrogens; plant sterols; protease
inhibitors; saponins; and sulfide- and thiol-containing compounds (e.g., sul-
phoraphane and allylic sulfides). Phytochemicals are found in a variety of foods
such as onions, garlic, leeks, celery, apples, cranberries, raspberries, blueberries,
some nuts such as almonds, red wine, tea, peppers, parsley, spinach, chives, broccoli,
cabbage, kale, cauliflower, soybeans, tomatoes, citrus fruits, carrots, brussels sprouts,
turnips, papaya, pineapples, whole grains, grapes, beans, legumes, cherries, straw-
berries, sweet potatoes, peaches, apricots, watermelons, guavas, and pumpkin
(Salunkhe et al., 1991; Van Duyen and Pivonka, 2000).