Contributions of Nonvolatile Phytochemicals to Nutrition and Flavor P. Perkins-Veazie and J.K. Collins ADDITIONAL INDEX WORDS. ascorbic acid, dietary fiber, folate, organoleptic, phytoestrogens, polyphenolics SUMMARY. Small fruit are rich in several types of phytochemicals, vitamins, and minerals. These compounds have health functional properties that may protect humans from cardiovascular disease and certain cancers. Several of these phytochemicals, such as dietary fiber, anthocya- nins, and polyphenolics, also contribute to small fruit quality. Other components contribute to appearance and taste. Nonvolatile organic acids contribute to the perceived sourness of small fruit and changes in levels can alter visual color by affecting cellular pH and anthocyanin structure. The soluble sugars glucose, fructose, and sucrose contribute directly to the perceived sweetness of the fruit and provide carbohydrates for other metabolic functions such as phe- nolic and ascorbic acid synthesis. mall fruit cover a range of flavors, from sour to sweet to ambrosial. Perhaps most noted for flavor are strawberries (Fragaria ×ananassa) and raspberries S(Rubus idaeus), which have powerful taste and aromatic notes. Other small fruit can range from primarily sour or astringent, such as cranberries (Vaccinium macrocarpon), to sweet with little character, such as many table grape (Vitis vinifera) varieties. The nonvolatile acids and sugars potentiate the flavor of volatile aroma compounds that impart the flavor notes associated with each fruit. Tannins provide the astringent or bitter notes often found in immature berries and the water soluble pigments of ripe fruit. Fruit texture depends on the amount of soluble and insoluble fiber, made up of pectins, cellulose, and hemicellulose. Until recently, small fruit were primarily perceived as dessert-type products, or for processing into juices and wines. The discovery of relatively high levels of antican- cer compounds such as the phenolic compound, ellagic acid, in small fruit (Daniel et al., 1989), and the finding that increased intake of fruit and vegetables reduced the incidence of cancer and coronary heart disease (Block et al., 1992; Kamei et al., 1995; Steinmetz and Potter, 1996) has sparked great interest in the consump- tion of small fruit for their health benefits. The objective of this review is to present the relationship between the health promoting phytochemicals and quality in small fruit. United States Department of Agriculture, Agriculture Research Service, South Central Agricultural Research Laboratory, Hwy. 3 West, Lane, OK 74555. 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G October–December 2001 11(4) 539 Workshop.2 539 9/5/01, 11:45 AM Phytochemicals from free radical damage to cells (Buettner, lar disease risk (Brouwer et al., 1999). nonvolatile sources in 1993). Vitamin C may also be used by An inadequate intake of folate by preg- the body to regenerate another impor- nant women increases the risk of neu- small fruit tant lipid soluble antioxidant, α-toco- ral tube defects in babies (Brouwer et Functional foods contain pherol (vitamin E) (Jacob, 1995). In- al., 1999; Czeizel and Dudas, 1992). phytochemicals, defined as the nutri- creased intake of vitamin C is corre- The Recommended Dietary Intake is tive or nonnutritive compounds found lated with a reduction in risks of stroke 400 µg·d–1 (1.4 × 10–5 oz) of dietary in plants that are associated with re- (Gey et al., 1993) and certain cancers folate equivalent (Food and Nutrition duced disease risk. Because of the nu- (Byers and Guerrero, 1995). Most Board, 2000). Small fruit especially tritive properties of fruit, the United small fruit contain moderate to high blackberries, strawberries, and rasp- States Department of Agriculture (2000) amounts of vitamin C (Table 1). Ascor- berries, provide a slight to moderate and the American Heart Association bic and dehydroascorbic acid are the (5% to 10%) source of dietary folate (2000) recommend three to five serv- two active forms of vitamin C. The (Table 1). ings of fruit per day. The most com- USDA-recommended dietary intake monly found nonvolatile phytochemicals of vitamin C was increased recently Dietary fiber in small fruit include ascorbic acid (vita- from 60 mg·d–1 (2.1 × 10–3 oz) to 75 Small fruit are a good source of min C), calcium, potassium, dietary fi- mg·d–1 (2.6 × 10–3 oz) for women and dietary fiber, primarily pectin. Dietary ber, folic acid, phytoestrogens, and phe- 90 mg·d–1 in men (3.2 × 10–3 oz), with fiber is defined as plant material that is nolic compounds (including anthocya- an additional 35 mg·d–1 (1.2 × 10–3 oz) resistant to digestive enzymes in hu- nins and tannins) (Tables 1 and 2). A list recommended for smokers (Food and mans and is divided into two groups of the reported effects of these phyto- Nutrition Board, 2000). Horticultural based upon solubility in water (Brown chemicals on human health is given in studies involving small fruit often over- et al., 1999). Insoluble fibers consist Table 3. Even though a single phy- look the analysis of this important vita- of cellulose and lignin and some hemi- tochemical has health properties, small min, although postharvest studies have cellulose fibers. Soluble fibers include fruit are comprised of a mixture of shown losses of this vitamin in small some hemicelluloses, gums, mucilages phyto-chemicals, some in minute fruit held for short durations at tem- and pectins, which are natural gel form- amounts, which may result in a more peratures greater than 5 °C (41 °F) ers. Soluble fibers, including pectins, powerful and synergistic effect on dis- (Lee and Kader, 2000). have been reported to lower choles- ease prevention than larger amounts terol levels in humans, although the of one phytochemical. Folate results have varied as to the extent of Folate (folic acid) a B-vitamin the cholesterol lowering properties Vitamin C found in fruit, vegetables and grains, (Brown et al., 1999). The mechanisms Vitamin C serves as a cofactor for acts as a coenzyme in the body and involved in this biological action are many enzymes controlling functions may lower homocysteine levels (Tucker not yet determined; one hypothesized in the human body and is a powerful et al., 1996). Lower homocysteine lev- action is that cholesterol and fatty acid water soluble antioxidant that prevents els are reported to reduce cardiovascu- excretion is increased with a high in- Table 1. Nutrient composition of calories, dietary fiber, calcium, potassium, vitamin C and foliate of small fruit on a per cup basis (USDA, ARS, 2001). Nutrient composition 1 cup wt Calories Dietary fiber Calcium Potassium Vitamin C Folate Fruit (g)z (×1000)y (g) (mg) (mg) (mg) (µg) Blackberry (Rubus sp.) 144 74.9 7.6 46.1 282.2 30.2 49.0 Blueberry (Vaccinium sp.) 145 81.2 3.9 8.7 129.1 18.9 8.7 Boysenberries, canned (Rubus sp.) 132 66.0 5.1 35.6 183.4 4.1 83.6 Cranberry (Vaccinium macrocarpon) 110 53.9 4.6 7.7 78.1 14.9 2.2 Currant, black (Ribes nigrum) 112 70.6 NA 61.6 360.6 202.7 NA Currant, red or white (Ribes rubrum) 112 62.7 4.8 37.0 308.0 45.9 9.0 Elderberries (Sambucus canadensis) 145 105.9 10.2 55.1 406.0 52.2 8.7 Loganberries (Rubus sp.) 147 80.9 7.2 38.2 213.2 22.5 37.8 Raspberry (Rubus idaeus) 123 60.3 8.4 27.1 187.0 30.8 32.0 Strawberry (Fragaria ×ananassa) 152 45.6 3.5 21.3 252.3 86.2 27.4 Table grape (Vitis vinifera) 160 113.6 1.6 17.6 296.0 17.3 6.4 Table grape (Vitis labrusca) 92 61.6 0.9 12.9 175.7 3.7 3.6 Gooseberries (Ribes sp.) 150 66.0 6.5 37.5 297.0 41.5 9.0 Recommended daily intakex Men --- 2000 25 1000–1300 3500 90z 400 Women --- 2000 25 1000–1300 3500 75z 400 z28.35 g = 2.835 × 104 mg = 2.835 × 107 µg = 1.0 oz. y1000 calories = 4.19 kJ. xRecommended that smokers take in an additional 35 mg·d–1 of vitamin C. 540 G October–December 2001 11(4) Workshop.2 540 9/5/01, 11:45 AM take of soluble fiber. Another action kidney stone formation (Ettinger et Phenolics may be that the mere replacement of al, 1997; Sacks et al., 1998). The cholesterol-laden and fatty foods with USDA recommended dietary intake Small fruit are a good source of phe- that of fiber-rich foods in the diet is for potassium is 3,500 mg·d–1 (0.12 nolic compounds, comprised primarily of responsible for the reduction in cho- oz) (Food and Nutrition Board, 2000). anthocyanins, proanthocyanins, flavonols, lesterol levels (Lampe, 1999). Dietary Calcium helps maintain the structure flavan-3-ols and phenolic acids (Table 4) fiber from foods also seems to be pro- of bones and teeth, and is needed for (Kalt et al., 2001).