Nutrient Loss 225
the pathways for nutrient losses will be discussed. In addition, factors that influence
the nutrient content of fresh fruits and vegetables and nutritional quality, as well
implications of produce processing, will be addressed.
8.2 OVERVIEW OF NUTRITIONAL VALUE OF PRODUCE
Fruits and vegetables are the major sources of dietary fiber, minerals, vitamins, and
other potentially beneficial compounds. In addition, they contribute water, carbohy-
drates (more in fruits than in vegetables, for the most part), and, to a smaller extent,
some protein and fats in selected products such as avocados and olives (Salunkhe
et al., 1991). Seeds and legumes are not the focus of this book, but these foods
would make more substantial protein and fat contributions than fresh fruits and
vegetables. Many fruits and vegetables are excellent sources of provitamin A, vitamin
C, vitamin E, magnesium, potassium, and folate as well as numerous biologically
active phytochemicals and dietary fiber (Broekmans et al., 2000). Phytochemicals
are defined as substances found in edible fruits and vegetables ingested by humans
daily in gram quantities that exhibit a potential for modulating human metabolism
(Jenkins, 2002). Table 8.1 lists the richest fruit and vegetable sources of specific
TABLE 8.1
Richest Fruit and Vegetable Sources of Selected Nutrient and
Nonnutrient Compounds
Substance Richest source
Vitamin C
Vitamin E
Folates
Vitamin K
Calcium, iron, magnesium
Potassium
Fiber, pectin, polysaccharides
Monounsaturated fatty acids
Alpha, beta-carotene
Beta-cryptoxanthin
Lutein
Lycopene
Flavonoids
Flavanoids
Anthocyanins
Glucosinolates
Alkenyl cysteine sulfoxides
Glycoalkaloids
Fouranocoumarines
Cyanogenic glycosides
Citrus and other fruits, green vegetables, potatoes
Vegetable oils, avocados
Green leafy vegetables, potatoes, oranges
Green leafy vegetables
Green leafy vegetables
Bananas, vegetables and fruits generally
Fruits and vegetables generally
Olive oil
Carrots, green leafy vegetables, yellow/orange fleshed fruits
Oranges and related fruits
Yellow/green vegetables
Tomatoes
Onions, apples, green beans
Peaches, strawberries
Red/purple berries
Brassicas
Alliums
Potatoes, aubergines
Parsnips, celery
Cassava, Prunus spp., butter beans