Dietary fiber constituents of selected fruits and vegetables.

This study compared the dietary fiber (DF), neutral detergent fiber (NDF), cellulose, hemicellulose, lignin, and pectin content of selected fruits and vegetables. Apples and peaches (fresh and canned), oranges (fresh), strawberries (fresh, canned, and frozen), carrots, green beans, and potatoes (fresh, fresh cooked, canned, and frozen), and tomatoes (fresh, fresh cooked, and canned) were studied. When possible, two varieties, two stores, and name and store brands were chosen. Samples were analyzed for NDF, acid detergent fiber, 72% sulfuric acid, lignin, and pectin. From those values, DF, cellulose, and hemicellulose were calculated. Fresh fruits in gm/100gm wet weight had decreasing DF, NDF, and hemicellulose values as follows: apples, peaches, strawberries, and oranges. Apples were highest in cellulose; strawberries, highest in lignin; and oranges, highest in pectin. Fresh-cooked vegetables in gm/100gm wet weight have decreasing DF and NDF values as follows: green beans, carrots, potatoes, and tomatoes. Green beans were highest in cellulose and hemicellulose; potatoes highest in lignin; and carrots highest in pectin. On a wet-weight basis, fresh apples and peaches, fresh-cooked green beans, canned carrots, and canned and frozen potatoes were higher in DF and NDF than other forms of the fruit or vegetable. There were few differences according to stores, brands, or varieties of fruits and vegetables. On a dry-weight basis, fresh apples, peaches, strawberries, green beans, and tomatoes appear to have higher DF and NDF contents than their processed counterparts. Fresh-cooked carrots and fresh potatoes appear to have less DF and NDF than their canned and frozen counterparts.