Fiber sources

Com as com flakes, sweet com, com as various types of flour and meal, popcorn, other snacks foods such as chips, and com juice as sweeteners, com used in fermentation for beer and in the production of alcohol, and corncobs and stalks used as carriers for various chemicals and medications, as fiber sources, and for the improvement of soil condition by plowing under stalks, are some of the uses for this versatile crop. See Ref. 75 for more information on corn. 

Fibers and Fiber Sources. Fibers are present ia varyiag amounts ia food iagredients and are also added separately (see Dietary fiber). Some fibers, including beet pulp, apple pomace, citms pulp, wheat bran, com bran, and celluloses are added to improve droppiags (feces) form by providing a matrix that absorbs water. Some calorie-controUed foods iaclude fibers, such as peanut hulls, to provide gastroiatestinal bulk and reduce food iatake. Peanut hulls normally have a high level of aflatoxias. They must be assayed for aflatoxia and levels restricted to prevent food rejection and undesirable effects of mycotoxias. 

Other Insoluble Fiber Sources. Other iasoluble fiber sources are commercially avaUable as weU, including fiber from sugar-beet pulp, a by-product of sugar productioa. Table 3 Usts other iasoluble fiber sources. 

Two metabolic balance studies conducted in our laboratory have yielded information relative to the effect of phytate and dietary fiber on calcium bioavailabilty. In the first study, a relatively high intake of dietary fiber was consumed with a 10-fold difference in phytate intake from wheat bran. In the second study three levels of phytate were consumed with a low amount of dephytinized bran as the principal dietary fiber source. The two higher phytate levels in the latter study were attained using sodium phytate. 

Wheat bran has been the fiber source most commonly used to study effects of dietary fiber on calcium absorption in controlled laboratory studies. However, wheat bran and other forms of fiber as they occur in food products present several disadvantages in terms of definition and by concurrently altering intakes of other substances or materials known or suspected of having an adverse effect on the bioavailability of calcium such as phytates and oxalates (5,13,17,22-28). Several studies have been conducted which have sought to separate or compare the effects of phytate and fiber... 

In a series of human studies at the University of Nebraska, a total of 285 human adults were fed several different fiber sources during experimental periods of 5 to 7 days each. Some subjects received more than one test fiber treatment however, all subjects received at least one fiber source as well as receiving the controlled basal diet during one period which included no added fiber... 

Addition of bran from hard red and soft white wheat bran, psyllium fiber, and cellulose resulted in increased losses of calcium in feces in comparison to losses when no fiber supplements were used (P<0.05). Urinary calcium losses were not significantly affected however, calcium balances were lowered when these four fiber sources were added to the laboratory controlled diet (P < 0.05). 

In several studies (e.g., 30-36, Table I), the effects of including "processed" fiber sources (fiber isolated from natural sources) have been investigated. Results have been contradictory for example, lOgm/day cellulose decreased zinc balances in one study (3.0) but 30 to 40g/day did not affect zinc absorption in another study (36). Processed fiber may have effects which are not indicative of the effect of a similar level of endogenous fiber from foods. In summary, daily intake levels of fiber equivalent to 20 to 30g NDF/day from food sources would not be expected to have long-term deleterious effects on mineral utilization. 

Few differences were attributed to roasting of the navy bean hulls however, color of the hulls improved with heat treatment. Cakes prepared with either unheated or roasted bean hulls compared favorably to the control. Consequently, navy bean hulls are an acceptable source of dietary fiber in a flavored cake. More research should be initiated to investigate alternative uses for navy bean hulls as a dietary fiber source. 

The pulp and paper industries use three types of raw materials, namely, hard wood, soft wood, and nonwood fiber sources (straw, bagasse, bamboo, kenaf, and so on). Hard woods (oaks, maples, and birches) are derived from deciduous trees. Soft woods (spruces, firs, hemlocks, pines, cedar) are obtained from evergreen coniferous trees. 

Figure 17.1 U.S. production of fibers. (Source Chemical and Engineering News, Chemical and Economics Handbook, and the U.S. Department of Agriculture/Foreign Agriculture Service)...

Fiber, including Psyllium seed husks (a fiber source)... 

If the question of fiber composition is recognized by both the manufacturer and the user, the choice of a fiber furnish which has the necessary qualities is achieved by agreement. When the fiber source is unknown to the purchaser, a fiber analysis is a necessary requirement. Procedures for fiber analysis are well standardized and reliable—e.g., TAPPI standard T401 (3) and ASTM D1030 ( 4). 

The five leading states for final paper production are Wisconsin, Maine, Washington, Alabama, and Louisiana. Only a small amount of paper is made from rags or other fiber sources (agricultural residues) so most wood pulp is produced from those areas of the... 

Bagby MO, Nelson GH, Helman EG, Clark TF (1971) Determination of lignin in non wood plant fiber sources Tappi 54 1876-1878... 

Wheat bran contains several different forms of dietary fiber including hemicellulose. Some but not all purified dietary fiber sources have been found to have an adverse effect on manganese bioavailability (10). 

In our laboratory, the comparative effects of supplementation of a laboratory controlled vegetarian diet with three different fiber sources was examined when fed to omnivore and vegetarian subjects (14,15). 

Materials. Book papers dating from about 1790 to 1983 and provided by the Library of Congress were used. The book documents were selected at approximately 10-year intervals and are listed in Table I. Whatman filter paper was used as a cellulosic sample. The fiber sources of the paper documents were determined by a staining technique developed by Graff (5). The aluminon test (6) and Raspail test (7) were performed to determine the presence of alums and rosins, respectively, in paper documents. For comparison purposes, pH values of paper documents were obtained by cold-distilled-water extraction of 1 g of paper for 1 h. 

---