Wheat fiber

TABLE 10.3 Effect of short and long fiber (wheat straw) on the coefficient of expansion-contraction of a polypropylene-based composite in the —40 to +25°C temperature range [3]... 

Presentations in this volume come from chemists, medical researchers, and microbiologists, as well as nutritionists and food scientists. In a few cases, rather exotic fiber types such as tobacco fiber, wheat straw lignin, or shellfish aminopolysaccharides are discussed. Other sources include psyllium, different legumes, and vegetable and fruit fibers. There is no doubt that additional unconventional fiber sources will be continuously identified and increasingly used. 

Table 17.1 presents the chemical composition of different vegetable fibers. Compared to the other fibers, wheat straw shows rather low cellulose content, a high lignin composition, but also a high ash content linked to a high silica fraction. Silica is mainly located on the leaves, 12% of ash in the leaves compared to, for example, 6% in the intemodes. Average value is 7-8% of ash in the straw. 

There are several different classifications in terms of plant fibers. While the classification of Nishino [59] includes seven groups as bast (soft) fibers (flax, hemp, jute), leaf (hard) fibers (sisal, abaca, pineapple, etc.), stem fibers (bamboo, banana stalk, corn stalk), fruit fibers (coconut), seed fibers (cotton, baobab, kapok), straw fibers (rice, wheat, corn), and others (seaweeds, palm), that of Faruk et al. [3] has six groups bast fibers (jute, flax, hemp), leaf fibers (abaca, sisal and pineapple), seed fibers (coir, cotton and kapok), core fibers (kenaf, hemp and jute), grass and reed fibers (wheat, corn and rice) and all other types (wood and roots). 

However, there are thousands of tons of agricultural wastes produced without proper utilization which found to be useful to prepare polymer composite for commercial purposes for example EFB, sisal fiber, wheat straw, and others (Abdul Khalil et al. 2012b). Numbers of natural cellulose fibers have been used to reinforce polymer composites. In fact, various types of natural fibers were investigated for incorporation in plastics. Basically, natural fibers are diverted into two categories which are wood and non-wood. Table 1 shows varieties of natural fibers that available on current research. 

Dietary fiber may influence lipidemia and atherosclerosis. Substances designated as insoluble fibers (wheat bran, for instance) possess laxative properties but have little effect on serum lipid levels. Soluble fibers (gel-forming fibers such as pectin or guar gum) influence lipidemia and glycemia. Oat bran, which contains /3-glucans, which are soluble fibers, will lower cholesterol levels despite its designation. 

Com, wheat, and rice are the most desirable common grains and are used extensively ia pet foods. Oats and barley often tend to have excess fiber, which can be objectionable. However, barley is a preferred grain for moisture absorption and form ia caimed foods because the turgid white form is desired ia some canned dog foods. Milo has enormous variations ia tannin content which can influence digestibiUty and acceptabiUty, thus limiting its use ia pet foods (see Wheat and other cereal grains). 

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. 

Potential resources of xylans are by-products produced in forestry and the pulp and paper industries (forest chips, wood meal and shavings), where GX and AGX comprise 25-35% of the biomass as well as annual crops (straw, stalks, husk, hulls, bran, etc.), which consist of 25-50% AX, AGX, GAX, and CHX [4]. New results were reported for xylans isolated from flax fiber [16,68], abaca fiber [69], wheat straw [70,71], sugar beet pulp [21,72], sugarcane bagasse [73], rice straw [74], wheat bran [35,75], and jute bast fiber [18]. Recently, about 39% hemicelluloses were extracted from vetiver grasses [76]. 

Seven diets were constructed from purified natural ingredients obtained from either C3 (beet sugar, rice starch, cottonseed oil, wood cellulose, Australian Cohuna brand casein, soy protein or wheat gluten for protein) or C4 foodwebs (cane sugar, corn starch, com oil, processed corn bran for fiber, Kenya casein for protein) supplemented with appropriate amounts of vitamins and minerals (Ambrose and Norr 1993 Table 3a). The amino acid compositions of wheat gluten and soy protein differ significantly from that of casein (Ambrose and Norr 1993). 

When compared to whole meal rye flour (280 kcal/1160 kJ) and to wheat flour (320 kcal/1320 kJ), phloem powder (140 kcal/580 kJ) contains approximately 50% less energy. As is typical for all flours, phloem powder also contains a low amount of fat (total amount 2.3 g/100 g). The protein content of phloem is only 2.5 g (per 100 g), whereas the respective amount in whole meal rye flour is 8.8 g and in wheat flour 12.1 g. The content of carbohydrates in phloem ( 30 g/100 g) is about 50% less than in rye (55 g) and wheat flours (59 g). The relatively low energy, protein and carbohydrate content of phloem when compared with commonly used flours, is related to its high content of different fiber. Detailed nutritional data for phloem and phloem breads used in our trial are presented in Table 14.1. 

TOPPING D L, ILLMAN R J, ROACH P D, TRIMBLE R P, KAMBOURIS A, NESTED P J (1990) Modulation of hypolipidemic effect of fish oil by dietary fiber in rats studies with rice bran and wheat bran. JNutr, 120(4) 325-30. 

Cellulose, oat, and wheat fiber, which are all insoluble, have been incorporated with whey protein into an extruded product (Walsh and Wood, 2010). Increasing the fiber content led to decreases in air cell size. 

Onwulata, C. I., Konstance, R. P., Strange, E. D., Smith, P. W., and Holsinger, V. H. (2000). High-fiber snacks extruded from triticale and wheat formulations. Gereal Foods World 45, 470-473. 

Reddy BS, Mori H and Nicolais M. 1981. Effect of dietary wheat bran and dehydrated citrus fiber on azoxymethane-induced intestinal carcinogenesis in Fischer 344 rats. J Natl Cancer Inst 66 553-557. 

Amaranth T. versicolor ATCC 20869 Wheat straw, jute, hemp, maple woodchips, nylon, polyethylene teraphthalate fibers [44]... 

Wheat straw, jute, hemp, maple woodchips, and nylon and polyethylene ter-aphthalate fibers were tested for surface immobilization and decolorization of Amaranth by T. versicolor ATCC 20869 [44], They found that fungus immobilized on jute, straw, and hemp decolorized amaranth without glucose being added. Decolorization efficiency increased when 1 g/L glucose was added. 

In agricultural applications, the most commonly analyzed constituents are water, protein, starch, sugars, and fiber [16-20]. Such physical or chemical functions such as hardness of wheat, minerals, and food values have no actual relation to chemicals seen in the NIR. These are usually done by inferential spectroscopy. That is, the effect of minerals or the relationship of the spectra to in vitro reactions is used in lieu of chemical analyses to NIR active constituents. Considering that all shipments of grain from the US since the 1980s have been cleared by NIR, it can be argued that this is a critical application of the technique. 

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. 

The diet treatments were level of phytate intake, either 0.2 or 2.0 g/day. Each level was consumed for 15 days, three consecutive repeats of the 5-day menu cycle. To provide 2.0 g/day of phytic acid, 36 g of wheat bran was baked into 6 muffins and two muffins were eaten each meal. Dephytinized bran was prepared by incubating the bran in water and allowing the endogenous phytase to hydrolyze the phytate, then the entire incubation mixture was freeze-dried (4) and 36 g baked into 6 muffins. Thus, the intake of all nutrients and neutral detergent fiber was the same for both phytate intakes. Five subjects consumed the whole bran muffins for 15 days followed by the dephytinized bran muffins for 15 days and the other 5 subjects in the reverse order. Brilliant blue dye was given at breakfast on the first day of each collection period to aid in demarcation of stools. Stool composites were made for days 1-5, 6-15, 16-20 and 21-30 and urine composites for days 6-15, and 21-30. Daily food composites were made, homogenized, freeze-dried and then analyzed to determine mineral nutrient intakes. 

Our studies do not resolve the question of phytate vs fiber for the effect of wheat bran on dietary calcium bioavailability. Phytate level clearly affected apparent absorption of calcium in HS-II in the presence of an amount of the water insoluble fraction of dephytinized bran equivalent to 12 g of untreated bran and the phytate supplied as sodium phytate. An additional trial using untreated bran and the same amount of fiber as the water insoluble fraction with sodium phytate could resolve the question of fiber vs phytate. In HS-I, the balances were positive when a relatively large amount of bran, 36 g/day, was consumed. Calcium intakes were possibly higher than most men consume, but under the dietary conditions imposed for 15 days, the phytate and fiber of 36 g of bran did not express an adverse effect on calcium balance. 

More than 40 years ago, calcium absorption from brown (whole wheat) bread which was fed to human subjects was found to be poorer than was that when white (extracted wheat flour) was fed 04,5). Since then, many studies have sought to define the extent of inhibition of calcium intestinal bioavailability by various forms of dietary fiber with mixed results and conclusions (6-18). 

Serum calcium levels were depressed with the feeding of 18 to 100 g of wheat bran to human subjects in the study by Heaton and Pomare (10) but were unaffected by the feeding of approximately 20 g of wheat fiber in the study by Jenkins et al. (19). Since blood serum calcium levels tend to be resistant to change except under conditions of severe calcium deficiency, measurement of blood serum calcium levels is probably not sufficiently sensitive to indicate change in calcium nutritional status in short-term feeding studies. 

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... 

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). 

Water-holding capacity of hemicelluloses (contained in wheat brans and psyllium fiber) and celluloses may decrease mouth to rectum transit time, increase fecal weight, and decrease intraluminal pressure (36). These characteristics might be expected to interfere with calcium absorption decreasing time allowed for intestinal absorption, by diluting the concentration of calcium and... 

Diet Codes rwb = red wheat bran wwb = white wheat bran cb = corn bran rb = rice bran pf = psyllium fiber p = pectin c cellulose... 

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