Coarse Bran Research Articles

Nutritive value of coarse and fine wheat brans for rabbits

The objective of this study was to compare the nutritive value of two wheat brans obtained at different stages of milling, described commercially as coarse and fine wheat bran. Digestibility trials of four samples of coarse and four of fine wheat bran from four commercial Spanish firms were carried out in 90 New Zealand White×Californian rabbits fed ad libitum. Fine brans were characterised by a higher content of particles of less than 1 mm, while coarse brans had a higher content of particles greater than 2 mm. There was no significant differences in the chemical composition of the brans, but fine brans showed, on average, a significantly higher ( P<0.05) content of crude protein bound to acid-detergent fibre (2.94 vs. 1.90 g CP–ADF kg −1 dry matter). The digestibility of the chemical components did not vary widely except for crude fibre and crude protein (CP) which were, on average, significantly higher in coarse than fine bran. Animals on coarse bran consumed more feed (126.2 g/day) than those on fine bran (111.7 g/day). The best single predictor of digestible energy (DE) and gross energy digestibility (dGE) was ADF ( R 2 /R max 2 =0.81 and 0.79 , respectively; P<0.001). A significant improvement in the accuracy of prediction was obtained when CP–ADF ( P<0.01) was introduced into the model ( R 2 /R max 2=0.88 and 0.89 for DE and dGE, respectively). The best prediction for crude protein digestibility (dCP) was obtained by the inclusion in the model of both ADF and CP–ADF ( R 2/ R max 2=0.64; P<0.001). For digestible protein, the best single predictor was acid-detergent lignin ( R 2/ R max 2=0.63; P<0.001), although accuracy of digestible protein prediction was improved with crude protein and CP–ADF as independent variables ( R 2/ R max 2=0.69; P<0.001). Results suggest that the classification of wheat bran into coarse and fine brans is difficult to justify from their chemical composition and that their nutritive value seem to be related to the digestibility of its fibrous or protein fractions and less to other nutritive components.

INSTRUMENTAL TEXTURE and BAKING QUALITY of HIGH-FIBER TOAST BREAD AS AFFECTED BY ADDED WHEAT MILL FRACTIONS

The effect of bran type, level of addition, particle size, addition of wheat germ, as well as other additives like improvers and dough conditioners, on the instrumental texture and baking quality of high-fiber toast bread (white pan bread) has been investigated. the specific loaf volume decreased significantly (3.45 cc/g) when the bran level was raised to 30%, but at 20% bran addition, the specific loaf volume was superior to that of the control bread. the specific loaf volume of test breads remained higher than the control bread up to a level of 7.5% wheat germ addition. Additives like ascorbic acid (50 ppm) and sodium stearoyl-2-lactylate (0.5%) further improved the baking quality of test bread samples. the objective texture values (measured as compression force, kg) indicated that the test bread with bran addition up to 20% and germ up to 7.5% possessed a softer texture (0.80 kg) than the control bread (1.02 kg). In comparison with control bread, the panelists gave higher sensory scores for all attributes of test bread samples containing up to 20% red coarse bran or up to 30% red fine bran. A similar trend in sensory quality of test samples containing up to 7.5% wheat germ was also observed. High-fiber toast bread made from white flour, equal proportions of coarse and fine bran at 20%, wheat germ at 7.5%, plus sodium stearoyl-2-lactylate at 0.5% levels, was found to possess softer texture and improved sensory quality than the whole wheat flour bread.

Wheat bran particle size effects on bread baking performance and quality

Commercial hard red spring, hard red winter, soft white and durum wheat brans were used to evaluate the particle size effect of wheat bran on bread baking performance and bread sensory quality. Three different particle size bran samples were obtained from each bran by grinding, not by sifting, the bran samples. The bran samples were similar in chemical composition, but different in particle sizes. Results of baking experiments showed that breads containing fine bran had lower specific loaf volume and darker crumb colour than breads containing coarse or medium size bran. Sensory test panellists found that fine bran contributed smoother crust appearance and less gritty mouthfeel than the coarse bran. The sensory panel also indicated that breads containing soft white wheat bran had significantly better flavour and mouthfeel than breads containing hard red spring wheat bran.

Wheat bran particle size effects on bread baking performance and quality

Commercial hard red spring, hard red winter, soft white and durum wheat brans were used to evaluate the particle size effect of wheat bran on bread baking performance and bread sensory quality. Three different particle size bran samples were obtained from each bran by grinding, not by sifting, the bran samples. The bran samples were similar in chemical composition, but different in particle sizes. Results of baking experiments showed that breads containing fine bran had lower specific loaf volume and darker crumb colour than breads containing coarse or medium size bran. Sensory test panellists found that fine bran contributed smoother crust appearance and less gritty mouthfeel than the coarse bran. The sensory panel also indicated that breads containing soft white wheat bran had significantly better flavour and mouthfeel than breads containing hard red spring wheat bran. © 1999 Society of Chemical Industry

Effect of Wheat Bran on Serum Lipids: Influence of Particle Size and Wheat Protein

Objective: Wheat fiber appears to protect from cardiovascular disease despite its lack of consistent effect on serum lipids. We therefore wished to determine whether reported inconsistencies in the effect of wheat bran resulted from differences in particle size or its high gluten content.Methods: Two studies were conducted. In one-month metabolic diets, 24 hyperlipidemic subjects consumed breads providing an additional 19 g/d dietary fiber as medium or ultra-fine wheat bran and extra protein (10% of energy as wheat gluten). In two-week ad libitum diets, 24 predominantly normolipidemic subjects consumed breakfast cereals providing an additional 19 g/d of dietary fiber as coarse or a mixture of ultra-fine and coarse wheat bran with no change in gluten intake. Both studies followed a randomized crossover design with control periods when subjects ate low-fiber breads and cereals respectively with no added gluten. Fasting blood lipids were measured on day zero and at the end of each phase.Results: Wheat bran had no effect on total, LDL or HDL cholesterol irrespective of particle size or level of gluten in the diet. However, consumption of increased gluten in the metabolic study was associated with a 13±4% reduction in serum triglycerides (p=0.005) which was not seen in the normal-gluten ad libitum study.Conclusions: The protective effect of wheat fiber in cardiovascular disease cannot be explained by an effect of wheat bran in reducing serum cholesterol although in hyperlipidemic subjects displacement of carbohydrate by gluten on the high-fiber phases was associated with lower serum triglycerides.

Effect of Wheat Bran Particle Size on Dough Rheological Properties

Commercial hard red spring, hard red winter, soft white and durum wheat brans were used to investigate the effect of wheat bran particle size on the rheological properties of doughs. Wheat brans were first coarsely ground and passed through a bran finisher to remove additional endosperm and aleurone layers. These processes increased total dietary fibre content and decreased starch content of the wheat bran samples. Three particle size distributions, for each wheat bran class, were obtained by further grinding (not by sifting) of the bran samples by different experimental mills. Coarse bran can retain significantly more water than medium or fine bran as measured by a centrifuge method, but bran particle size had no significant effect on dough water absorption. Addition of wheat bran into bread dough systems increased dough water absorption rate, reduced mixing time and decreased dough mixing tolerance as measured by farinograph. Fine particle size wheat bran decreased dough mixing tolerance and reduced mixing time compared to coarse bran. Dough containing fine particle size bran exhibited more strength than dough containing coarse bran after a 180-min rest period as measured by the extensigraph. © 1997 SCI.

Unexpected Strengthening Effects of a Coarse Wheat Bran on Dough Rheological Properties and Baking Quality

Grain from the wheat varieties Bezostaya and Gerek were milled in a Bühler laboratory mill to obtain straight-run flour, fine bran and coarse bran. When the fine brans from both wheats were added to the respective parent flours at levels of 5%, 10% and 15% a weakening effect was noted in farinograms and extensograms, and loaf volumes were reduced. The coarse bran from Bezostaya wheat added to Bezostaya flour showed similar effects. However, coarse bran from Gerek wheat added to either flour, showed unexpected strengthening effects and had a lessened deleterious effect on loaf volume.

Effect of bran particle size on gastric emptying and small bowel transit in humans: a scintigraphic study.

Bran is an effective treatment for constipation but its use is often limited by heartburn and bloating. This study examined the effect of fine and coarse bran (15 g) on the gastric emptying and small bowel transit of a 325 kcal rice test meal. Twelve healthy volunteers underwent a three way cross over study, ingesting the technetium-99m labelled rice meal with or without 15 g of indium-111m labelled fine or coarse bran, in random order. Serial scintigraphic images were obtained to define gastric emptying and colonic arrival of label. Compared with control values (99 (9) minutes) (mean (SEM)), the time to 50% gastric emptying was significantly delayed by coarse but not fine bran, being 121 (6) and 104 (9) minutes respectively, p < 0.05, n = 12. Fundal emptying was unchanged but both brans seemed to increase the proportion of isotope in the antrum at 90 minutes. Small bowel transit was slightly faster with both bran types but in this study the difference was not significant. Both the bran and rice labels moved down the gut without significant separation. Fine bran causes less disturbance of gastric physiology than coarse bran.

Estimation of fat acidity in milled wheat products. Part II. Using colorimetry to ascertain the effect of storage time and conditions

Milled wheat products were stored for 12 weeks at 20, 30 and 37°C in commercial packaging and analysed throughout the trial for fat acidity by copper soap colorimetry. Accumulation of fatty acid was highest in pollard and decreased in the order: coarse bran, meal containing coarse bran and pollard, meal containing coarse bran only, and flour. Increased storage temperature resulted in a higher rate of fatty acid release and moisture loss. Rate of development of fat acidity lessened as sample moisture decreased. Moisture loss during the trial was marked for samples packaged in hessian and paper sacks. Packaging in polythene greatly reduced moisture loss. No synergistic effect was observed between fractions in the meals during storage.

Effect of Flour Milling Conditions on the Quality of Indian Unleavened Flat Bread (Chapati)

ABSTRACTThe effect of whole wheat flour granulation, bran size, damaged starch and protein contents on the quality of chapati is reported. The cutting, puncture and stretching force values (taken on Zwick universal testing machine) on chapaties produced from finer whole wheat flour with higher damaged starch as well as higher water absorption, were lower, thus indicating their soft texture. The inclusion of coarse bran (15%) into 85% extraction flour, adversely affected the chapati texture; however a similar addition of fine bran showed no deterimental effect.

The effects of aqueous extraction on the performance of wheat bran in bread

AbstractWheat bran was sieved into coarse, medium and fine fractions prior to extraction with tap water. Bran, bran extract and bran residue were analysed for moisture, protein, fat, ash, pentosan and phytic acid. Farinograph measurements and baking tests showed maximum dough resistance and loaf volume of a white flour were both increased by the addition of the residue. Both these parameters were substantially decreased by bran extract and, to a lesser degree, by the bran itself. These findings were common amongst the size fractions although the residue from the coarse bran had the greatest effect on loaf volume and dough properties.

Dietary Fiber and Fecal Characteristics in Rats: Effects of Level and Particle Size of Bran

Particle size and levels of dietary wheat brans were compared in regard to their effects on various fecal characteristics in rats. Particle size appeared to have no effect on fecal moisture. When compared with a 15% medium bran diet, a 15% fine bran diet decreased wet weight (−9%, P &lt; 0.01) and volume (−18%, P &lt; 0.01), and increased density (+14%, P &lt; 0.01) of feces. A 15% coarse bran diet induced a low fecal density (0.839), which is a desirable effect. Density decreased when the level of bran of the same particle size was increased. However, a 25% fine bran diet still induced higher (P &lt; 0.05) density than a 15% coarse bran diet, stressing the importance of bran coarseness on fecal density.

The Influence of Dietary Fiber Source on Human Intestinal Transit and Stool Output

Wheat bran ground to a coarse and fine particle size, purified cellulose and ethanol-extracted cabbage fiber, fed to 24 adult males during an 80-day metabolic trial, were examined for eeffects on intestinal transit time, laxation and stool composition. Brilliant blue, plastic pellets, polyethylene glycol (PEG)-4000 and Cr(III) mordanted onto isolated bran fiber were simultaneously administered for transit measurements. Intersubject variability in response to fiber source was highly significant for all transit and stool measurements. Only coarse bran or cellulose addition increased transit speed (decreased transit time) over basal rates. Grinding of bran significantly reduced fecal output because of reduced fecal water. Only subjects consuming cellulose or fine bran reported difficult or uncomfortable defecations. Though cabbage produced the smallest fecal output, stools had a high moisture content comparable to those obtained from coarse bran, which suggests a large microbial output in response to a fermentable substrate. Significant negative correlations were produced when changes in dry matter or cell wall intakes were regressed with Cr (III) transit. These findings suggest that the level of either food or fiber in the diet are variables that influence intestinal transit time and should be controlled in studies measuring it. Increases in fiber intake linearly increased fecal output of water and dry matter. Regression slopes were characteristic of each fiber source.

Influence of Dietary Fibers on Fermentation in the Human Large Intestine

Fiber sources were fed to 24 men to evaluate the effect of fiber on large intestinal microflora. The diets were a low fiber basal or the basal diet supplemented with coarse bran, fine bran, cabbage, or cellulose (Solka floc). Twelve subjects (Group 1) were fed all fiber sources using a latin square design with 2-week experimental periods followed by a 3-week period on the basal diet. Group 2 made one diet change after the first experimental period, then remained on that diet throughout the experiment; during the last period their fiber intake was doubled (to approximately 26 g/day). A microbial culture system was utilized with fecal microflora to measure cell wall indigestibility and volatile fatty acid (VFA) production. Volatile fatty acids were also measured in fresh feces. The in vitro substrates were alfalfa, coarse bran, cabbage, or cellulose. In this system, dietary fiber had a significant (P < .05) effect on resultant cell wall indigestibility and VFA levels. Previous diet in group 1 subjects significantly (P < .05) affected in vitro VFA. In group 2 significant (P < .05) period and subject effects were present for the in vitro VFA data. The VFA concentrations in feces of humans were significantly affected by the fiber consumed.dietary fiber fermentation large intestine human

The Effect of Certain Dietary Factors on in vivo pH Changes and Pepsin Activity in the Stomach of the Growing Pig

SUMMARY In change-over type experiments the effects of cereal base of the diet and feeding method on in vivo pH changes and pepsin activity in the stomach of the growing pig were studied. In vivo pH levels and pepsin activity were inversely related. Barley-based diets and wet methods of feeding gave, overall, lower pH levels than maize-based diets and dry methods of feeding. Increasing the fibre level of maize-based diets, by adding coarse bran, lowered the pH level. It is suggested that such changes in gastric acidity and pepsin activity may be important in the aetiology of gastric ulceration and in modifying the activity of certain bacteria in the gut.

Some British Work on Nutrition

NUTRITION is the theme of vol. 2, Nos. 10 and 11 of the British Medical Bulletin, The issue opens with an article on nutritional science in medicine by Sir Edward Mellanby. Sir Edward pleads for an international agreement on the optimum composition of bread and other cereal foods which form such a large proportion of the normal diet. The Health Section of the League of Nations has prepared the way for this kind of agreement by working out the international standardization of vitamins and by setting up standards of nutrition in terms of common foods. Discussing bread, Sir Edward says that British men of science consider that it should be made of flour containing as much of the wheat grain as can be physiologically absorbed, that is to say, the whole grain except the outer coarse bran; some North American workers, on the other hand, favour the old type of low-extraction, and white flour with the addition of vitamins known to be present in the wheat grain. The health of the consumer, said Sir Edward, and not the milling or other interests concerned, should control the composition of bread.

Digestibility trials with poultry. X. The effect of war-time changes in milling practice on the composition and nutritive value of fine and coarse wheat bran

Digestibility tests with poultry, and one with rabbits, on brans produced under war-time conditions led to the following conclusions:1. Changes in war-time milling practice, brought about by the implementation of Government policy directed towards maximum production of flour for human use, at first led to the production of a fine bran, somewhat better in food value than prewar bran, and a coarse bran, of poorer quality than pre-war bran. Later, owing to dilution of the grist with barley, the quality of the fine bran deteriorated and became worse than that of prewar bran.2. The changes noted were largely caused by the extremely efficient removal of the starch by the millers, and reflect the ability shown by the milling industry in diverting to human food supplies the maximum possible edible food material present in the wheat berry.3. The superior efficiency of the rabbit's digestive system for dealing with fibrous foods, as compared with the fowl's, is emphasized by the differences in the amounts of digestible nutrients extracted from a given sample of coarse bran by these two classes of animals. 1 kg. of coarse bran yielded 2522 kg. cal. of metabolizable energy in the rabbit as compared with 1637 kg. cal. in the fowl.

The influence of war-time milling control on the composition, digestibility and nutritive value of the wheaten offals

The investigations described in this paper are concerned with the influence of the various war-time changes in milling practice on the composition, digestibility and nutritive value, both for ruminants, and pigs, of the wheaten milling offals. The need for obtaining a larger output of flour for human consumption led to the raising of the rate of flour extraction from 70 to 75 % at an early stage of the war, and this was increased further to 85% with the introduction of the ‘national wheat-meal loaf’ in 1942. Two grades of wheaten offals only were marketed at this stage of the war—fine bran and coarse bran. Early in 1943 it became permissible to incorporate a proportion of rye, barley or de-husked oats in the wheat before milling. It was considered unlikely that the inclusion of rye or de-husked oats would exert any adverse influence on the nutritive value of the milling offals. When barley is used to dilute the wheat, however, the husk from this grain finds its way into the offals, and it was therefore to be anticipated that the presence of the barley husk would cause the fibre content of the offals to be raised and their nutritive value to be lowered. Authority has been given for the use of a grist that will give rise to a flour containing up to 10% of barley flour, but at the time of writing it would appear that, in actual practice, flour millers have not exceeded 10% of barley in the grist itself.