Wheat Bran Dietary Fiber Research Articles

Small and large strain rheology of gluten and gluten-starch doughs containing wheat bran dietary fiber.

The small and large strain rheology of gluten (G) and gluten-starch (G + S) doughs containing wheat bran dietary fiber (WBDF) were investigated. At the small strain stage, i.e. frequency and strain sweep tests, the doughs containing high WBDF concentration are more vulnerable and unstable, as indicated by the lower dough linear viscoelastic strain limit as well as the higher slope of elastic modulus. However, the elastic nature of doughs remarkably increased upon WBDF addition, indicating the reinforcement of the dough mechanical strength, which is also confirmed by the large strain test wherein the maximum strain significantly decreased from 4.37 to 1.82 for the G system and from 12.09 to 2.72 for the G + S system. The creep recovery test showed that WBDF induced the reduction in the strain of the doughs at a fixed stress, which may be related to the enhanced strain hardening capacity. The addition of WBDF resulted in more brittle and unstable doughs with undesirable higher mechanical strength. The presence of starch greatly weakened the dough strength and led to inferior resistance to both small and large deformations. These findings confirmed the impairment of dough viscoelasticity upon addition of WBDF. © 2019 Society of Chemical Industry.

Study on the effect of wheat bran dietary fiber on the rheological properties of dough

Abstract The aim of the study was to determine the influence of wheat bran dietary fiber on wheat flour dough rheological properties. In this purpose, wheat bran dietary fiber (WBDF) with different levels (0, 3%, 6%, 9%, 12%) were added to wheat flour and the characterization of dough rheological properties was conducted by rapid visco-analyzer, farinograph, as well as rotational rheometer. The results from pasting properties showed a gradual reduction in peak viscosity, trough viscosity, final viscosity and setback with increasing WBDF content. At high WBDF concentration, the significant increase of water absorption, formation time as well as weakening degree implied the harder formation of gluten network structure and the competition for water between gluten and WBDF particles. Such conclusion was in line with the findings from dynamic rheology tests, in which the doughs containing WBDF were more sensitive to strain regardless of their rigid and stiff texture. This study revealed vulnerable dough structure induced by WBDF, as well as the strengthened elastic property, elaborating the harmful effects of WBDF on the rheological properties of doughs.

Gluten aggregation behavior in gluten and gluten-starch doughs after wheat bran dietary fiber addition

The influences of wheat bran dietary fiber (WBDF) on the structural changes and aggregation behavior of gluten in both gluten (G) and gluten-starch (G + S) systems were investigated. Six WBDF levels were provided in the G and G + S system to reveal the correlations between WBDF level and gluten depolymerization behavior. Results showed that WBDF caused a significant reduction in SS content and impaired water holding capacity, implying possible disaggregation behavior and less compact gluten network structure. The size exclusion chromatography profile also exhibited the loss of high molecular weight gluten aggregates in both G and G + S system. The Fourier transform-infrared spectroscopy results reveled an increase in β-sheet (∼55%) conformation at the cost of the β-turn structure, whereas random coils and aggregates tended to decrease. It may be speculated that the transformation of β-turn into β-sheet structure be responsible for the disaggregation behavior of gluten aggregates and the more rigid gluten network.

The thermal stability, structural changeability, and aggregability of glutenin and gliadin proteins induced by wheat bran dietary fiber.

Wheat bran dietary fiber (WBDF) has been reported to be responsible for the low quality of whole wheat flour products due to its destructive effect on the gluten matrix. Glutenin and gliadin are the major components of gluten protein and contribute to a proper gluten structure. In this study, the thermostability, surface hydrophobicity, fluorescence characteristics, free sulfhydryl contents, and molecular weight distributions of glutenin- and gliadin-rich fractions were determined after the addition of WBDF. The addition of WBDF to glutenin resulted in an increased surface hydrophobicity and free sulfhydryl content, as well as a red-shift of the fluorescence spectrum. However, the WBDF-modified gliadin fraction changed slightly mainly due to its spherical conformation. Size exclusion chromatography profiles revealed increasing soluble gliadin aggregates and decreasing high molecular weight glutenin fractions as a result of WBDF incorporation. The results from the thermostability analyses exhibited decreased weight loss and decomposition temperatures for both glutenin and gliadin proteins at high WBDF concentration. Our results suggest that changes in the gluten matrix caused by WBDF may largely rely on glutenin structure variation.

Impact of wheat bran dietary fiber on gluten and gluten-starch microstructure formation in dough

Visualization of the gluten network microstructure of dough is crucial to gain knowledge about the interactions of its various ingredients. In this study, various techniques, including mainly microscopy imaging, were applied to examine the effect of wheat bran dietary fiber (WBDF) on gluten (G) and gluten-starch (G+S) microstructure. The results revealed that doughs containing WBDF particles have a looser gluten structure and a larger number of large gas cells. This should be attributed to the thinning and breakage of protein fibrils caused by the WBDF, which lead to premature rupture of gas cells. In addition, light microscopy micrographs clearly showed that the WBDF particles settled around the gas cells and created a physical barrier, which might impose restrictions on gas cell expansion during proofing. These findings indicated impairment of the dough structure upon addition of the WBDF, implying the possible deterioration of the quality of wheat bran-fortified products.

Rheological properties of gluten and gluten‐starch model doughs containing wheat bran dietary fibre

SummaryThe effect of wheat bran dietary fibre (WBDF) on the texture and extensional properties of gluten (G) as well as gluten‐starch (G+S) doughs were investigated. Texture analysis revealed an increasing hardness of WBDF‐enriched doughs, ascribed to the gradual formation of intermolecular hydrogen bonds and weakened aggregation behaviour of gluten proteins. Extension results showed that G and G+S systems exhibited growing extension resistance thanks to the strengthened strain‐hardening capacity induced by WBDF. On the other hand, the WBDF accelerated the rupture of the gluten network and led to a downtrend of dough extensibility by increasing the friction with gluten branches and impairing the uniformity of the network structure. The findings indicate the possible impairment of the dough texture properties upon the addition of WBDF. Accordingly, for bran‐enriched flour products, the pretreatment with bran‐like particles leading to size reduction, softening or solubility improvement may be advantageous.

Influence of Wheat Starch on the Structural Changes and Size Distribution of Gluten Induced by Adding Wheat Bran Dietary Fiber

This study investigates the particle size distribution and structural changes in the gluten system with and without starch induced by adding wheat bran dietary fiber (WBDF). The results show that adding WBDF tends to disturb the particle size distribution of gluten considerably and causes changes in the hydrophobic group microenvironment. The presence of starch can reduce the destructive effects of gluten by forming a more open but solid gluten matrix, which led to larger‐sized particles. Moreover, the gluten‐starch system exhibited a significantly higher surface hydrophobicity value of 3694.4 but a lower fluorescence intensity possibly due to the quenching effect. Both systems had similar zeta potentials ranging from 17.4 to 18.4 mV, suggesting little impact of WBDF and starch on gluten electrostatic interactions. There results indicate that the changes in the gluten protein are determined not only by the amount of WBDF but also by the cooperation of starch.

Wheat Bran Dietary Fiber: Promising Source of Prebiotics with Antioxidant Potential

The potential of wheat bran (WB) addition as a prebiotic source were demonstrated using yogurt with probiotics (Lactobacillus acidophilus and Bifidobacterium lactis). Yogurts (with 4% WB) were significantly (P < 0.05) different in total bacterial counts (9.1 log CFU/mL), and total titratable acidity % (TTA, 1.4%) compared to controls during 28 days cold storage (4°C). Additionally, WB-total dietary fiber contents and their bound phenolic profiles were investigated as well as the antioxidant activity of WB-water extractable polysaccharides (WEP) was studied. HPLC analysis of alkaline hydrolyzed DF fractions showed that insoluble DF had higher phenolic acids (84.2%) content than soluble DF (15.8%). Also, crude-WEP showed stronger antioxidant activity compared to purified-WEP with an ORAC of 71.88 and 52.48 µmol TE/g, respectively. Here we demonstrate WB has potentials as a source of prebiotics, which may have the potentials for functional foods and nutraceutical applications.

Effects of cereal fiber on bowel function: A systematic review of intervention trials.

To comprehensively review and quantitatively summarize results from intervention studies that examined the effects of intact cereal dietary fiber on parameters of bowel function. A systematic literature search was conducted using PubMed and EMBASE. Supplementary literature searches included screening reference lists from relevant studies and reviews. Eligible outcomes were stool wet and dry weight, percentage water in stools, stool frequency and consistency, and total transit time. Weighted regression analyses generated mean change (± SD) in these measures per g/d of dietary fiber. Sixty-five intervention studies among generally healthy populations were identified. A quantitative examination of the effects of non-wheat sources of intact cereal dietary fibers was not possible due to an insufficient number of studies. Weighted regression analyses demonstrated that each extra g/d of wheat fiber increased total stool weight by 3.7 ± 0.09 g/d (P < 0.0001; 95%CI: 3.50-3.84), dry stool weight by 0.75 ± 0.03 g/d (P < 0.0001; 95%CI: 0.69-0.82), and stool frequency by 0.004 ± 0.002 times/d (P = 0.0346; 95%CI: 0.0003-0.0078). Transit time decreased by 0.78 ± 0.13 h per additional g/d (P < 0.0001; 95%CI: 0.53-1.04) of wheat fiber among those with an initial transit time greater than 48 h. Wheat dietary fiber, and predominately wheat bran dietary fiber, improves measures of bowel function.

Semisolid meal enriched in oat bran decreases plasma glucose and insulin levels, but does not change gastrointestinal peptide responses or short-term appetite in healthy subjects

Background and aims Dietary fibre (DF) may play an important role in weight control. The amount, type and way of processing of DF modify food structure and subsequent postprandial appetitive, metabolic and hormonal effects, but current understanding about the magnitude of effects that specific types and amounts of DF exert are still poorly understood. Methods and results We investigated the effects of wheat and oat brans alone and as combination in semisolid food matrix on postprandial appetite profile and gastrointestinal (GI) hormonal responses. Twenty healthy, normal-weight subjects (5 male/15 female, aged 23.3 ± 0.85 y) participated in the study. Isoenergetic and isovolumic (1250 kJ, 300 g) puddings with different insoluble and soluble DF content were tested in a randomised order: pudding with 1) no added fibre, 2) 10 g wheat bran DF, 3) 10 g oat bran DF and 4) combination including 5 g wheat bran DF + 5 g oat bran DF. Blood samples were drawn before and 15, 30, 45, 60, 90, 120 and 180 min after the test meals to determine plasma glucose, ghrelin, peptide YY (PYY) and serum insulin concentrations. Subjective profiles of appetite were assessed using visual analogue scales (VAS). Plasma glucose ( P = 0.001) and serum insulin ( P < 0.001) responses were the lowest after the pudding with the greatest amount of β-glucan. In contrast, postprandial ghrelin or PYY responses or appetite sensations did not differ among the meals. Conclusion Oat β-glucan decreased postprandial plasma glucose and serum insulin responses, yet had no significant effects on GI peptide responses or appetite ratings.

In vitro fermentation of xylooligosaccharides from wheat bran insoluble dietary fiber by Bifidobacteria

The utilization of xylooligosaccharides (XOS) from wheat bran dietary fiber by four Bifidobacterium strains ( Bifidobacterium adolescentis, Bifidobacterium longum, Bifidobacterium bifidum and Bifidobacterium breve) was investigated. Among the tested strains, B. adolescentis displayed the highest growth on XOS, whereas B. breve showed no growth. Further, the in vitro kinetic analysis of fermentation of XOS by B. adolescentis was performed. The maximum value of biomass yield and the lowest pH value of the culture broth were arrived at 7.22 mg/mL and 5.1, respectively, after in vitro fermentation for 24 h. The consumption of XOS by B. adolescentis reached 70.4% after 24 h, which preferred XOS with a degree of polymerization (DP) of 3 with 88% of percentage consumption, followed by DP 2, and DP 4–7. The total production of short-chain fatty acids, predominately acetate, reached 7.47 mg/mL in the fermentation of XOS.

Effect of ultrafine grinding on hydration and antioxidant properties of wheat bran dietary fiber

Abstract Wheat bran dietary fiber (DF) powders was prepared by ultrafine grinding, whose effects were investigated on the composition, hydration and antioxidant properties of the wheat bran DF products. The results showed that ultrafine grinding could effectively pulverize the fiber particles to submicron scale. As particle size decrease, the hydration properties (water holding capacity, water retention capacity and swelling capacity) of wheat bran DF were significantly (p

Dietary fibre: its composition and role in protection against colorectal cancer

Dietary fibre has a complex and highly variable composition. Although some dietary fibres may protect against colorectal cancer, it is unlikely that all are equally protective. Dietary fibre is principally composed of plant cell walls, but it also includes components obtained from cell walls (e.g. cellulose, pectin, and lignin), and non-starch polysaccharides (NSPs) from other sources (e.g. seaweeds and micro-organisms). The AOAC and Englyst methods are commonly used to determine the total amount of dietary fibre in foods. Most of the cell walls in food plants are from parenchyma cells, which are extensively degraded by bacteria in the colon. Cell types with walls containing the hydrophibic polymers lignin, suberin, or cutin also occur in food plants in small numbers, but they may be important in preventing colorectal cancer. Lignin, and possibly the other polymers, protect these walls from degradation. Epidemiological, human intervention, and animal studies can be used to try to identify the most protective dietary fibres. Epidemiological studies are difficult to interpret because usually only the total amount of dietary fibre eaten is reported. Intervention studies indicate that wheat bran dietary fibre may be protective. The results of animal carcinogenesis studies are variable, but sources of insoluble dietary fibres, including wheat bran, appear more protective than soluble dietary fibres, and some dietary fibres appear to enhance carcinogenesis. Possible mechanisms for protection by dietary fibres can be divided into two groups: those where the dietary fibre is acting directly, and those which result from the dietary fibre being degraded by colonic bacterial enzymes and the products fermented. Possible direct mechanisms include the binding of carcinogens to undegradable dietary fibres, and the absortion of water by undegradable dietary fibre resulting in increased faecal bulk and shortened transit times. Possible indirect mechanisms include the lowering of the colon pH by the short-chain fatty acids produced by bacterial fermentation, and the specific effects of butyrate. There are also a number of possible mechanisms by which some dietary fibres may enhance carcinogenesis. Use of better defined dietary fibres will increase our understanding of the role of dietary fibres in modulating colorectal cancer.