Physicochemical Properties Of Wheat Bran Research Articles

Solid‐state fermentation by Aspergillus niger and Lactobacillus plantarum improved the nutritional and physicochemical properties of wheat bran and whole wheat bread

SummarySolid‐state fermentation (SSF) is an economically viable processing technique to improve the bioactive content from agricultural by‐products. The impacts of SSF by Aspergillus niger (AN) and Lactobacillus plantarum (LP) on the physicochemical and functional properties of wheat bran and whole wheat bread were investigated in this study. Compared with unfermented wheat bran, the pH of fermented wheat bran decreased significantly, and the titrated acidity increased significantly. The water absorption index, water solubility index and swelling capacity of wheat bran were significantly increased after fermentation. Besides, the free‐radical scavenging activities for DPPH, ABTS and the total antioxidant capacity of wheat bran were notably increased after SSF. Moreover, the content of alkylresorcinols (ARs), total phenolics and flavonoids compounds in wheat bran were enhanced by 137.85%, 52.87% and 95.6%, respectively, after fermentation. The content of aflatoxin B1, deoxynivalenol, zearalenone and ochratoxin A were decreased by 76.34%, 18.67%, 34.48% and 20.46%, respectively. SSF enhanced the content of ARs, total phenols and flavonoids in the reconstituted whole wheat bread by 136.55%, 54.55% and 97.74%, respectively. Whereas, the hardness and chewiness of the bran‐rich bread were decreased by 75.2% and 92.41%, respectively. Additionally, the sensory evaluation score, specific volume and the overall score of reconstituted bread were significantly improved. Taken together, SSF by AN and LP could improve the processing value of wheat bran and might be a feasible solution to upgrade whole wheat product quality.

Solid-state fermentation by S. cerevisiae with high resistance to ferulic acid improves the physicochemical properties of wheat bran and quality of bran-rich Chinese steamed bread.

Wheat bran has numerous health benefits, but its poor processing and sensory properties limit its application in the staple food industry. Fermentation by S. cerevisiae changes the performance of wheat bran. However, high levels of ferulic acid (FA) inhibit S. cerevisiae. The effects of solid-state fermentation of S. cerevisiae with high resistance to FA on the physicochemical properties of wheat bran and the quality of bran-rich Chinese steamed bread (CSB) were investigated. The results showed that the growth of S. cerevisiae was inhibited by FA in a dose-dependent manner. Short-term adaptation strategies efficiently improved the tolerance of S. cerevisiae to FA stress. Compared with the parental strain (PS), fermentation of the short-term adapted strains (adapted strains) significantly increased the FA, total phenol, and soluble dietary fiber content in wheat bran. Wheat bran fermented by the adapted strains had a higher antioxidant capacity than wheat bran fermented by PS. In addition, compared with the PS, the wheat bran fermented by the adapted strains can decrease the hardness, improve the specific volume, and the quality of CSB. Thus, solid-state fermentation of the adapted strain is a potentially effective method to improve the nutritional and physicochemical properties of wheat bran as a cereal food ingredient.

Double-Edged Metabolic Effects from Short-Term Feeding of Functionalized Wheat Bran to Mouse Revealed by Metabolomic Profiling

Health-promoting activities of wheat bran are limited by the high-degree crosslinking of its dietary fiber and the low bioavailability of its phenolics. In this study, functionalized wheat bran (FWB) was prepared through a combination of milling, alkaline hydrolysis, high-shear mixing, and high-pressure homogenization treatments. Feasibility and metabolic effects of feeding FWB were investigated by a short-term mouse feeding trial and liquid chromatography-mass spectrometry-based metabolomic analysis. The combinatorial processing dramatically enhanced the function-associated physicochemical properties of wheat bran, including viscosity, fiber compositions, free ferulic acid, and antioxidant capacity. FWB feeding led to diverse positive metabolic effects, including fecal sequestration of bile acids and cholesterol, reduced serum triacylglycerols and cholesterol, elevated fermentation for short-chain fatty acids, increased bioavailability of ferulic acid and its microbial metabolites, and improved redox balance. However, FWB feeding also negatively affected the nutritional status by decreasing the bioavailability of essential amino acids through the excessive loss of amino acids in feces and disrupting lipid homeostasis by reducing choline supply in the liver. These double-edged metabolic effects warrant further investigations on how to achieve the balance between the functionalization of wheat bran bioactives and the disruption of nutrient bioavailability.

Metabolomics Profiling Revealed Double-Edged Metabolic Effects of Functionalized Wheat Bran in Mouse

Abstract Objectives Wheat bran is rich in bioactive components, mainly dietary fiber, micronutrients, and phytochemical contents. However, the health-promoting effects of wheat bran is restricted by the high-degree crosslinking of dietary fiber and low bioavailability of phytochemicals. The present study aims to improve the functions of wheat bran by increasing the levels of soluble fiber and free ferulic acid from optimized processing to examine the metabolic effects of consuming functionalized wheat bran (FWB) in mice. Methods Control wheat bran (CWB) was processed by an optimized combination of milling, high pressure pulverization, and alkali treatment, leading to dramatic increases of soluble fiber and free ferulic acid. Three groups of male mice were fed the control AIN93G diet, and two modified AIN93G diets containing 10% of CWB and 10% FWB, respectively, for 7 days. The effects of CWB and FWB on the mouse metabolome were determined through the LC-MS based metabolomics analysis of feces, liver, serum, and urine samples. Results The processing dramatically improved the function-associated physicochemical properties of wheat bran, including the increases of soluble fiber content and viscosity by milling and high-pressure pulverization and the elevation of free ferulic acid by alkali treatment. FWB feeding elevated microbial SCFAs production, promoted the excretion of bile acids and cholesterol in feces, modified the lipidome in the liver, decreased triacylglycerols and cholesterol in serum, and increased the levels of ferulic acid and microbial metabolites in urine. On the other hand, FWB feeding resulted in the increases of free amino acids in feces and the decreases of essential amino acids, choline and its metabolites in the liver. Conclusions The optimized processing dramatically increased the soluble fiber and free ferulic acid contents of wheat bran, resulting in improved hypocholesterolemic and antioxidant functions of FWB. However, the bioavailability of nutrients, including essential amino acids and choline, and the homeostasis of lipidome could be negatively affected by FWB diet. These double-edged metabolic effects warrant further investigations on how to achieve the balance between the functionalization of bioactive components and the disruption of nutrient bioavailability in wheat bran processing. Funding Sources NIFA project MIN-18–125.

The Effect of Wet Milling and Cryogenic Milling on the Structure and Physicochemical Properties of Wheat Bran.

Wheat bran consumption is associated with several health benefits, but its incorporation into food products remains low because of sensory and technofunctional issues. Besides, its full beneficial potential is probably not achieved because of its recalcitrant nature and inaccessible structure. Particle size reduction can affect both technofunctional and nutrition-related properties. Therefore, in this study, wet milling and cryogenic milling, two techniques that showed potential for extreme particle size reduction, were used. The effect of the milling techniques, performed on laboratory and large scale, was evaluated on the structure and physicochemical properties of wheat bran. With a median particle size (d50) of 6 µm, the smallest particle size was achieved with cryogenic milling on a laboratory scale. Cryogenic milling on a large scale and wet milling on laboratory and large scale resulted in a particle size reduction to a d50 of 28–38 µm. In the milled samples, the wheat bran structure was broken down, and almost all cells were opened. Wet milling on laboratory and large scale resulted in bran with a more porous structure, a larger surface area and a higher capacity for binding water compared to cryogenic milling on a large scale. The extensive particle size reduction by cryogenic milling on a laboratory scale resulted in wheat bran with the highest surface area and strong water retention capacity. Endogenous enzyme activity and mechanical breakdown during the different milling procedures resulted in different extents of breakdown of starch, sucrose, β-glucan, arabinoxylan and phytate. Therefore, the diverse impact of the milling techniques on the physicochemical properties of wheat bran could be used to target different technofunctional and health-related properties.

Study into the effect of microfluidisation processing parameters on the physicochemical properties of wheat (Triticum aestivum L.) bran

The physicochemical properties of wheat bran have an effect on its technofunctional and nutritional profile. The possibility to induce physicochemical modifications in wheat bran using microfluidisation was investigated. An I-optimal experimental design was used to investigate the effect of microfluidisation processing parameters (pressure, number of passes, bran concentration and initial particle size) on important properties of wheat bran (particle size, microstructure, chemical composition, water retention capacity (WRC), extractability, viscosity and sedimentation). With the parameters used in this study, microfluidisation reduced wheat bran median particle size to 14.8 μm and disintegrated starch granules from the attached endosperm. This coincided with an increased extractability of starch and arabinoxylan. While the initial particle size was of minor importance, a higher pressure, larger number of passes and lower bran concentration during microfluidisation resulted in a smaller particle size, higher WRC and extractability, and an increased viscosity and stability in a 2% wheat bran suspension.

Physicochemical characterization of wheat bran and Kappaphycus alvarezii dietary fibres and their ability to bind mutagens, PhIP, Trp-P-2, AαC and BαP

The physicochemical properties of wheat bran and Kappaphycus alvarezii, and their binding ability to heterocyclic amines and polycyclic aromatic hydrocarbons such as, PhIP, Trp-P-2, AαC and BαP, were investigated. High swelling capacity (14.9 mL/g) and water retention capacity (10.4 g/g) observed in K. alvarezii could be attributed to the high amounts of soluble fraction (68%). Galactose dominated in K. alvarezii dietary fibre, having alternating units of d-galactose-4-sulphate and 3,6-anhydro-d-galactose. Wheat bran consisted of glucose, xylose and arabinose, which formed cellulose and hemicelluloses. Presence of sulphur is another distinct property of K. alvarezii. Insoluble and soluble fractions of K. alvarezii dietary fibre showed superior binding ability than wheat bran. Hydrophobic mutagens were more effectively adsorbed to the dietary fibres. Molecular dynamics simulation indicated that the interaction energy between BαP and both the dietary fibres were lowest, possibly indicating a strong interaction between the planar rings of BαP and the fibre. The molecular dynamics results indicated high interaction energy for mutagens with marine fibre that were in accordance with the experimental results.

고압균질처리에 따른 산지별 밀기울의 이화학적 특성

본 연구에서는 영양적으로 우수한 밀기울의 식품 소재화를 위해 산지별 밀기울의 고압균질처리에 따른 이화학적 특성변화를 연구하였다. 고압균질처리로 밀기울의 입자 크기를 효과적으로 줄일 수 있었으며, 이러한 미세화 처리에 의해 물리 화학적 특성을 변화시킬 수 있었다. 입자 크기와 용적밀도가 감소함에 따라 보수력, 팽창력, 보유력 및 양이온치환력을 증가시킬 수 있었다(p<0.05). 이는 고압균질기의 노즐 지름이 작을수록, 통과횟수가 많을수록 증가하는 경향이 있었다. IC 200으로 1회 및 IC 100 2회 처리한 시료에 있어서는 유의적인 차이가 있었으나 IC 100 5회 처리한 시료는 IC 100 2회 처리한 시료와 유의적인 차이가 없었다. 따라서 경제적인 면과 기능적인 면을 고려할 때 IC 100 2회 처리한 시료가 가장 효율적임을 알 수 있었다. 또한 산지별 밀기울 간에는 이화학적 특성에 큰 차이가 없는 것으로 나타나 우리밀과 수입밀의 밀기울 특성에는 차이가 없음을 알 수 있었다. 결론적으로 밀기울의 고압균질처리에 의해 불용성 식이섬유소의 기능을 향상시킬 수 있으며 나아가 섬유소를 강화하고 유지와 수분의 보유를 필요로 하며 지질 흡수를 저해하는 식품에 기능성 소재로서 활용할 수 있을 것이다. 따라서 본 연구는 미세화 처리를 통한 기능성 식품소재 개발에 도움이 될 것으로 사료된다. In this study, the effects of high-pressure homogenizer treatment on the physicochemical properties of wheat bran from different areas were evaluated. The results showed that the high-pressure homogenizer process could effectively decrease particle size and loosen the microstructure of the wheat bran matrix. As the particle size decreased, the bulk density of wheat bran was significantly decreased (p<0.05) and the water-holding capacity, swelling capacity, oil-holding capacity, and cation-exchange capacity were substantially increased. In addition, microscopic analysis revealed the gradual disintegration of the original cell wall structure and the dissociation of bran tissues over the course of high-pressure homogenization treatment. Scanning electron micrographs showed that the process could also effectively separate out the structural components of wheat bran. These results suggest that the high-pressure homogenizer process is an effective method to modify the physicochemical properties of wheat bran and likely other cereal brans, which might provide potential fiber-rich ingredients for use in functional foods.

Effects of microfluidization on antioxidant properties of wheat bran

Phenolic compounds present in native wheat bran are majorly bound to polysaccharides and entrapped in the fibre matrix. Recently, it was demonstrated that the microfluidization process could significantly improve physicochemical properties of wheat bran due to particle size reduction and microstructure modification. The current study provides further evidence that the process also significantly increased the contents of surface-reactive, alkaline and acid hydrolysable phenolics by 280%, 60% and 20%, respectively, after a total of 8 passes through the IC200 and IC87 chambers. Accordingly, the associated antioxidant capacity increased with increase in the extent of the treatment. However, there was a decrease in solvent extractable phenolic contents due to their dispersion in water and loss during the treatment. It is also worth noting that the residues after alkaline and acid hydrolysis still contained a high content of surface-reactive phenolics, which might indicate a significant underestimation of the total phenolic content and antioxidant capacity of wheat bran when using the conventional method based on solvent extraction and alkaline and/or acid hydrolysis.

Treatments with Xylanase at High (90 %) and Low (40 %) Water Content Have Different Impacts on Physicochemical Properties of Wheat Bran

The aim of the work was to elucidate the impacts of treatment with xylanase at high (90 %) and low (40 %) water contents on the structural and physicochemical properties of wheat bran. The bran treatments at 40 % water content, both with and without added xylanase, resulted in a smaller average bran particle size, more changes in bran microstructure, and higher solubilization of polysaccharides than the corresponding treatments at 90 %. Also, the water holding capacity of bran (3.6 ± 0.1 g water/g bran dm), determined by Baumann method, decreased more already after 4-h xylanase treatments at 40 % (2.4 ± 0.1) than at 90 % (2.9 ± 0.2). The solubility of salt-extractable bran proteins decreased during the treatments, especially at 40 %, also without added xylanase. Protein aggregation was detected in the SDS + DTT-extractable bran fraction, which also contained small proteins of 10–20 kDa not detectable in the untreated bran. The use of xylanase had only minor effect on bran proteins as compared to the treatments without added xylanase. The results indicate the large role of mechanical shear on the bran properties at 40 % water content. The low arabinose/xylose ratio (0.32) in the bran water extract after 24-h xylanase treatment at 40 %, however, suggests that the solubilization of arabinoxylan was caused by enzymatic action, and not by mechanical degradation. Arabinose/xylose ratio of the bran water extract decreased similarly during all the treatments, suggesting similar solubilization pattern of arabinoxylan at both water contents. The study showed that bran properties can be significantly modified by adjusting the water content and mechanical energy used in processing.

Effect of particle size reduction, hydrothermal and fermentation treatments on phytic acid content and some physicochemical properties of wheat bran.

With the aim of reducing phytic acid content of wheat bran, particle size reduction (from 1,200 to 90μm), hydrothermal (wet steeping in acetate buffer at pH 4.8 at 55°C for 60min) and fermentation (using bakery yeast for 8h at 30°C) and combination of these treatments with particle size reduction were applied and their effects on some properties of the bran were studied. Phytic acid content decreased from 50.1 to 21.6, 32.8 and 43.9mg/g after particle size reduction, hydrothermal and fermentation, respectively. Particle size reduction along with these treatments further reduced phytic acid content up to 76.4% and 57.3%, respectively. Hydrothermal and fermentation decreased, while particle size reduction alone or in combination increased bran lightness. With reducing particle size, total, soluble and insoluble fiber content decreased from 69.7 to 32.1%, 12.2 to 7.9% and 57.4 to 24.3%, respectively. The highest total (74.4%) and soluble (21.4%) and the lowest insoluble fiber (52.1%) content were determined for the hydrothermaled bran. Particle size reduction decreased swelling power, water solubility and water holding capacity. Swelling power and water holding capacity of the hydrothermaled and fermented brans were lower, while water solubility was higher than the control. The amount of Fe(+2), Zn(+2) and Ca(+2) decreased with reducing particle size. Fermentation had no effect on Fe(+2)and Zn(+2) but slightly reduced Ca(+2). The hydrothermal treatment slightly decreased these elements. Amongst all, hydrothermal treatment along with particle size reduction resulted in the lowest phytic acid and highest fiber content.

Effects of microfluidization process on physicochemical properties of wheat bran

Wheat bran is a very important dietary fiber source which is widely used in the food industry in order to produce fiber enriched foods. Previous reports have demonstrated that physicochemical properties of insoluble dietary fibers determine their physiological effects when they are consumed, indicating modification of these properties may improve the fibers' physiological properties. In this study, the microfluidization process was used to treat wheat bran and its effects on the bran's physicochemical properties were examined. The results showed that microfluidization process could effectively decrease particle size and bulk density, and substantially increase specific surface area, water-holding capacity, swelling capacity, oil-holding capacity and cation-exchange capacity. Confocal micrographs showed that the process could also separate the structural components of wheat bran. These results suggested that microfluidization process would provide an effective method to modify physicochemical properties of wheat bran and probably other cereal brans.

Influence of extrusion-cooking on the physico-chemical properties of wheat bran

Wheat bran was extruded under various conditions with a Clextral BC 45 twin screw extruder. Water (6·1–17·5 % of dry solid feed rate) and feed rate (20–32 kg/h) were varied in order to obtain treatments of different severities. These were monitored by the specific mechanical energy measured by the electrical consumption of the main motor drive. The water solubility of the extruded products increased from 20 to 40 % and the soluble fibre content from 8 to 16 %. These values were well correlated to the specific mechanical energy (230–380 kWh/t). Analysis of the sugar composition showed a slight increase in the solubility of glucuronoarabinoxylans arising from the external pericarp layer and a marked increase in the solubility of arabinoxylans and β-glucans probably arising from the aleurone and endosperm cell walls. Water absorption capacity, as measured by the Baumann method, increased from 270 to 375 % for the products processed under low severity treatments.