Effect of endo‐xylanase‐containing enzyme preparations and laccase on the solubility of rye bran arabinoxylan

Three commercial enzyme preparations with endo‐xylanase activity, namely Bio‐Feed Wheat, Bio‐Feed Plus and Grindamyl H 640, and laccase have been tested for their effects on the solubilisation of arabinoxylan (AX) in rye bran or autoclaved rye bran. Autoclaving efficiently increased the availability of AX for enzymatic degradation. Both Bio‐Feed Wheat (a monocomponent enzyme) and Bio‐Feed Plus (a multicomponent preparation with different enzymatic activities) efficiently degraded the autoclaved rye bran AX into lower‐molecular‐weight fragments. As much as 70% of the xylose residues and 58% of the arabinose residues in the autoclaved bran were soluble after treatment with Bio‐Feed Plus; the weight—average molecular weight of the detectable portion of these soluble polymers was 104 000 Da. Grindamyl H 640 solubilised only a small fraction of the AX in autoclaved rye bran; the molecular weight of these soluble fragments was higher than that of those released by the Bio‐Feed xylanases. Addition of laccase during treatment with Bio‐Feed Wheat or Grindamyl H 640 decreased the yield of water‐soluble AX. © 2003 Society of Chemical Industry     

Effects of enzymes in fibre-enriched baking

The aim of the present study was to improve the quality of fibre-enriched wheat breads by enzymic treatment of the fibre fraction. The suitability of different enzymes in fibre-enriched baking and their effects on the dietary fibre content and the ratio of insoluble: soluble fibre content of the breads were studied. The enzyme preparations used were a hemicellulolytic culture filtrate of Trichoderma reesei, a specific (pI 9) xylanase of T reesei and Fermizyme, an α-amylase preparation containing a standardised level of hemicellulase activity. Rye bran was extracted in water (10% (w/w) suspension) to determine the solubilities of the β-glucans and pentosans. Addition of T reesei culture filtrate significantly increased the amount of extractable pentosan obtained from nonautoclaved rye bran. Rye bran supplementation (5%) of wheat flour increased the farinograph absorption and dough development time, but had little or no effect on stability and softening of the dough. The added enzymes decreased dough stability and increased softening. Addition of enzymes caused significant differences in the stickiness of the wheat doughs both with (P<0·003) and without (P<0·001) rye bran. Fermizyme significantly increased the stickiness of wheat doughs both with and without rye bran. The baking results of the fibre-enriched breads were improved by the added enzymes. Addition of T reesei culture filtrate increased the specific volume of the wheat breads both with and without rye bran by almost 20%. Enzyme mixtures were more efficient than individual xylanase in softening the bread crumb and reducing the staling rate of wheat breads both with and without rye bran. Incorporation of enzymes reduced the total dietary fibre content of the breads, but at least doubled the amount of soluble pentosan. The proportions of fluorescent cell walls in the breads were detected by microscopical image analysis. Enzyme addition caused the surface area of insoluble cell walls originating from wheat flours to decrease, suggesting that the enzymes exert more effects on wheat endorsperm cell walls than on bran particles. © 1998 SCI.     

The effects of cereal additives in low-fat sausages and meatballs. Part 1: Untreated and enzyme-treated rye bran

Rye bran was added to frankfurter-type sausages and meatballs with the aim of producing low-fat products with increased dietary fibre content. The addition of untreated rye bran to sausages was detrimental, causing a substantial increase in frying loss (20% compared to 13.2%). The addition of rye bran treated with hydrolytic enzymes reduced the frying loss to 15.2–16.4%. The firmness was also improved by the treatments (12.8–14.2 N compared to 8.8 N). Enzymatic treatment of rye bran did not however improve the water-holding capacity or the texture of sausages compared to the rye bran that had only been soaked in water. The reason could be that enzymes degraded the solubilized fraction of the dietary fibre, leaving small fragments that cannot contribute to the water-holding capacity and the texture of the sausages. The benefits of treating rye bran in water were not seen in meatballs, probably due to the more particulate structure of meatballs, which is not as sensitive to additives.     

Antioxidant activity and dietary fibre in durum wheat bran by-products

Milling of wheat generates by-products, which can be used to improve the technological performance and/or to integrate foods with healthy compounds. The aim of this paper was to select fractions of durum wheat bran having different functional and nutritional characteristics. Wheat bran by-products were obtained by an industrial milling process. Beside the single fractions, two commercial products Bran & Brain 50 and 70, obtained by blending some of the durum wheat fractions were also studied. All samples were investigated for water holding capacity, soluble and insoluble dietary fibre content and for their antioxidant activity. The soluble fibre content of the durum wheat by-product ranged between 0.9% and 4.1%; while that of insoluble fibre between 21% and 64%. B&B 70 has a TDF content of 61%, while B&B 50 has 42%. The water holding capacity of each fraction is strictly related to the amount of insoluble fibre and to the granulometry of the by-products. Cooking-extrusion process does not affect the amount of soluble fibre; by contrast, a significant increase of the insoluble fibre was detected. The antioxidant activity is higher for the internal bran fraction and it increases in fractions having reduced granulometry. The antioxidant activity of some durum wheat by-product fractions is comparable to that of widespread fruits and fresh vegetables, likely due to the presence of fibre-bound phenol compounds. The high fibre content and antioxidant activity of durum wheat bran by-products can be of particular interest for their use in cereal-based products.     

Effects of enzymatic treatment conditions on dietary fibre content of wheat bran and use of cellulase-treated bran in cookie

A commercial cellulase preparation (Viscozyme Cassava C) was employed to process wheat bran to improve the ratio of insoluble to soluble dietary fibre. The effects of initial moisture content, enzyme dosage, and incubation time on the content of soluble and insoluble fibre during the enzymatic treatment were investigated. The appropriate conditions for the cellulase treatment were initial moisture content of 0.75 g water g⁻¹ dry matter, enzyme dosage of 9 U g⁻¹ dry matter and incubation time of 120 min under which the ratio of insoluble to soluble fibre of wheat bran was lowered by 42%. Untreated and cellulase-treated wheat bran was incorporated into cookies at levels of 0%, 20%, 30%, 40% and 50%. Cookie with 50% cellulase-treated bran showed 21% lower ratio of insoluble to soluble fibre as well as 14% lower hardness and 13% higher overall acceptability than sample with the same amount of untreated bran.     

小米麸皮膳食纤维成分及物化特性测定

本试验采用酶-化学法提取糯性小米麸皮、非糯性小米麸皮中的膳食纤维,对其化学成分、单糖组成进行分析,并对提取出的膳食纤维进行物化特性测定,包括膨胀力、持水力、持油力等。结果表明,糯性麸皮中膳食纤维质量分数达到76.58%,其中不溶性膳食纤维为69.09%,可溶性膳食纤维为7.49%;非糯性小米麸皮中膳食纤维质量分数为73.18%,其中不溶性膳食纤维为65.55%,可溶性膳食纤维为7.63%;提取出的糯性和非糯性小米麸皮膳食纤维中不溶性膳食纤维质量分数分别达到91.35%、89.55%。且从小米麸皮中提取出来的膳食纤维均具有良好的物化特性3,7℃下,糯性小米麸皮膳食纤维和非糯性小米麸皮膳食纤维膨胀力分别为4.80、4.61 mL/g。这些都标示着小米麸皮可作为富含大量优质膳食纤维的潜在来源。     

小麦麸皮膳食纤维挤压加工工艺研究

以小麦麸皮膳食纤维为原料,采用双螺杆挤压机对其进行挤压加工,以提高小麦麸皮膳食纤维中可溶性膳食纤维的含量。研究了挤压温度、物料含水量和螺杆转速对原料中可溶性膳食纤维含量的影响,研究结果表明:麸皮含水量20%,挤压温度170℃,主机转速185 r/min时,麸皮原料中可溶性膳食纤维含量由3.22%提高到10.14%。通过高效液相色谱、扫描电镜检测及持水力与膨胀力试验显示,加压处理可以有效地增加可溶性膳食纤维的含量,以及改变麸皮的表面结构。     

米糠贮藏时间对米糠不溶性膳食纤维功能性质的影响

以新鲜米糠为原料,分别贮藏0、1、3、5、10 d稳定化和脱脂后制备米糠不溶性膳食纤维,研究米糠贮藏时间对米糠不溶性膳食纤维功能性质的影响。结果表明:随着米糠贮藏时间的延长,米糠不溶性膳食纤维的持水性、持油性、阳离子交换能力和吸附胆酸钠能力先上升后下降,分别在新鲜米糠贮藏1、3、1 d和3 d达到最大值,分别为4.75 g/g、4.10 g/g、0.39 mmol/g和42.54 mg/g。随新鲜米糠贮藏时间的延长,米糠不溶性膳食纤维的结合水力逐渐下降,膨胀力无显著性变化,粉体亮度先上升后下降。研究表明米糠短期贮藏可以改善米糠不溶性膳食纤维的部分功能性质,而长期贮藏会引起米糠不溶性膳食纤维功能性质的下降。     

超高静压改性麦麸对其功能性质的影响

本实验以小麦麸皮为原料,采用单因素试验研究麦麸粒度、处理时间、处理压强和改性麦麸质量分数对小麦麸皮功能性质的影响,通过扫描电子显微镜和傅里叶变换红外光谱仪分析了麦麸改性前后的超微结构和官能团。结果：在麦麸粒度40 目、处理时间20 min、压强400 MPa、麦麸质量分数20%条件下,麦麸可溶性膳食纤维质量分数最高、阳离子交换能力最强、脂肪酶活力最低;在麦麸粒度50 目、处理时间15 min、压强400 MPa、麦麸质量分数20%条件下,麦麸持水力和持油力较高;在麦麸粒度40 目、处理时间25 min、压强300 MPa、麦麸质量分数15%条件下,麦麸亚硝酸根清除率较强;在麦麸粒度50 目、处理时间25 min、压强500 MPa、麦麸质量分数25%条件下,麦麸胆固醇吸附能力较强。扫描电子显微镜观察结果显示超高静压破坏了麦麸膳食纤维的结构,使其结构变得疏松,傅里叶变换红外光谱分析结果表明超高静压可以破坏分子间的共价键,使纤维素降解,不溶性膳食纤维转化为可溶性膳食纤维。通过本实验改性的麦麸具有较好的功能特性,有很好的应用前景。     

Water‐holding capacity of insoluble fibre decreases free water and elevates digesta viscosity in the rat

BACKGROUND: The relationships between possible physiological properties of insoluble fibre and the viscosity of digesta are poorly understood. The aim of this study was to investigate the effect of insoluble fibres with different water‐holding capacity, swelling, oil‐holding capacity and cation exchange capacity on gastric, small intestinal and caecal contents in rats fed a semi‐purified diet containing either no fibre (control), 50 g kg^?1 tossa jute fibre or 50 g kg^?1 shiitake fibre. RESULTS: The water‐holding capacity, swelling, oil‐holding capacity and cation exchange capacity of insoluble fibres of tossa jute were higher than those of shiitake (P < 0.001). The order of the viscosities of digesta was control group < shiitake fibre group < tossa jute fibre group in gastric, small intestinal and caecal contents (P < 0.05). The digesta viscosity at a shear rate of 40 s^?1 was strongly correlated with the free water content of digesta (r = ? 0.89; P < 0.01). The free water content of digesta depended on the water‐holding capacity of insoluble fibres represented as a linear function with negative slope (P < 0.001). CONCLUSION: The viscosity of digesta depends on the free water content, and this is reduced by fibre that holds water and can swell. Copyright © 2008 Society of Chemical Industry     

Effects of extrusion cooking on the dietary fibre content and Water Solubility Index of wheat bran extrudates

Instant study was an attempt to elucidate the suitability of wheat bran for extrusion cooking and to check the effect of different extrusion parameters on the dietary fibre profile as well as on water solubility index. Response surface methodology was used to optimise the extrusion parameters. From results, it was concluded that extrusion cooking had a positive effect on total and soluble dietary fibre. Whilst the insoluble dietary fibre decreased appreciably with the varying processing parameters, the decrease in insoluble fibre and increase in soluble fibre were probably due to disruption of covalent and noncovalent bonds in the carbohydrate and protein moieties leading to smaller and more soluble molecular fragments. Additionally, water solubility index was greatly enhanced by varying extrusion temperature and screw speed. Conclusively, the findings suggest the usefulness of extrusion cooking to beneficially modify the wheat bran for value addition.     

玉米皮膳食纤维性质的研究

以玉米皮为原料,分别制备A(玉米皮水不溶性膳食纤维)和B(混合玉米皮膳食纤维)。通过对比A和B的持水力、膨胀力、吸油力以及对胆固醇、亚硝酸根离子的吸附能力这些指标来研究玉米皮膳食纤维的性质。试验结果表明:B的性能优于A。B的持水力和吸油力比A分别高出20.21%和9.87%;A的膨胀力比B高出4.14%;随着pH值的不断增大,膳食纤维对胆固醇的吸附能力增强,在pH7时B对胆固醇的吸附能力比A提高了约33.33%;溶液中残余亚硝酸根离子的浓度随着时间延长而呈下降趋势,并且pH值对样品吸附亚硝酸根离子的能力有较大的影响,在60 min时A和B在pH2时吸附亚硝酸根离子的浓度均比在pH7时高出46.72μmol/L。     

In vitro fermentation of polysaccharides of rye,wheat and oat brans and inulin by human faecal bacteria

The in vitro fermentabilities of rye, wheat and oat brans and of a commercial fibre preparation, inulin, were compared. The brans were first digested enzymatically to remove starch and protein. The digested brans and inulin were then fermented with human faecal inoculum. The progress of fermentation was studied by following the consumption of carbohydrates and the production of short‐chain fatty acids and gases. Inulin, a short fructose polymer, was consumed significantly faster than the more complex carbohydrates of cereal brans. Carbohydrates of oat bran (rich in β‐glucan) were consumed at a higher rate than those of rye and wheat brans (rich in arabinoxylan). In all brans, glucose was consumed faster than the other main sugars, arabinose and xylose, and arabinose was degraded only slightly. The total production of short‐chain fatty acids was slightly higher with oat bran than with rye and wheat brans and inulin. In the fermentation of inulin, relatively more butyric acid and less propionic acid were produced than in the fermentation of brans. The decrease in pH was also greater in the case of inulin. Wheat bran led to a slightly slower gas formation than rye and oat brans. Formation of gases was fastest and greatest in the case of inulin. In conclusion, rye, wheat and oat brans were fermented in a rather similar way. Fermentation of the brans was different from that of inulin. Cereal brans might serve as a more balanced source of dietary fibre supplement than gas‐producing, readily fermentable polysaccharides such as inulin. © 2000 Society of Chemical Industry     

Effect of Different Extrusion Parameters on Dietary Fiber in Wheat Bran and Rye Bran

Wheat bran and rye bran are mostly used as animal feed today, but their high content of dietary fiber and bioactive components are beneficial to human health. Increased use of bran as food raw material could therefore be desirable. However, bran mainly contains unextractable dietary fiber and deteriorates the sensory properties of products. Processing by extrusion could increase the extractability of dietary fiber and increase the sensory qualities of bran products. Wheat bran and rye bran were therefore extruded at different levels of moisture content, screw speed and temperature, in order to find the optimal setting for increased extractability of dietary fiber and positive sensory properties. A water content of 24% for wheat bran and 30% for rye bran, a screw speed of 400 rpm, and a temperature of 130 °C resulted in the highest extractability of total dietary fiber and arabinoxylan. Arabinoxylan extractability increased from 5.8% in wheat bran to 9.0% in extruded wheat bran at those settings, and from 14.6% to 19.2% for rye bran. Total contents of dietary fiber and arabinoxylan were not affected by extrusion. Content of β‐glucan was also maintained during extrusion, while its molecular weight decreased slightly and extractability increased slightly. Extrusion at these settings is therefore a suitable process for increasing the use of wheat bran and rye bran as a food raw material.     

挤压蒸煮加工米糠可溶和不溶膳食纤维对米淀粉性质的影响及其相互作用分析

研究未挤压、挤压蒸煮加工米糠可溶和不溶膳食纤维对米淀粉糊化性质、热性质、回生性质、结晶性质、微观结构的影响,并采用质构分析、核磁共振、傅里叶变换红外光谱等方法探究挤压蒸煮米糠膳食纤维与米淀粉之间的相互作用。结果表明：与未挤压蒸煮加工米糠膳食纤维相比,挤压蒸煮加工米糠可溶和不溶膳食纤维分别使米淀粉的崩解值显著增加了74.09%和128.36%,并均显著降低米淀粉的峰值黏度、谷值黏度、终值黏度、峰值时间、糊化温度。米糠经过挤压蒸煮加工后,米糠可溶膳食纤维使淀粉凝胶的自由水向强结合水转化,米糠不溶膳食纤维使淀粉凝胶的自由水向弱结合水转化。与未挤压蒸煮加工相比,挤压蒸煮加工米糠可溶和不溶膳食纤维分别使米淀粉的回生值降低了62.59%和44.81%,也均降低了米淀粉凝胶的回生率、相对结晶度、硬度、内聚性、回复性、胶黏性、咀嚼性、1 047 cm－1与1 022 cm－1处吸收峰的峰高比,添加挤压蒸煮米糠可溶、不溶膳食纤维的淀粉凝胶表面较光滑,凝胶结构出现较大的裂缝,说明挤压蒸煮加工米糠提高了米糠膳食纤维对米淀粉回生的抑制效果,且挤压蒸煮可溶膳食纤维比挤压蒸煮不溶性膳食纤维效果好。     

高活性玉米膳食纤维的制备、性质与应用

以玉米种皮为原料,采用酶法制得高活性玉米膳食纤维（ＨＡＦＣ）,含有１２．６９％水溶性纤维,４４．８１％半纤维素,１３．０５纤维素与７．０４％木质素,膨胀力与持水力分别为６．５ｍｌ／ｇ和６２０％。详细论述了玉米膳食纤维的制备方法,化学成分、物化性质及在食品中的应用。     

Antioxidant activity of feruloylated oligosaccharides from wheat bran

Ferulic acid, the main phenolic acid in wheat bran, is esterified to arabinose residues in the cell wall arabinoxylan. Treatment of wheat bran insoluble dietary fibre with xylanases from Bacillus subtilis released feruloylated oligosaccharides, which were purified with Amberlite XAD-2. The antioxidant activity of such oligosaccharides was evaluated using the assay system for erythrocyte hemolysis mediated by peroxyl free radicals generated from 2,2^′-azobis-2-amidinopropane dihydrochloride (AAPH) under in vitro conditions. The feruloylated oligosaccharides inhibited hemolysis of erythrocytes in a dose-dependent manner with 91.7% inhibition of erythrocyte hemolysis at 4 mg/ml.     

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

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 < 0.05) decreased and a redistribution of fiber components from insoluble to soluble fractions was observed. The antioxidant activities of wheat bran and DF before and after grinding were in terms of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, ferrous ion-chelating activity, reducing power and total phenolic content (TPC). Compared with DF before and after grinding, micronized insoluble DF showed increased chelating activity, reducing power and TPC yet decreased DPPH˙ radical scavenging activity. Positive correlations were detected between chelating activity, reducing power and TPC.     

糯小米脱脂米糠的超微粉体性质研究

以脱脂小米米糠为原料,对其粉碎、过筛后粉体的性质进行全面分析,为深度开发小米米糠提供依据。结果表明:脱脂后随粉体粒度的减小,小米米糠粉中的蛋白质、脂肪、淀粉和灰分的含量均有少量增加,总膳食纤维含量有所减少,可溶性膳食纤维含量增加;流动性变差但均匀性更好;持水力、保水力和膨胀力有所下降,水溶性增强,持油力先增大后减小;黏度减小,粉体的颜色变浅,对重金属离子的吸附能力、胆固醇的吸附能力有所下降,阳离子交换能力先升高后下降;DPPH·清除能力、还原力以及螯合铁离子能力均有一定程度的增大。     

Application of common wheat bran for the industrial production of high‐fibre pasta

The study was conducted on the effect of the addition of common wheat bran on the chemical composition, physical properties, cooking quality and sensory traits of durum wheat pasta. The pasta was produced on an industrial scale, applying an addition of common wheat bran at doses ranging from 20 to 40%. The products obtained were compared to the pasta from whole‐grain durum wheat flour, produced under identical conditions and with commercially available whole‐grain durum wheat pasta. The increase in the content of wheat bran in the pasta caused a significant increase (Duncan test, P ≤ 0.05) of the content of protein, lipids, ash and total dietary fibre (TDF). The application of 25–30% addition of common wheat bran allowed obtaining the products which are as rich in dietary fibre as the pasta prepared at the same technological parameters from whole‐grain durum flour. The pasta containing up to 30% of bran was characterised with lower losses of dry mass and higher resistance to overcooking, in comparison with the pasta made of whole‐grain durum. Simultaneously, the products had very good sensory quality.