脱脂麦胚蛋白粉的持水能力和蛋白溶解度试验研究

脱脂麦胚蛋白粉是一种优质植物蛋白资源,采用均匀设计方法研究了ｐＨ值（４．０～８．０）、加热温度（２０～７０℃）和加热时间（１０～３０ｍｉｎ）对其持水能力和蛋白溶解度的影响。随着温度的升高,持水能力显著增强,ｐＨ值的影响相对较小,而温度的影响可以忽略。ｐＨ值为４．０,温度为７０℃时,持水能力最强。ｐＨ值对蛋白溶解度的影响显著,时间的影响可以忽略。ｐＨ值为８．０,温度为２０℃时,蛋白溶解度最大。研究结果还表明,脱脂麦胚蛋白粉可作为食品添加剂以改善食品的营养和品质。     

Effect of Outer Bran Layers from Germinated Wheat Grains on Breadmaking Properties

Wheat grains were germinated in the dark at room temperature (24°C) for 1, 2, 3, 5, and 8 days. Germinated wheat grains were pearled in a Waring blender, and the outer bran layers were separated from the pearled grains. Breadmaking was performed with wheat flour and 10% of the outer bran layer. Breadmaking properties (bread height [mm] and specific volume [cm³/g]) were gradually enhanced by blending the germinated outer bran layers, and maximum specific volume was obtained after 5 days of germination. However, the improvement was lost after 8 days of germination. Rapid ViscoAnalyser (RVA) and Brabender Farinograph profiles of wheat flour and outer bran layers (10%) indicated that the maximum decrease of peak viscosity and increase of angle of tail were obtained after 3 and 5 days of germination, respectively. Those changes are presumed to be due to the action of enzymes found in the outer bran layers. Activities of α‐ and β‐amylase, lipase, protease, and xylanase in the outer bran layers were measured, and correlation coefficients (r) between breadmaking properties and peak viscosity (RVA), angle of tail (farinograph), and enzyme activities were calculated. These data suggest that xylanase and α‐amylase activities in the outer bran layers were highly related to the enhancement of the breadmaking properties.     

Effect of Wheat Bran Fiber and Bran Particle Size on Fat and Fiber Digestibility and Gastrointestinal Tract Measurements in the Rat

The effect of wheat bran (AACC hard red) and bran particle size on fat and fiber digestibility and gastrointestinal tract measurements were investigated with diets containing 5.7–10.7% dietary fiber. Fifty‐six male weanling Sprague‐Dawley rats were randomly assigned to four diets containing 5% cellulose (C5); 10.5% cellulose (C10); 21.5% coarse (2 mm) wheat bran (CB); or 22.2% fine (0.5 mm) wheat bran (FB) in a sixweek study. Dietary fiber digestibilities were significantly different (P < 0.05) among treatment diets (CB > FB > C5 > C10) but there was no effect in fat digestibility among treatments. High‐fiber diets fed to rats resulted in significantly greater wet and dry fecal weights than low‐fiber diets. Bran diets resulted in significantly higher fecal moisture than cellulose diets. Cecum lengths increased significantly with bran diets compared with cellulose diets. The CB diet resulted in significantly higher stomach weights than with cellulose diets. Stomachs were heavier and cecal lengths were greater with bran diets than with cellulose diets; however, a high‐cellulose diet resulted in increased colon weight. Except for higher fiber digestibility of coarse bran, bran particle size had no significant effects. Healthful effects of wheat bran may be associated with gastrointestinal morphology and function. Fecal bulking and decreased intestinal transit time can prevent constipation and may dilute or reduce absorption of toxic or carcinogenic metabolites, thus improving gastrointestinal health and lowering the risk of tumor development and cancer.     

Effect of Wheat Bran on Dough Rheology and Final Quality of Chinese Steamed Bread

Wheat bran is a low‐cost by‐product abundantly produced by the wheat flour industry. As a staple food of China, Chinese steamed bread (CSB) represents about 40% of China's wheat consumption. This study investigated the effects of incorporating wheat bran into the CSB at different levels (5, 10, and 15%). The dough behavior was measured by analyzing rheological properties. Quality of CSB was analyzed from two perspectives: physical properties and nutritional quality. For physical properties, specific volume, loaf height, moisture, and texture were measured by 1 . The predicted glycemic response of the bread was analyzed by using an in vitro digestion method. The results illustrated that the incorporation of wheat bran into wheat flour reduced the extensibility of the dough, decreased specific volume, and increased bread hardness, gumminess, and chewiness. However, this study also showed that addition of wheat bran can decrease the predicted glycemic response of steamed bread by up to 39%.     

Starch Hydrolyzing Enzymes for Retarding the Staling of Rice Bread

Previous attempts have been made to obtain gluten‐free bread of acceptable quality for bread specific volume and crumb texture. Rice bread is a good alternative to celiac patients, but it has a very rapid staling during storage. Rice starch is more prone to retrograde during storage than wheat starch, and the special hydrophobic nature of the rice proteins requires specific enzymes to be used in the rice bread process. To retard rice bread staling, two different starch hydrolyzing enzymes (α‐amylase of intermediate thermostability and cyclodextrin glycoxyl transferase [CGTase]) have been tested and their effect on fresh bread quality and staling during storage has been evaluated. The addition of α‐amylase improved bread specific volume and crumb firmness but very sticky textures were obtained. The addition of CGTase produced even higher specific volume and similar crumb firmness with better texture. Both enzymes decreased the ability of amylopectin to retrograde during storage. The firming kinetic was lowered by the α‐amylase but not the limiting firmness, while the rice crumb from CGTase firmed quickly with a very short range of firmness increase. Results revealed that the starch hydrolysis brought about by the α‐amylase was not sufficient to retard staling. CGTase was considered a better antistaling agent because of its starch hydrolyzing and cyclizing activity.     

In Vitro Binding of Bile Acids by Rice Bran,Oat Bran,Wheat Bran,and Corn Bran

The in vitro bile acid binding by rice, oat, wheat, and corn brans was determined using a mixture of bile acids normally secreted in human bile at a physiological pH of 6.3. The objective of the study was to relate bile acid binding of cereal brans to health promoting properties. Three experiments were conducted testing substrates on an equal weight (dry matter) basis, an equal total dietary fiber (TDF) basis, and an equal TDF and equal fat basis. Each experiment was repeated to validate the results (for a total of six experiments). The relative in vitro bile acid binding of the cereal brans on an equal TDF basis considering cholestyramine as 100% bound was rice bran 51%, wheat bran 31%, oat bran 26%, and corn bran 5%. The data suggest that cholesterol lowering by rice bran appears to be related to bile acid binding. The primary mechanism of cholesterol lowering by oat bran may not be due to bile acid binding by soluble fiber. Bile acid binding did not appear to be proportional to the soluble fiber content of the cereal brans tested. Bile acid binding by wheat bran may contribute to cancer prevention and other healthful properties.     

Reducing Beta-Glucan Solubility in Oat Bran Muffins by Freeze-Thaw Treatment Attenuates Its Hypoglycemic Effect

The viscosity of soluble fibers such as β-glucan depends on their concentration in solution and molecular weight (MW) distribution. We investigated whether freezing treatment of oat bran muffins affected the physicochemical properties of β-glucan, and its physiological effectiveness in lowering postprandial blood glucose response. A controlled range of β-glucan solubility was achieved by subjecting oat bran muffins containing two levels of β-glucan to repeated freeze-thaw temperature cycling. β-Glucan solubilized by in vitro digestion extraction was measured by flow-injection analysis. MW distributions of β-glucan were analyzed using size-exclusion chromatography. β-Glucan solubility decreased as the number of freeze-thaw cycles increased, while MW distribution of β-glucan decreased slightly. Peak blood glucose rise (PBGR) after fresh muffins (8 and 12 g of β-glucan/serving) was significantly lower than that after muffins (8 and 12 g of β-glucan/serving) treated with four freeze-thaw (FT) cycles (1.84 ± 0.2 vs. 2.31 ± 0.1 mmol/L, P = 0.007). Compared with the control whole wheat muffins, the reduction in incremental area under the glucose response curve (AUC) after fresh muffins (8 and 12 g of β-glucan/serving) was nearly twice that after 4 FT cycles (43.3 ± 4.4% vs. 27.0 ± 5.4%, P = 0.016). A significant inverse linear relationship was found between the log [concentration] of extractable β-glucan and PBGR (r² = 0.85, P = 0.01), and AUC (r² = 0.71, P = 0.03). The results show that reduction of β-glucan solubility in foods attenuates its physiological effectiveness in lowering postprandial glycemia.     

The Effect of Bioprocessing on the Phenolic Acid Composition and Antioxidant Activity of Wheat Bran

In the present study, bioprocessing with eight microbial strains including Bacillus species, yeasts, and filamentous fungi was evaluated for its potential to improve the phenolic acid composition and antioxidant activity of wheat bran. The soluble free and soluble conjugated fractions of ethanolic extracts of the treated bran samples were compared for their total phenolic contents, phenolic acid composition, and in vitro antioxidant activities. In general, total phenolic content in the soluble free fraction increased significantly, accounting for 241.11 ± 1.25 μg of gallic acid equivalents (GE)/g (Rhizopus oryzae), 230.50 ± 1.05 μg of GE/g (Mucor circinelloides), and 230.19 ± 1.02 μg of GE/g (Saccharomycopsis fibuligera). The phenolic acid composition, especially of the soluble free fraction, was improved most by S. fibuligera (hydroxybenzoic, vanillic, syringic, and trans‐ferulic acids), M. circinelloides (chlorogenic acid), and R. oryzae (protocatechuic, trans‐coumaric, and benzoic acids). Comparatively, bioprocessing exhibited less effectiveness on conjugated phenolic acid composition. Fermented wheat bran displayed enhanced reducing capacity, superoxide anion radical scavenging activity, and 1,1‐diphenyl‐2‐picrylhydrazyl radical scavenging activity in comparison with the nonfermented sample. The antioxidant activity was significantly correlated to the total phenolic content.     

硫肥对小麦蛋白质组分及产量的影响

试验在高肥力而硫素极缺的土壤上进行了试验,在施用常规氮磷钾肥料的基础上,比较不同小麦品种施硫肥与不施硫肥对小麦蛋白质组分及产量的影响。结果表明:在常规肥料措施下增施硫肥,提高了小麦营养体及籽粒中的含氮量,显著提高了籽粒中醇溶蛋白及总蛋白含量,而且不同蛋白质含量的小麦对硫肥的反应存在差异.施用硫肥极显著降低了千粒重和容重,产量也有所下降,但未达显著水平。     

Effect of a Wheat Protein on pH-Dependent Water-Binding Capacity and Viscosity of Wheat Tailings Fractions

Wheat flour was fractionated with acetic acid using a mortar and pestle method or a blender method. Higher pH-dependent water-binding capacity (WBC) and viscosity were obtained only in the tailings fraction. The higher pH-dependent WBC was rather stable at 5–37°C, however it decreased with salt addition. Pepsin or bromelain treatment stopped the pH-dependent changes in WBC and viscosity, which suggests that this characteristic of the tailings fraction is due to the presence of proteins. HPLC indicated that the M_r of the proteins associated with high WBC at low pH was >200 kDa.     

Influence of Added Enzymes and Bran Particle Size on Bread Quality and Iron Availability

The aim of this investigation was to study the influence of different bran proportions and particle sizes, addition of fungal phytase, and α‐amylase addition on bread quality and phytate levels, and how these treatments affect availability of iron to intestinal epithelial (Caco‐2) cells. Potential mineral contributions to dietary reference intakes and phytate‐to‐mineral molar ratios were also evaluated. Wheat bran supplementation significantly affected bread quality. Smaller bran particle size affected crumb firmness negatively, whereas the use of α‐amylase, in some cases in combination with phytase, could improve technological bread quality. The use of phytase in the formulation significantly reduced the level of phytates, and phytate hydrolysis also led to smaller bran particle size. Increasing the bran proportion used in the bread formulation increased the iron concentration in bread samples by 18.9%. Phytase addition proved to be a useful strategy to improve iron dialyzability; however, incomplete dephytinization still had an inhibitory effect on iron uptake, with the exception of samples formulated with 10% bran. The inhibitory effect of phytate could be predicted from the values of the phytate‐to‐iron ratios. Reduction of particle size did not improve iron availability or uptake by Caco‐2 cells.     

Influence of Bioprocessed Wheat Bran on the Physical and Chemical Properties of Dough and on Wheat Bread Texture

The aim of this work was to assess the influence of wheat bran addition on the rheological properties of dough and on subsequent wheat bread volume and texture. Two types of bioprocessed bran (fermentation with yeast or with yeast plus enzymes) were studied in breadmaking at a substitution level of 20% (sufficient to deliver 6 g of dietary fiber per 100 g of product, the minimum for the European Food Safety Authority high‐fiber nutrition claim). Fermentation activated endogenous enzymes of bran, which together with exogenous enzymes modified the state of fiber in bran, resulting in solubilization of arabinoxylans and slight degradation of the insoluble fiber. Fermentation and enzyme treatment of bran compensated for the increased hardness (+100%) and the volume‐decreasing (–21%) effect observed with untreated bran. Analysis with partial least squares regression suggested the efficacy of bioprocessing to be based on solubilization of arabinoxylans, smaller particle size of bran, lower pasting viscosity of starch, improved resistance to extension, and accelerated CO₂ production.     

In Vitro Bile Acid Binding Capacity of Milled Wheat Bran and Milled Extruded Wheat Bran at Five Specific Mechanical Energy Levels

The in vitro binding of bile acids of milled wheat bran (MWB) and milled extruded wheat bran (MEB) at five specific mechanical energy (SME) levels of 120 (MEB‐120), 177 (MEB‐177), 234 (MEB‐234), 291 (MEB‐291), and 358 (MEB‐358) Whr/kg on a fat‐free dry weight basis was determined using a mixture of bile acids secreted in human bile at duodenal physiological pH 6.3. Relative to cholestyramine (bile acid binding, cholesterol lowering drug) in vitro bile acid binding capacity on dry matter, total dietary fiber (TDF), and insoluble dietary fiber (IDF) basis was for MWB: 21, 43, 45%; the range for MEB was 18–21%, 34–41%, and 36–43%, respectively. MWB resulted in significantly higher bile acid binding than that of MEB at 120, 234, and 291 Whr/kg on a dry matter, TDF, and IDF basis. These results demonstrate the relative health‐promoting potential of MWB = MEB‐177 = MEB‐358 > MEB‐120 = MEB‐234 = MEB‐291 as indicated by the bile acid binding on a dry matter basis. Data suggest that significant improvement in health‐promoting (cholesterol‐lowering and cancer‐preventing) potential could be obtained in WB by milling (low‐cost processing) the bran to finer particle sizes and extruding (high‐cost technology). Milling WB to small particle size (weighted mean 0.508 mm) increased surface area, in addition it may have induced changes in the physical and chemical characteristics of WB or created new linkages, binding sites of the proteins, starches, and nonstarch polysaccharides, which significantly increased the bile acid binding ability of the MWB.     

Evolution of the Levels of Free Radicals Generated on Wheat Flour and Wheat Bran by Electron Beam

This paper presents the experimental data regarding the levels of free radicals investigated by electron spin resonance (ESR) on wheat flour and wheat bran exposed to an electron beam. Samples were irradiated with an electron linear accelerator of 6 MeV and then stored at room temperature in air. ESR spectra of the samples indicated presence of free radicals induced by electron beam. Three types of free radicals have been detected in wheat flour, and signals typical for cellulose‐like radicals have been noticed for wheat bran, their concentration increasing with the irradiation dose. The postirradiation storage of both sample types caused radical decay with a two‐step pattern associated with fast decay of short‐life radicals followed by slow reduction of long‐life radicals. However, in the first step, the irradiated wheat bran exhibited more rapid decay of radicals than irradiated flour owing to their different complex matrixes, which led to paramagnetic structures of different origin after exposure to an electron beam. The ESR technique allows the detection of free radicals induced in wheat flour and bran by electron beam for a limited period after irradiation that could be shorter than the shelf life of the products.     

Effect of Protein Quality,Protein Content,Bran Addition,DATEM, Proving Time,and Their Interaction on Hearth Bread

The effect of protein quality, protein content, bran addition, diacetyl tartaric acid ester of monoglycerides (DATEM), proving time, and their interaction on hearth bread characteristics were studied by size‐exclusion fast protein liquid chromatography, Kieffer dough and gluten extensibility rig, and small‐scale baking of hearth loaves. Protein quality influenced size and shape of the hearth loaves positively. Enhanced protein content increased loaf volume and decreased the form ratio of hearth loaves. The effect of protein quality and protein content was dependent on the size‐distribution of the proteins in flour, which affected the viscoelastic properties of the dough. Doughs made from flours with strong protein quality can be proved for a longer time and thereby expand more than doughs made from weak protein quality flours. Doughs made from strong protein quality flours tolerated bran addition better than doughs made from weak protein quality flours. Doughs made from high protein content flours were more suited for hearth bread production with bran than doughs made from flours with low protein content. DATEM had small effect on dough properties and hearth loaf characteristics compared with the other factors.     

Effect of Extrusion on Hypocholesterolemic Properties of Rice,Oat, Corn,and Wheat Bran Diets in Hamsters

Brans from rice, oats, corn, and wheat were cooked in a twin-screw extruder at either high or low energy input, and their cholesterol-lowering effects were compared with those of unprocessed brans when fed to four-week-old male golden Syrian hamsters (n = 10 per treatment) for three weeks. Peanut oil was added to oat, corn, and wheat bran during the extrusion process to match the oil content of rice bran. Diets contained 10% total dietary fiber, 10.3% fat, 3% nitrogen, and 0.3% cholesterol. Plasma and liver cholesterol and total liver lipids were significantly lower with low-energy extruded wheat bran compared with unprocessed wheat bran. Extrusion did not alter the hypocholesterolemic effects of rice, oat, or corn brans. Plasma and liver cholesterol levels with corn bran were similar to those with oat bran. Relative cholesterol-lowering effects of the brans, determined with pooled (extruded and unextruded) bran data, were rice bran > oat bran > corn bran > wheat bran. Rice bran diets resulted in significantly lower levels of total plasma cholesterol and very low density lipoprotein cholesterol compared with all other brans. Total liver cholesterol and liver cholesterol concentrations (mg/g) were significantly lower with high-energy extruded rice bran compared with the cellulose control group. Plasma cholesterol and total liver cholesterol values with low-energy extruded wheat bran were similar to those with rice bran (unextruded or extruded) diets. Lowered cholesterol with rice bran diets may result in part from greater lipid and sterol excretion with these diets. Results with low-energy extruded wheat bran suggest that this type of processing may improve the potential for lowering cholesterol with wheat bran products.     

麦麸酯酶对有机磷及氨基甲酸酯类农药敏感性研究

为探讨麦麸酯酶在农残快速检测中应用的可行性,通过比色法研究了酶抑制法检测农残时表面活性剂对固蓝B盐显色体系的增敏作用及麦麸酯酶对乐果、敌敌畏、叶蝉联、西维因、丁硫克百威和甲基对硫磷等6种农药的灵敏度和最低检测限。结果表明,阴离子表面活性剂SDS在麦麸酯酶活性测定中具有增敏作用,当浓度为4.0%时可使显色体系相对吸光度值增加152.76%;叶蝉散对麦麸酯酶的最佳抑制时间为40min,其余5种农药均为30min。麦麸酯酶对6种农药的灵敏度大小顺序为:敌敌畏叶蝉散西维因甲基对硫磷丁硫克百威乐果,IC_(50)分别为0.136、0.375、0.641、1.366、2.361、2.651mg·L~(-1)。经溴水氧化的甲基对硫磷对麦麸酯酶的敏感性显著提高,其IC_(50)值达0.089mg·L~(-1)。综上所述,麦麸酯酶在快速检测有机磷及氨基甲酸酯类农药方面具有较高的灵敏度,且来源广泛,可满足酶抑制法用酶需要。本研究丰富了麦麸酯酶在农药残留快速检测中的应用。     

褐斑病侵染下2,3-丁二醇-凹凸棒石复合制剂对草地早熟禾细胞壁组成物质及细胞壁降解酶活性的影响

为了探究2,3-丁二醇(2,3-BD)与凹凸棒石(PAL)复合使用对植物诱抗能力的提升效果,以草地早熟禾纳苏(Poa pratensis Nassau)为试验材料,2,3-BD-PAL为复合诱导制剂,立枯丝核菌(Rhizoctonia solani)为接种病原物,对未诱导接菌、2,3-BD诱导接菌和2,3-BD-PAL复合诱导接菌后的植株叶片中细胞壁组成物质及细胞壁降解酶活性进行数据分析。结果表明,在病原菌胁迫期间,各处理组植株叶片中羧甲基纤维素酶(Cx)、β-葡萄糖苷酶(β-Glu)、滤纸酶(FPA)、果胶甲基半乳糖醛酸酶(PMG)和多聚半乳糖醛酸酶(PG)活性均显著升高,而多聚半乳糖醛酸反式消除酶(PGTE)和果胶甲基反式消除酶(PMTE)活性变化不明显,其中Cx起主要降解作用。在胁迫3 d时,未诱导叶片Cx、β-Glu和PG等酶活性快速上升到最大值,而诱导处理有效抑制了酶活的增加。草地早熟禾经2,3-BD-PAL复合诱导处理后,能够稳定纤维素含量,高效促进果胶合成和木质素积累,抑制菌丝入侵,更大程度上降低Cx、β-Glu和PG等降解酶对细胞壁的破坏程度,其诱抗效果优于2,3-BD单独诱导处理。综上,2,3-BD与PAL复合诱导能够增强2,3-BD的诱导效果,提高植物抗病性,为2,3-BD在农业生产中的广谱性应用奠定了理论基础。     

Cholesterol Response and Foam Cell Formation in Hamsters Fed Rice Bran,Oat Bran,and Cellulose + Soy Protein Diets With or Without Added Vitamin E

Four-week-old male golden Syrian hamsters were fed diets containing cellulose (control, CC), cellulose + soy protein (CS), CS + vitamin E, (CSE), rice bran (RB), RB + vitamin E (RBE), oat bran (OB), and OB + vitamin E (OBE) for six weeks (n = 10/treatment). Diets contained (by weight) 10% total dietary fiber, 3% N, 20% fat, 0.5% cholesterol, and some diets had an additional 0.1% vitamin E. After six weeks, RB and OB diets resulted in significantly higher weight gain than the CC diet. Plasma low-density lipoprotein cholesterol (LDL-C) values and the LDL-C/high-density lipoprotein cholesterol ratio in hamsters fed CSE, RBE, OB, and OBE diets were significantly lower than in those fed CC diet. There were no significant differences in total plasma cholesterol values among the hamsters fed any of the diets. Liver cholesterol in animals fed OB and OBE diets was significantly lower than in all other groups. Foam cell areas in the inner bend of the aortic arch in animals fed all treatment diets were significantly reduced when compared with that in animals fed CC diet. The level of additional dietary vitamin E did not result in further significant reductions in foam cell area. The results of this study suggest that diets containing rice bran, oat bran, or soy protein significantly reduced the development of atherosclerosis in hypercholesterolemic hamsters.     

Determination of Bran Contamination in Wheat Flours Using Ash Content,Color, and Bran Speck Counts

A fast new method based on image analysis, ScanPro Speck Expert (SPX), to determine the bran contamination in wheat flour was studied and compared with existing methods (air-oven, ash, and color measurements) using an Agtron color meter and a Minolta chromameter. Twenty-one hard red winter wheat flour samples with ash contents of 0.30–0.58% were collected from the Kansas State University pilot mill and used for this study. Intrinsic variability in the flour sample because of randomness of bran speck orientation and distribution in the sample holder could result in variation in the speck count. Simple and multiple linear regression analyses showed that estimation of flour ash content from the SPX results (R² = 0.91) would be more accurate than the results from color measurements (R² = 0.66 [Agtron color meter] and 0.74 [L*]). The added capability of SPX image analyzer to not only count the number of bran specks but also to measure their areas probably increases the accuracy of determining the bran contamination in wheat flour by image processing.