In Vitro Bile Acid Binding Capacity of Wheat Bran with Different Particle Sizes

The bile acid binding capacity of wheat bran with different particle sizes was determined. Unmilled wheat bran with an average particle size of 900 μm (WB‐900), milled wheat bran at two particle sizes, 500 and 200 μm (WB‐500 and WB‐200), and all three bran samples washed with water (WWB‐900, WWB‐500, and WWB‐200) were mixed with bile acids at pH 6.3 to determine their in vitro adsorption capacity. On a dry matter basis, the order of relative bile acid binding values was WB‐900 ∼ WB‐500 > WWB‐900 > WB‐200 > WWB‐500 > WWB‐200. Data suggests that the surface area as measured by the Brunauer–Emmett–Teller (BET) method and water holding capacity may significantly affect the bile acid binding capacity of wheat bran. As the BET surface area increased with decreasing particle size, the water holding capacity and bile acid binding decreased. Bile acid binding capacity of wheat bran appears to be linked to the ability of the samples to physically adsorb the bile acids. Bile acid binding capacity significantly decreased with reduction in particle size of wheat bran after water washing.     

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.     

In Vitro Binding of Bile Acids by Rice Bran,Oat Bran,Barley and β‐Glucan Enriched Barley

The in vitro bile acid binding by rice bran, oat bran, dehulled barley, and β‐glucan enriched barley was determined using a mixture of bile acids at a duodenal physiological pH of 6.3. Six treatments and two blank incubations were conducted testing substrates on an equal protein basis. The relative in vitro bile acid binding of the cereal brans on an equal total dietary fiber (TDF) and insoluble dietary fiber (IDF) basis considering cholestyramine as 100% bound was rice bran 45 and 49%; oat bran 23 and 30%; dehulled barley 33 and 57%; and β‐glucan enriched barley 20 and 40%, respectively. Bile acid bindings on equal protein basis for the respective cereals were 68, 26, 41, and 49%. Bile acid binding by rice bran may account to a great extent for its cholesterol‐lowering properties, while bile acid binding by oat bran suggests that the primary mechanism of cholesterol lowering by oat bran is not due to the bile acid binding by its soluble fiber. Bile acid binding was not proportional to the soluble fiber content of the cereal brans tested. Except for dehulled barley, bile acid binding for rice bran, oat bran, and β‐glucan enriched barley appear to be related to their IDF content. Highest relative bile acid binding values for rice bran and β‐glucan enriched barley were observed on an equal protein basis, whereas highest values for dehulled barley were based on IDF. Data suggest that of all four cereals tested, bile acid binding may be related to IDF or protein anionic, cationic, physical and chemical structure, composition, metabolites, or their interaction with active binding sites.     

In Vitro Binding of Puroindolines to Wheat Starch Granules

Puroindoline (pin) preparations made from flours of hard and soft wheats contained a mixture of pin‐a, 0.19/0.53 α‐amylase inhibitor, and purothionins. Starch granule preparations from the same cultivars were treated with proteinase to remove surface proteins and incubated with solutions of the pin preparations. Binding of pin‐a and purothionins but not the 0.19/0.53 inhibitor was observed with no apparent differences between the behavior of the pin preparations or starch granule preparations from hard or soft types. No binding was observed when several other proteins (bovine serum albumin, total albumins, a commercial preparation of wheat α‐amylase inhibitors, and barley β‐amylase) were incubated with the starch granules under the same conditions, indicating that in vitro binding can be used to study specific starch granule and protein interactions.     

Effect of Specific Mechanical Energy on Properties of Extruded Protein‐Starch Mixtures

The effect of the specific mechanical energy (SME) during extrusion of a protein‐starch mixture was studied by analyzing the glass transition temperature (T_g) and starch gelatinization. We found that the SME values of 344 to 2108 kJ/kg did not significantly change the T_g of the product. To explain the insensitivity of T_g to SME in spite of reported fragmentation taking place during extrusion, we studied the effect of the molecular weight (MW) on T_g in a model system consisting of dextrans of varying molecular weights. We found that the effect of the molecular weight on the T_g reached a plateau at 6.7 × 10⁴. Because the reported size of the fragments created during the extrusion process is larger than this, we were able to explain the apparent insensitivity of T_g to SME in the protein‐carbohydrate matrix studied. However, we found that starch gelatinization varied with SME, the degree of gelatinization being higher for systems exposed to higher SME.     

Artificial Lignification of Maize Cell Walls Does Not Affect In Vitro Bile Acid Adsorption

Bile acid adsorption by lignified dietary fiber in the human intestine is proposed as a mechanism for lowering blood cholesterol level and reducing colon cancer risk. In this study, we investigated how the concentration and composition of lignin in fiber influences the in vitro adsorption of primary bile acids (glycocholate, taurocholate, and glycochenodeoxycholate) and a secondary bile acid (deoxycholate). Adsorption studies were performed by incubating nonlignified and artificially lignified maize cell walls (dehydrogenation polymer‐cell walls) with bile acids under conditions imitating the small intestine and distal colon. Artificially lignified cell walls had varying but defined lignin concentrations (4.8–19.0%) and compositions (varying from pure guaiacyl to pure syringyl lignins) but a uniform polysaccharide‐protein matrix. Adsorption of bile acids by cell walls was in a range of 6–31% (4–26 nmol of bile acids/mg of cell walls), with glycochenodeoxycholate showing the highest adsorption rates. Neither lignin concentration nor lignin composition influenced bile acid adsorption, thus disproving a major role of lignin in bile acid adsorption.     

Molecular Weight of β‐Glucan Affects Physical Characteristics,In Vitro Bile Acid Binding,and Fermentation of Muffins

Muffins containing different amounts and molecular weights (MW) of β‐glucan were evaluated for the effect of β‐glucan on the physical characteristics of the muffins and on in vitro bile acid binding and fermentation with human fecal flora. Wheat flour muffins were prepared with the addition of β‐glucan extracts with high‐, medium‐, or low‐MW. For oat flour muffins, the native oat flour contained high‐MW β‐glucan; the oat flours were treated to create medium‐ and low‐MW β‐glucan within the prepared muffin treatments. For each 60‐g muffin, the amounts of β‐glucan were 0.52, 0.57, and 0.59 g for high‐, medium‐, and low‐MW β‐glucan wheat flour muffins, and 2.38, 2.18, and 2.23 g for high‐, medium‐, and low‐MW β‐glucan oat flour muffins, respectively. The lower the MW of the β‐glucan in muffins, the lower the height and volume of the muffins. The oat flour muffins were less firm and springy than the wheat flour muffins as measured on a texture analyzer; however, MW had no effect on muffin texture. The oat flour muffins bound more bile acid than did the wheat flour muffins. The muffins with high‐MW β‐glucan bound more bile acid than did those with low‐ and medium‐MW β‐glucan. Muffin treatment affected the formation of gas and total short‐chain fatty acids (SCFA) compared with the blank without substrate during in vitro fermentation. There were no differences in pH changes and total gas production among muffin treatments. The high‐MW β‐glucan wheat flour muffins produced greater amounts of SCFA than did the wheat flour muffin without β‐glucan and the oat flour muffins; however, there were no differences in SCFA production among muffins with different MW. In general, the β‐glucan MW affected the physical qualities of muffins and some potential biological functions in humans.     

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.     

In Vitro Bile‐Acid‐Binding of Whole vs. Pearled Wheat Grain

Health benefits of consuming whole grains are reduced risk of heart disease, stroke, and cancer. The U.S. Health and Human Services and USDA dietary guidelines recommend consumption of 6–10 oz of grain products daily and one‐half of that amount should contain whole grains. Whole grains contain vitamins, minerals, fiber, and phytonutrients. Bile‐acid‐binding capacity has been related to cholesterol lowering potential of food fractions. Lowered recirculating bile acids results in utilization of cholesterol to synthesize bile acid and reduced fat absorption. Secondary bile acids have been associated with increased risk of cancer. Bile‐acid‐binding potential has been related to lowering the risk of heart disease and that of cancer. It has been reported that bile‐acid‐binding of wheat bran is not related to its total dietary fiber (TDF) content. Whole (W) grain as well as pearled (P) hard red winter wheat (Hrw), hard white winter wheat (Hww), and durum wheat (DU) cooked grains were evaluated for in vitro, bile‐acid‐binding relative to cholestryramine (a cholesterol lowering bile‐acid‐binding drug). On dry matter basis (db) relative bile‐acid‐binding values were 7.7% WHrw; 7.5% WHww; 6.3% PHww; 6.0% PHrw; 5.5% WDU; and 5.4% PDU. On a TDF basis, binding values were 42–57% of that for cholestyramine for the whole and pearled wheat grains tested. Bile‐acid‐binding values (db) for WHrw and WHww were similar and significantly higher than those of PHww, PHrw, WDU and PDU. Similar bile‐acid‐binding of WHww to that of WHrw suggest that the red color commonly associated with whole grain may not necessarily indicate more healthful potential. Data suggest that cooked WHrw and WHww wheat have significantly higher health‐promoting potential than pearled grains. WDU or PDU wheat health‐promoting potential was similar to that of PHww or PHrw. Consumption of products containing WHrw and WHww are recommended.     

Bran Size Distribution at Milling and Mechanical and Biochemical Characterization of Common Wheat Grain Outer Layers: A Relationship Assessment

Mechanical properties of wheat grain outer layers from common wheat (Triticum aestivum L.) cultivars known to display distinct milling behavior were analyzed using uniaxial tension tests. Tensile modulus and strain to rupture of the tissues distinguished between the wheat cultivars. Values of strain to rupture were related to coarse bran size generated by grain milling, a characteristic that distinguishes the two hardness classes. As content of an aleurone marker in total or first break flour was also related to coarse bran size, extensibility of wheat grain outer layers' could be a key parameter to explain the observed tissue mechanical behavior and thus distribution of the aleurone layer content in flours. As tissue mechanical properties are generally linked to the cell wall biochemical composition and structure, analysis of the main wheat outer layers' cell wall compounds was undertaken to establish relationships with the differences observed in mechanical properties. No clear correlation could be found with one of the wheat outer layers' component but involvement of the outer layers' cell wall structure in the tissues behavior at milling was confirmed.     

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.     

麦麸纤维素与腐植酸复合保水剂的制备及性能

[目的]研究利用麦麸提取的纤维素与腐植酸共聚制备复合保水剂的方法及其性能,以解决现有保水剂生物难降解,成本高,污染大,再生性能差等问题。[方法]采用碱法从麦麸中提取纤维素,首次与腐植酸、丙烯酸水溶液聚合制备了复合保水剂。用扫描电子显微镜(SEM)、热重分析(TG)分别对树脂的表面形貌、热稳定性进行了表征,考查了NaOH、引发剂、交联剂、麦麸、腐植酸用量对复合保水剂吸水率的影响,并对温度、不同交联剂、再生性能进行了探讨。[结果]麦麸质量0.15g,丙烯酸20ml,交联剂(N,N-亚甲基双丙烯酰胺)的质量是丙烯酸质量的0.03%,引发剂的质量是丙烯酸质量的0.8%,腐植酸0.1g,NaOH浓度80%,温度80℃时,吸水倍率最高,蒸馏水达到了989g/g,对地下水的吸水倍率达到了120.34g/g。对盐水的吸水倍率达到了62.76g/g。[结论]实验方法制备的保水剂再生性能、热稳定性良好,较文献报道的保水剂吸水效果优异,可以在实际生产和生活中推广应用。     

Influence of UV Exposure on Phenolic Acid Content,Mechanical Properties of Bran,and Milling Behavior of Durum Wheat (Triticum Durum Desf.)

Durum wheat bran was exposed to UV radiation up to 48 hr and the changes in ferulic acid (FA) content in the peripheral part s of grain were measured. The treatment resulted in a 25% decrease in FA monomer and a 44% decrease in dehydrodiferulic acid (DHD) ester‐linked to the cell‐wall arabinoxylans. This reduction was partly explained by a significant increase of FA (30%) and DHD (36%) engaged in hot alkali‐labile linkages. The results suggest that UV irradiation induced the formation of new cross‐links between feruloylated arabinoxylan and lignin in the pericarp. The effects of UV treatment on bran mechanical properties and wheat milling behavior were investigated. UV irradiation for 15 hr increased the stress to rupture by 30% and decreased the extensibility of bran tissues by 54%. This stiffening was associated with an increase in bran friability during grinding. Although this effect was due in part to the hydrothermal history of the grain, chemical modification induced by UV significantly influenced the size reduction of bran particles, which can be explained by the modification of the mechanical properties of bran. Relationships between the organization of cell‐wall polymers, the mechanical properties of tissues, and the behavior of wheat grain during milling were investigated.     

鸡肝脏胆汁酸结合蛋白(L-BABP)抗血清制备及组织表达特性分析

制备鸡(Gallus gallus)肝脏胆汁酸结合蛋白(L-BABP)的多克隆抗血清,并分析L-BABP的组织表达特性.利用RT-PCR扩增L-BABP基因的CDS区,构建鸡L-BABP基因的GST融合蛋白表达质粒pGEX-4T/L-BABP.将重组表达质粒转化到大肠杆菌(Escherichia coli)BL21中,经IPTG诱导后产生GST/L-BABP融合蛋白,利用Glutathione Sepharose 4B亲和层析纯化目的蛋白,将纯化的GST/L-BABP融合蛋白免疫家兔制备多克隆抗血清.诱导得到了1个38 kD(12 kDL-BABP+26 kD GST)的融合蛋白,经间接ELISA方法测定制备的抗血清效价为1:100 000.利用此抗血清分析鸡L-BABP的组织表达特性,结果表明该基因仅在肝脏组织中特异性表达,在肾、肺、腿肌、腺胃、胸肌、心脏、脂肪、脾、回肠、肌胃、空肠和十二指肠等12种组织中没有检测到表达信号.本研究制备的高效价、高特异性的鸡L-BABP抗血清,为从蛋白水平上深入研究L-BABP的生物学功能提供了良好的基础.     

In Vitro Effects of Agriculture Pollutants on Microcrustacean and Fish Acid Phosphatases

Chemical inputs from agricultural activities represent a threat to aquatic biota and its biochemical systems. Among these systems, acid phosphatases are involved in autophagic digestive processes, decomposing organic phosphates, signaling pathways, and other metabolic routes. In vitro tests are helpful to generate hypotheses about pollutant mechanisms of action through comparison of the toxicity effects of these compounds. In this work, we investigated the inhibitory effects of four organic pesticides and three metals on the acid phosphatases extracted from the freshwater microcrustacean Daphnia similis and the fish Metynnis argenteus. Our results demonstrated that only the metals have considerable inhibitory effects (50% or higher) on the enzyme activities. The calculated median effect concentrations (IC50) for the enzyme inhibition were 0.139 mM Hg²⁺ (fish enzyme), 0.652 mM Cu²⁺ (fish enzyme), and 1.974 mM Al³⁺ (Daphnia enzyme). Due to the relatively low value of the inhibition parameter for Hg²⁺, its inhibitory property could be used as a tool for Hg²⁺ detection in environmental samples. The enzyme activities obtained in the presence of the inhibitors are potential data as in vivo biomarkers for metals in both aquatic species.     

FT‐Raman Spectra of Unsoaked and NaOH‐Soaked Wheat Kernels,Bran, and Ferulic Acid

The sodium hydroxide (NaOH) test for determining wheat color class depends on the observation that on soaking in NaOH, red wheat turns a darker red and white wheat turns straw yellow. To understand the mechanism of this test, Raman spectra of wheat bran, wheat starch, ferulic acid, and whole kernels of wheat, before and after NaOH soak, were studied. The major observable components in the whole kernel were that of starch, protein, and ferulic acid, perhaps esterified to arabinoxylan and sterols. When kernels are soaked in NaOH, spectral bands due to ferulic acid shift to lower energy and show a slightly reduced intensity that is consistent with deprotonation of the phenolic group and extraction of a portion of the ferulic acid into solution. Other phenolic acids, alkyl resorcinols, and flavonoids observed in the NaOH extracts of wheat by HPLC were not observed in the Raman spectra. Wheat bran accounts for most of the ferulic acid in the whole kernel, as indicated by the increased intensity of the doublet at 1,631 and 1,600 cm^‐1 in the bran. The intense starch band at 480 cm^‐1 in whole kernel wheat was nearly absent in the wheat bran.     

Effect of Specific Mechanical Energy on Protein Bodies and α-Zeins in Corn Flour Extrudates

Zeins, the storage proteins of corn, are located in spherical entities called protein bodies. The disruption of protein bodies and zein release during extrusion may influence the texture of corn-based extruded foods. In this work, chemical and microscopic studies were conducted on corn flour that had been extruded under mild to extreme conditions to determine the specific mechanical energy (SME) required to break apart protein bodies and release α-zein, and to assess changes in protein-protein interactions. Transmission electron microscopy with immunolocalization of α-zein revealed that starch granules and protein bodies remained intact under mild processing conditions (SME 35–40 kJ/kg), but under harsher conditions, protein bodies were disrupted and α-zein was released. At SME ≈100 kJ/kg, protein bodies appeared highly deformed and fused together with the α-zein released, whereas at higher SME, protein bodies were completely disrupted and α-zein was dispersed and may have formed protein fibrils. Protein in extrudates was less soluble in urea and SDS than in unprocessed corn flour, but it was readily extracted with urea, SDS, and 2-ME. This was likely due to protein aggregation upon processing due to a prevalence of hydrophobic interactions and disulfide bonds. This research directly relates SME during extrusion to chemical and structural changes in corn proteins that may affect the texture of corn-based, ready-to-eat food products.     

In Vitro Digestion of RS4‐Type Resistant Wheat and Potato Starches,and Fermentation of Indigestible Fractions

RS4‐type resistant wheat starch (RWS) and resistant potato starch (RPS) were subjected successively to in vitro digestion with pepsin and pancreatin‐bile, and the indigestible residues (82.1% db and 74.1% db, respectively) were recovered and subsequently fermented by in vitro techniques using fresh human fecal microbiota as inoculum. Scanning electron microscopy of the indigestible residues showed surface erosion on the residual granules. Total gas production during the in vitro fermentation increased almost linearly over time with the two resistant starches exhibiting similar gas production rates, as well as a similar rate of production of total short‐chain fatty acids (SCFA). The indigestible fractions from both starches produced acetate as the major SCFA and relatively higher levels of butyrate than propionate, but wheat starch tended to produce more butyrate over time than potato starch. Fractional molar ratios of acetate, propionate, and butyrate from the RWS and RPS were 0.586:0.186:0.228 and 0.577:0.200:0.223, respectively. The calculated caloric contributions of the RWS and RPS are ≈33% lower than for unmodified starch and are comparable to those reported in the literature for RS2 and RS3 high‐amylose maize starches.     

Comparison of In Vitro PBET and Phosphoric Acid Extraction as an Approach to Estimate Selenite and Selenate Bioaccessibility from Soil

Several approaches have been used to estimate the bioaccessibility of trace metals from soils. Here, we applied phosphoric acid extraction and the in vitro test physiologically based extraction (PBET) to soils containing selenium (Se) and compared their performance in estimating the bioaccessibility of Se. For this purpose, we used two soil samples and two Certified Reference Material soil samples with a range of Se concentrations. The total Se contents were measured in the samples and in the extracts by hydride generation–atomic fluorescence spectroscopy. Moreover, we also measured selenite and selenate in the soil extracts (from phosphoric acid and from the PBET) using the coupled techniques liquid chromatography–UV photooxidation–atomic fluorescence spectroscopy and liquid chromatography–mass spectrometry with inductively coupled plasma. From the results obtained in the present study, the PBET showed that the selenium bioaccessible fraction was mainly attributed to the gastrointestinal step. When comparing the results from PBET with those of the phosphoric acid extraction, similar values of Se (IV) and Se (VI) were obtained for both extraction systems. An estimation of the bioaccessibility percentage of Se is also reported.     

In Vivo and In Vitro Inhibitions of Red Drum (Sciaenops ocellatus) Brain Acetylcholinesterase and Liver Carboxylesterase by Monocrotophos at Sublethal Concentrations

The toxic effects of monocrotophos at sublethal concentrations on red drum (Sciaenops ocellatus) brain acetylcholinesterase (AChE, EC 3.1.1.7) and liver carboxylesterase (CaE, EC 3.1.1.1) were examined. After monocrotophos exposure for 4 days at 0.25, 0.5, 1 and 2 mgL^-1 respectively, the AChE activity goes down progressively with the increaseof monocrotophos concentration, and CaE activity reaches the lowest rapidly at the lowest monocrotophos concentration and keeps almost the lowest with the increase of monocrotophos concentration. In time-effect experiments, after exposure to 0.5 mg L^-1 monocrotophos for 1, 2, 4 and 7 days, the activities of two enzymes change in similar trends as found in concentration-effect experiment. The in vivo inhibitions of brain AChE by monocrotophos depend better on concentration and time than CaE. The inhibition of brain AChE by monocrotophos are weaker significantly than that of liver CaE, revealing that CaE may protect AChE in vivo. In addition, half inhibition concentration(IC₅₀) of CaE is significantly lower than AChE(7.2 × 10^-4 mmol L^-1 vs 0.21 mmol L^-1), explaining the protection role of CaE on AChE.