Binding of Zinc to Apple Fiber, Wheat Bran, and Fiber Components

Zinc ion binding to commercial brans, fiber, and fiber components was studied by equilibrium dialysis. Maximum initial concentration of zinc bound by 50 ma of apple fiber (AF) and wheat bran (WB) at pH 7.2 was 220 μg. AF and WB binding capacities were significantly lower for soluble fractions than for unfractionated materials. The water-soluble fraction's binding capacity was 90% lower for AF than for WB. Hemicellulase and phytase slightly increased AF binding capacity but reduced WB capacity. Pectinase increased both AF and WB capacity slightly. Binding capacities of commercially available individual fiber components decreased in the order: lignin > polypectin > pectin > gum > cellulose. Zinc-binding capacities of various dietary fiber types differ, accounting for different zinc bioavailabilties of some foods.     

Untersuchungen an Polysaccharid-, Pektin- und Ballaststoff-Fraktionen von Sanddornbeeren

The alcohol-insoluble substance (AIS) was prepared from freshly picked buckthornton berries (Hippophae rhamnoides L.) (4.70% of the fresh substance). By sequential extraction with water, ammonium oxalate, 0.05 N HC1 and 0.05 N NaOH, the following quantities of galacturonan/ 100 g AIS were obtained: 0.15 g, 0.4 g (ca.), 0.94 g, 2.29 g resp. These pectin extracts were purified as Cu²⁺ salts. After dialysis they were fractionated into a water-soluble and a water-insoluble part. In these fractions Glc, Gal and Xyl were the predominant neutral saccharide units. Ara, Rha and Man were present in smaller amounts. A higher GalA content (in g per 100 original AIS) was found in the soluble fractions (with the exception of the alkali extract). The pectins from buckthornton berries are middle-esterified and partially acetylated. The composition of the AIS was determined as 9.25% pectin, 34.8% protein and 38.9% total polysaccharides. In the residue after sequential pectin extraction (RE), which contained 60.0% of the AIS, 3.89% pectin, 12.9% protein and 28.0% total polysaccharides were found. By the enzymatic method the percentages of soluble and insoluble dietary fiber were estimated as 13.6 % and 34.1% respectively, whereas the RE contained 5.1% soluble and 34.4% insoluble fiber. The following dietary fiber fractions were determined by the detergent method for both preparations: in case of AIS 36.2% NDF, 3.0% NDF filtrate, 28.0% ADF and 9.6% lignin were found to be present, whilst in the RE, the following components were estimated: 32.8% NDF, 1.4% NDF filtrate, 26.1% ADF and 10.1% lignin. The data presented relates to 100 g original AIS. The water binding capacity was observed to decrease from 7.50 g H₂O (AIS) to 4.26 g H₂O (RE) per 1 g original AIS. For both of these preparations, more than 40 % of bound water was found in the NDF fractions and approximately 30% in the ADF fractions.

     

Effects of spontaneous heating on fiber composition, fiber digestibility, and in situ disappearance kinetics of neutral detergent fiber for alfalfa-orchardgrass hays

During 2006 and 2007, forages from 3 individual hay harvests were utilized to assess the effects of spontaneous heating on concentrations of fiber components, 48-h neutral detergent fiber (NDF) digestibility (NDFD), and in situ disappearance kinetics of NDF for large-round bales of mixed alfalfa (Medicago sativa L.) and orchardgrass (Dactylis glomerata L.). Over the 3 harvests, 96 large-round bales were made at preset bale diameters of 0.9, 1.2, or 1.5 m, and at moisture concentrations ranging from 9.3 to 46.6%. Internal bale temperatures were monitored daily during an outdoor storage period, reaching maxima (MAX) of 77.2°C and 1,997 heating degree days >30°C (HDD) for one specific combination of bale moisture, bale diameter, and harvest. Concentrations of all fiber components (NDF, acid detergent fiber, hemicellulose, cellulose, and lignin) increased in response to spontaneous heating during storage. Changes in concentrations of NDF during storage (poststorage - prestorage; ΔNDF) were regressed on HDD using a nonlinear regression model (R² = 0.848) that became asymptotic after ΔNDF increased by 8.6 percentage units. Although the specific regression model varied, changes (poststorage - prestorage) in concentrations of acid detergent fiber, cellulose, and lignin also increased in nonlinear relationships with HDD that exhibited relatively high coefficients of determination (R² = 0.710 to 0.885). Fiber digestibility, as determined by NDFD, was largely unaffected by heating characteristics except within bales incurring the most extreme levels of HDD or MAX. In situ assessment of ruminal NDF disappearance kinetics indicated that disappearance rate (K_d) declined by about 40% within the range of heating incurred over these hay harvests. The change in K_d during storage (ΔK_d) was related closely to both HDD and MAX by nonlinear models exhibiting high R² statistics (0.907 and 0.883, respectively). However, there was no regression relationship between changes (poststorage - prestorage) in effective ruminal disappearance of NDF and spontaneous heating, regardless of which heating measure was used as the independent variable. The close regression relationship between ΔK_d and measures of spontaneous heating indicates clearly that ruminal NDF disappearance was altered negatively by some direct or indirect aspect of spontaneous heating. However, it was equally apparent that these effects were offset by an expanding pool of dry matter recovered as potentially degradable NDF.     

Effect of pH and Heat Treatment on the Binding of Calcium, Magnesium, Zinc, and Iron to Wheat Bran and Fractions of Dietary Fiber

The effect of pH and heat treatment on the binding of added food grade sources of calcium, magnesium, zinc, and iron to a standard wheat bran, cellulose, and lignin was investigated. 1% solutions of pectin and guar gum were examined for their ability to bind these metals in aqueous solution. Lignin and pectin was found to have high metal binding capacities. Metal binding to fiber was found to be pH dependent. Toasting had no effect on metal binding by cellulose, but had a significant effect on the binding of metals by lignin and wheat bran. Boiling had a significant effect on the binding of metals by cellulose, lignin, and wheat bran.     

In Vitro Binding of Vitamin B-6 by Selected Polysaccharides, Lignin, and Wheat Bran

Previous research has suggested that dietary fiber can reduce the bioavailability of certain micronutrients by ionic binding or physical entrapment. In this study, the ability of eight purified polysaccharides, lignin, and wheat bran to bind B-6 vitamers was examined in vitro using equilibrium dialysis under physiological conditions. The polysaccharides used were cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, methyl cellulose, citrus pectin, xanthan gum, sodium alginate, and gum arabic. No significant binding was detected when pectin was dialyzed to equilibrium at, 0.5, 0.75, and 1% levels in the presence of 0.1 or 0.1 mM pyridoxine, pyridoxamine, or pyridoxal. When 1% wheat bran, lignin, and the test polysaccharides were incubated overnight with 0.1 mM pyridoxine prior to dialysis, to allow for any slow binding process to occur, no in vitro binding of pyridoxine by any of the test materials could be observed on equilibrium dialysis. These results are consistent with findings of in vivo experiments which showed that cellulose, pectin, and bran did not significantly decrease the bioavailability of vitamin B-6 when fed to the rat and/or the chick.     

Heavy metal uptake by lignin: comparison of biotic ligand models with an ion-exchange process

Metal uptake by kraft lignin, hereafter referred to as lignin, occurs by displacement of protons or bound metals with equilibrium constants K(ex)H and K(ex), respectively. Values calculated for wide ranges of initial concentrations are reasonably constant, thereby demonstrating the validity of these displacement processes and proving that uptake in these systems is not simple adsorption. It was found that the stoichiometry for Sr and Cd uptake by Ca-loaded lignin is 1 mol of metal for 1 mol of Ca released. This observation for metals of very different binding strengths is difficult to rationalize with the biotic ligand model as generally applied but is in complete agreement with an ion-exchange process. Binding strengths to lignin, which contains only oxygen ligands, follow the order Pb > Cu > Zn > Cd > Ca (strongest to weakest). For proton displacement, only more tightly bound metals such as Pb, Cu, Zn, and Cd can compete with protons for anion-binding sites at low pH, but at high pH, uptake of Ca, Sr, and Li can occur. An observed logarithmic decrease of K(ex)H with pH can be explained by having only weaker acids available for proton displacement under more basic conditions. The advantages and disadvantages of using adsorption and biotic ligand models for an ion-exchange process are discussed.     

KCI, CaCI2, Na+ Binding, and Salt Taste of Gum Systems

Aqueous nonionic (0.3% w/v) and ionic (0.1% and 0.3% w/v) gum systems containing NaCl, or equal weights of NaCl plus KCl, or NaCl plus CaCl, were examined. At equivalent molar concentrations of added ions, ²³Na NMR transverse relaxation rates (R₂, set^?1) showed an increase in average Na⁺ mobility with the addition of K⁺ or Ca²⁺ to ionic gum systems. Correspondingly, salt taste increased with addition of KCl as determined by Decision Boundary modeling of subject identification data. Viscosity did not affect saltiness. Na⁺ was free to induce salt taste when K⁺ was bound to the gum. Enhancement of salt taste by KCl is due, in part, to competitive binding of Na⁺ and K⁺ in a system.     

Analysis of element species fractions in buckwheat and amaranth flours by SEC/ICP-MS and MALDI-MS

Fractionation of Co, Cu, Fe, Mn, Mo, Ni, P and Zn in extracts of buckwheat and amaranth flour in 0.02 mol·l⁻¹ Tris-HCl (pH = 7.5) buffer was performed by SEC/ICP-MS. All metals except for Fe and Mn (both samples) and Cu (amaranth only) are concentrated in a low-molecular fraction (M _r < 2 kDa). Fe is bound in a high-molecular fraction (M _r > 150 kDa). The main part of Mn is present as a labile complex or an ionic form. Cu in amaranth extract is also bound in medium-molecular fractions (10 and 40 kDa) and in a high-molecular one (M _r > 150 kDa). Fractions rich in trace metals were isolated using preparative-scale SEC and the organic ligands of metals were refined by immobilized metal affinity chromatography. Low content of sulphur-containing amino acids (Cys, Met) and high content of acidic amino acids (Glu, Asp) are typical for all these purified fractions. A part of Zn (buckwheat) and almost all Cu (amaranth) in the low-molecular fractions were located in phosphorus rich sub-fractions. However, all Ni (both samples), the majority of Zn (buckwheat) and all Cu (buckwheat) were found in phosphorus-less sub-fractions. No phytochelatins were found in MALDI-MS spectra of isolated ligands.     

Water holding capacity of selected soluble and insoluble dietary fibre

A centnfugation method was developed to determine water holding capacity (WHC) of lignin, cellulose, pectin, whole locust bean gum (LBGW) and insoluble locust bean gum (LBGI) and was compared with the AACC method using cellulose, lignin and LBGI. WHC was found to be highest for LBGW>pectin>LBGI>lignin>cellulose. Solubility and chemical configuration rather than particle size, were the main determinants of WHC. The AACC method tended to overestimate WHC for cellulose, LBGI and lignin.     

Dietary Fiber Binding of Bile Acid through Mineral Supplementation

Iron and/or calcium were added to psyllium, guar gum, locust bean gum, citrus rag, high methoxy pectin, and low methoxy pectin. This mixture was then incubated with either cholic acid, deoxycholic acid, glycocholic acid, or taurocholic acid to evaluate the effect of minerals on fiber-bile acid binding. The addition of iron with or without calcium increased the binding of deoxycholic acid to all fibers (p≤0.01 and p≤0.025) except low methoxy pectin. Iron and calcium caused increased binding of high methoxy pectin to all bile acids (p≤0.01 and p≤0.025). Dietary fiber's ability to bind certain bile acids may be maximized through mineral supplementation.     

Binding of Iron by Cellulose, Lignin, Sodium Phytate and Beta-Glucan, Alone and in Combination, Under Simulated Gastrointestinal pH Conditions

Cellulose (Ce), Lignin (L), Na phytate (P) and beta-glucan (G), alone, and in combination, were evaluated as to their effect on iron profiles in model systems containing FeSO₄• 7H₂O under simulated gastrointestinal pH conditions. Both cellulose and lignin alone, were found to bind a high percentage of the iron in an insoluble form at pH 5.7±0.4 and pH 6.6±0.1, but less at pH 2.0±0.1. However, in the presence of other model components, cellulose unlike lignin had a minimal effect on total binding at all pH levels. Na phytate, alone, formed soluble complexes at all pH levels and when added to lignin led to the solubiization of some of the iron bound to lignin. Beta-glucan formed soluble iron complexes, which appeared to have a low binding strength with iron.     

Cellulose, Hemicellulose and Lignin Content of Raw and Cooked Spanish Vegetables

The content in NDF, ADF, cellulose, hemicellulose, and lignin of 22 raw and 19 cooked vegetables (14 boiled, and 5 fried) widely consumed among the Spanish population was determined according to the method of Van Soest. Cooking generally increases the NDF, ADF and cellulose content on a dry weight basis. Normal size servings of the vegetables were prepared and their NDF, cellulose, hemicellulose and lignin contents calculated. We observed that, with vegetables of common use, a total amount of 15–20 g/day of these fiber components can be obtained; according to current knowledge this implies beneficial physiological effects for a broad human pathology.     

In Vitro Binding of Vitamin E to Selected Dietary Fiber Sources

An in vitro method was used to assess interaction between whole fiber (WF) sources and vitamin E under simulated physiological conditions (pH 2, pH 7, pH 2–7; bile salt 5–15 mM; 37°C). Dose-response and binding characteristics (via Scatchard analysis) were examined. Binding of vitamin E by lupin and gum were higher (p≤0.05) at pH 2 and pH 7 than at the sequential treatment. Oat bran, treated at pH 7 or sequentially, showed increased (p≤0.05) binding of vitamin E as fiber level increased (25 - 100 mg). Scatchard plots revealed two specific noninteracting binding sites for sugarbeet and barley bran. Affinities (K_d) and capacities (n) were compared among fibers. Affinities for vitamin E were: sugarbeet>oat>lupin>barley>gum. Capacities were: barley > gum > lupin > sugarbeet > oat. Vitamin E binding to DF is complex, multifactorial, and not due to a single mechanism.     

Spectrometric determination of iron and copper in vegetable oils after separation with Schiff base impregnated silica gel column: A simple approach for eliminating the high organic matrix

A simple solid‐phase extraction method has been described for the separation of Fe(III) and Cu(II) from liquid vegetable oils using N,N′‐bis(4‐methoxy salicylidene) ethylenediamine impregnated silica gel and the determination of these ions. The experimental parameters that affect the separation/preconcentration of ions were investigated by batch and column methods prior to the determination by flame atomic absorption spectrometry. Fe(III) and Cu(II) ions in 20.0 g portion of oil samples can be quantitatively sorbed and then eluted completely with 5.0 mL of 2.0 mol L^?1 HNO₃. Limits of detection were calculated as 22.8 and 13.9 μg kg^?1 for Fe(III) and Cu(II), respectively. The repetition of the suggested method was checked by finding relative standard deviation for five repeated analyses, which was 1.5% for Fe(III) and 0.1% for Cu(II). Applicability of the method was controlled with spiked and unspiked sunflower, corn, canola, olive, soya and hazelnut oils.     

Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition.

There is a need to standardize the NDF procedure. Procedures have varied because of the use of different amylases in attempts to remove starch interference. The original Bacillus subtilis enzyme Type IIIA (XIA) no longer is available and has been replaced by a less effective enzyme. For fiber work, a new enzyme has received AOAC approval and is rapidly displacing other amylases in analytical work. This enzyme is available from Sigma (Number A3306; Sigma Chemical Co., St. Louis, MO). The original publications for NDF and ADF (43, 53) and the Agricultural Handbook 379 (14) are obsolete and of historical interest only. Up to date procedures should be followed. Triethylene glycol has replaced 2-ethoxyethanol because of reported toxicity. Considerable development in regard to fiber methods has occurred over the past 5 yr because of a redefinition of dietary fiber for man and monogastric animals that includes lignin and all polysaccharides resistant to mammalian digestive enzymes. In addition to NDF, new improved methods for total dietary fiber and nonstarch polysaccharides including pectin and beta-glucans now are available. The latter are also of interest in rumen fermentation. Unlike starch, their fermentations are like that of cellulose but faster and yield no lactic acid. Physical and biological properties of carbohydrate fractions are more important than their intrinsic composition.     

THE EFFECT OF pH ON RAPESEED GLOBULIN (CRUCIFERIN) BINDING TO ANILINONAPHTHALENE-8-SULFONATE

The fluorescence emission intensity from rapeseed globulin (cruciferin) increased in the presence of anilinonaphthalene-8-sulfonate (ANS) at pH 2.0 but not at pH 10. Fluorescence titration studies showed that at pH 7 cruciferin binds 22 (±0.6) moles of ANS per mole of protein with an average dissociation constant (K_d) of 1.9 (±0.1) × 10^?5 M. At pH 2.0 the number of ligand binding sites (n) decreased to 14 (±0.2) moles of ANS bound per mole of cruciferin. However, the ANS binding affinity increased by about five times (K_d= 3.6 (±1.1) × 10^?6 M). The fluorescence emission spectrum maxima (Λ_max) for the cruciferin-ANS complex showed a blue shift at pH 2 when compared to Λ_max values at pH 7–10. These results are consistent with a loss of the quaternary and tertiary structures of cruciferin and the exposure of surface hydrophobic ANS binding sites at low pH. Cruciferin-ANS binding parameters at pH 10 were not significantly different from values at pH 7; n = 22 and K_d= 2.7 (±0.2) × 10^?5 M. Based on these ANS fluorescence measurements cruciferin is stable under alkaline conditions.     

Effects of Fiber Type and Level on Mineral Excretion, Transit Time, and Intestinal Histology

The effects of various fibers on transit time, jejunal histology, and fecal excretion of nitrogen and five trace elements were determined in rats. Cellulose, microcrystalline cellulose, pectin, soy fiber, and wheat bran were fed at l%, 5%, lo%, and 15% dietary levels based on neutral detergent fiber (NDF) analysis. Transit times varied significantly for both fiber type (P < 0.01) and level (P < 0.05). Jejunal histology showed that macrovilli surface area increased with longer exposure to the fiber and with a higher level fed. There was no effect of fiber level on mineral excretion and only a few general trends with regard to effects of fiber type. It is suggested that dietary fiber fractions other than those determined by NDF analysis influence cation exchange of minerals in the gut.     

Effect of calcium on mineral nutrient uptake and growth of tobacco

The aim of this work was to analyse the dynamics of the nutritional state and biomass production in tobacco plants resulting from the application of various calcium levels (Ca1, 1.25 mol m^?3 CaCl₂; Ca2, 2.50 mol m^?3 CaCl₂; Ca3, 5 mol m^?3 CaCl₂) in the culture medium. Tobacco plants were grown under controlled conditions and submitted to regular fertilisation with macro‐ and micronutrients. The concentrations of Ca, organic N, P, K, Na, Mg, Fe, Mn, Zn, Cu, Cl and B were determined in the roots and leaves. As expected, Ca accumulated progressively with increasing concentration of this element in the culture medium. There was a slight rise in the concentration of organic N but hardly any change in the concentrations of K and Na. In contrast, increasing Ca application caused a gradual decline in P and Mg concentrations. In terms of micronutrient concentrations, Fe, Mn, Zn, Cl and B were influenced positively by Ca treatment. A noteworthy synergetic relationship was found between Ca and B. In contrast, the Cu concentration in the roots declined significantly with increasing Ca application. The effect of Ca on biomass production depended on the organ analysed, since the dry matter content diminished in the roots but was augmented slightly in the leaves. © 2001 Society of Chemical Industry     

Measurement of rumen dry matter and neutral detergent fiber degradability of feeds by Fourier-transform infrared spectroscopy

This study explored the potential of partial least squares (PLS) and Fourier-transform infrared spectroscopy (FTIR) to predict rumen dry matter (DM) and neutral detergent fiber (NDF) degradation parameters of a wide range of feeds for ruminants, as an alternative to the in situ method. In total, 663 samples comprising 80 different feed types were analyzed. In situ DM and NDF degradabilities were determined as follows: effective degradability (ED), rumen soluble fraction (A), degradable but not soluble fraction (B), rate of degradation of the B fraction (C), and indigestible NDF (iNDF). Infrared spectra of dry samples were collected by attenuated total reflectance from 600 to 4000 cm⁻¹. Feeds were randomly classified into 2 subsets of samples with representation of all feed types; one subset was used to develop regression models using partial least squares, and the second subset was used to conduct an external validation of the models. This study indicated that universal models containing all feed types and specific models containing concentrate feeds could provide only a relatively poor estimation of in situ DM degradation parameters because of compositional heterogeneity. More research, such as a particle size distribution analysis, is required to determine whether this lack of accuracy was due to limitations of the FTIR approach, or simply due to methodological error associated with the in situ method. This latter hypothesis may explain the low accuracy observed in the prediction of degradation rates if there was physical leakage of fine particles from the mesh bags used during in situ studies. In contrast, much better predictions were obtained when models were developed for forage feeds alone. Models for forages led to accurate predictions of DM_A, DM_B, NDF_ED, and NDF concentration (R² = 0.91, 0.89, 0.85, and 0.79, standard error = 4.34, 5.97, 4.59, and 4.41% of DM, respectively), and could be used for screening of DM_ED, NDF_C, and iNDF. These models relied on certain regions of the FTIR spectrum (900–1150 and 1500–1700 cm⁻¹), which are mainly compatible with absorption of plant cell wall components, such as cellulose, pectin, lignin, cutin, and suberin, but also with nonstructural carbohydrates and certain active compounds. In conclusion, FTIR spectroscopy could be considered a low-cost alternative to in situ measurements in feed evaluation.     

Rheological properties of gluten-free bread formulations

In this study, the rheological properties of rice bread dough containing different gums with or without emulsifiers were determined. In addition, the quality of rice breads (volume, firmness and sensory analysis) was evaluated. Different gums (xanthan gum, guar gum, locust bean gum (LBG), hydroxyl propyl methyl cellulose (HPMC), pectin, xanthan–guar, and xanthan–LBG blend) and emulsifiers (Purawave^™ and DATEM) were used to find the best formulation for gluten-free breads. Rice dough and wheat dough containing no gum and emulsifier were used as control formulations. The rice dough containing different gums with or without emulsifiers at 25 °C showed shear-thinning behavior with a flow behavior index (n) ranging from 0.33–0.68 (except pectin containing samples) and consistency index (K) ranging from 2.75–61.7 Pa sⁿ. The highest elastic (G′) and loss (G″) module were obtained for rice dough samples containing xanthan gum, xanthan–guar and xanthan–LBG blend with DATEM. When Purawave^™ was used as an emulsifier, dough samples had relatively smaller consistency index and viscoelastic moduli values compared to DATEM. The viscoelastic parameters of rice dough were found to be related to bread firmness. Addition of DATEM improved bread quality in terms of specific volume and sensory values.