Mineral Binding Characteristics of Lignin, Guar Gum, Cellulose, Pectin and Neutral Detergent Fiber under Simulated Duodenal pH Conditions

Effective stability constants (K_cff) and amount of Fe bound by lignin, cellulose, guar gum, low and high methoxy pectin and NDF were determined under simulated duodenal pH conditions. Guar gum bound 8.4 μmol Fe per g fiber with the greatest affinity (K_cff= 6.27 × 10⁶) of any of the fibers studied; NDF, high methoxy pectin, and one of the binding sites of lignin bound 5.0. 5.0, and 19.5 μmol Fe, respectively. per g fiber, with a K_cff > 10⁵, and cellulose bound Fe so weakly that an effective stability constant could not be calculated. Lignin had two distinct binding sites for Fe, Zn, and Cu with the high affinity sites binding in the following order: Fe > Cu > Zn, but with twice as much Cu bound as either Fe or Zn.     

Binding of mineral elements by some dietary fibre components—in vitro (I)

The binding of copper, cadmium and zinc ions to some soluble and gelforming types of dietary fibre (guar gum, low and high methoxylated pectin and sterculia gum) has been investigated potentiometrically. Considerable binding was found to low methoxylated pectin, but the binding to sterculia gum and high methoxylated pectin was less pronounced. The binding to guar gum was negligible. Thus, the formation of complexes seemed to be due to the proportion of free carboxyl groups. The amount of added metal bound to sterculia gum was proportional to the fibre concentration, whereas the pectins showed increased binding at higher fibre concentrations. This was possibly due to intermolecular interactions between the polymers and metal ions. The order of complex formation ability to the fibres investigated was different for different metals. To low methoxylated pectin the order Cu>Zn ⪢ Cd was observed.     

Effect of pH on the in vitro interactions between bile acids and pectin

 The interactions between pectin and bile acids (BA) were investigated after in vitro incubation at 37°C in the pH range of 5.0 – 8.0, separation of the non-absorbed BA using membrane filtration and their estimation by HPLC and HPTLC. In general, the interactions increased with the degree of esterification and the molecular weight (viscosity) of the pectin. They were reduced if the carboxyl groups in the polysaccharide molecules are arranged in a blockwise manner and in the presence of Ca²⁺. The highest interactions were found for unconjugated BA, followed by the corresponding glycine-conjugates. Taurine-conjugates showed the lowest interaction with pectin. Chenodeoxycholic acid and deoxycholic acid reacted more effectively than the trihydroxy bile acid cholic acid in the in vitro experiments. The results show that structural parameters of both BA and pectin play an important role in the extent of their interaction. Received: 28 November 1996 / Revised version: 20 January 1997     

Effect of pH on the in vitro interactions between bile acids and pectin

 The interactions between pectin and bile acids (BA) were investigated after in vitro incubation at 37°C in the pH range of 5.0 – 8.0, separation of the non-absorbed BA using membrane filtration and their estimation by HPLC and HPTLC. In general, the interactions increased with the degree of esterification and the molecular weight (viscosity) of the pectin. They were reduced if the carboxyl groups in the polysaccharide molecules are arranged in a blockwise manner and in the presence of Ca²⁺. The highest interactions were found for unconjugated BA, followed by the corresponding glycine-conjugates. Taurine-conjugates showed the lowest interaction with pectin. Chenodeoxycholic acid and deoxycholic acid reacted more effectively than the trihydroxy bile acid cholic acid in the in vitro experiments. The results show that structural parameters of both BA and pectin play an important role in the extent of their interaction. Received: 28 November 1996 / Revised version: 20 January 1997     

Dialyzable Calcium from Milk Processed with Soluble Fiber-Containing Gums, Thickeners, and Cocoa

Dialyzable calcium form 10% nonfat dry milk (NFDM) processed with gums, thickeners, and cocoa was determined following in vitro peptic-pancreatic digestion. Acidification to pH 4.2, heat pasteurization, or boiling for 30 min did not affect the % dialyzable calcium from 10% NFDM alone or in the presence of any of the additives tested. At a level of 1%, carrageenan, gum arabic, gum karaya, and low-methoxyl pectin significantly decreased (p < 0.05) and agar increased (p < 0.01) % dialyzable calcium. Other gums and thickeners were without effect and viscosity of the food system did not correlate with % dialyzable calcium. Five percent Dutch or natural process cocoa caused a one-third reduction in dialyzable calcium and 1% Dutch cocoa also produced a significant decrease.     

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.     

Viscoelasticity of oxidized starch/low methoxy pectin mixtures in the presence of glucose syrup

The structural properties of mixtures of pectin, oxidized starch and glucose syrup were investigated using small deformation dynamic oscillation. In the absence of added calcium, preparations of low methoxy pectin with glucose syrup formed viscous solutions, which remained crystal-free at subzero temperatures. Samples of oxidized starch and glucose syrup, on the other hand, exhibited solid-like behaviour because of the crystalline nature of the amylose-like helices. Mixtures of the two polysaccharides with the co-solute clearly showed phase inversion from liquid to solid-like behaviour with increasing amounts of starch in the formulation. The transformation was reflected in the textural properties of samples, which varied from thick solutions to firm gels. The viscoelasticity of the system was modified further by the introduction of high methoxy pectin. Preparations of high methoxy pectin and glucose syrup formed rubbery gels whose amorphous nature underwent a glass transition during cooling.     

How Do Xanthan and Hydroxypropyl Methylcellulose Individually Affect the Physicochemical Properties in a Model Gluten‐Free Dough?

To better understand the physicochemical changes imparted by hydrocolloids on gluten-free dough, 2 hydroxypropyl methylcelluloses (HPMCs) and xanthan gum were added at 2%, 3%, and 5% to rice cassava dough without the addition of alternative proteins. The formulated doughs were analyzed using thermoanalytic and rheological techniques to determine the role of water and subsequent flow behavior upon hydrocolloid addition. The baked loaves were then measured for specific loaf volume and tensile strength to determine bread quality. Thermogravimetric analysis (TGA) results revealed that hydrocolloid-added dough held water more tightly than the rice cassava control with an additional water distribution at 85 to 88 °C. Rheologically, the increase of elastic moduli in the low methoxy HPMC and xanthan-added dough became more pronounced with gum addition; however, both HPMC formulations had increased viscous moduli allowing the gas cells to expand without collapsing. In the bread, the final specific loaf volume increased with high methoxy HPMC (2% to 5%) and low methoxy HPMC (2%) but was depressed with increased addition of low methoxy HPMC (5%) and xanthan (3% and 5%). Crumb hardness was decreased in high methoxy HPMC loaves but was increased significantly in low methoxy HPMC (5%) and xanthan (5%) formulations. From the gums studied, it was concluded that high methoxy HPMC was the optimum hydrocolloid in the rice cassava gluten-free dough. PRACTICAL APPLICATION: Two types of hydrocolloids, xanthan gum and HPMC, were individually added to a gluten-free rice cassava formulation. Based on the thermoanalytic and rheological studies on dough, as well as the bread quality studies, high methoxy HPMC at 5% addition was determined to optimally improve the bread quality when only gum addition was considered. This study indicates the potential use of high methoxy HPMC as an additive in gluten-free bread formulations prior to considering alternative proteins.     

In vitro binding of bile acids and triglycerides by selected chitosan preparations and their physico-chemical properties

The selected 11 chitosan samples were evaluated for their fat- and bile acid-binding capacities, physico-chemical properties, and the correlations between each binding capacity and individual physico-chemical properties. The bile acid- and fat-binding capacities were estimated using in vitro assays, whereas the measured physico-chemical properties were deacetylation degree, swelling capacity, and solution viscosity. Chitosan samples might differ in their binding capacities against fat and/or individual bile acids. The bile acid-binding capacities were 0.20-0.61, 0.43-1.63, and 0.61-1.61 μmol/g chitosan for cholic, deoxycholic, and chenodeoxycholic acids, respectively. Stronger binding capacity of chitosan against a selected bile acid does not warrant greater binding capacity for other bile acid. The fat-binding capacity ranged from 1077-1239 g oil/g for the chitosan samples under the experimental conditions. No correlation was observed between any binding ability and individual physico-chemical properties, although the swelling capacity of chitosan was correlated to the solution viscosity (r=0.82, P=0.02) and deacetylation degree (r=-0.62, P=0.04), indicating that none of the measured physico-chemical properties can be used to predict the fat- or bile acid-binding ability of chitosan.     

Volatilities of Short-Chain Fatty Acids in a Fermented Milk Model System as Affected by Stabilizers

A fermented milk model system was employed to investigate the volatilities of butyric, caprylic, and caproic acids as affected by low, intermediate, and high levels of carrageenan, guar and xanthan gums. Carrageenan exhibited no effect on fatty acid volatility. Intermediate levels of guargum increased the volatility of caprylic acid. Low and high levels of guar gum had no effect on free fatty acid volatility. At low and high levels, xanthan gum had no effect on volatilities of fatty acids. The intermediate level of xanthan gum increased volatilities of caproic and caprylic acids. The effects of viscosity were potentiated with increased fatty acid chain length.     

Preparation of Alkyl Esters of Pectin and Pectic Acid

Alkyl esters of pectin and pectic acid have been prepared via three different synthetic routes. Enhancements of intrinsic viscosity, binding to bile acids and to isolated soy protein were shown for these novel pectin derivatives. The development of new and improved pectin-containing products may be enhanced by the ease of preparation and improved functionality of such compounds.     

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.     

Replacement of traditional emulsifying salts by selected hydrocolloids in processed cheese production

Different hydrocolloids were examined as possible replacements for traditional phosphate- and citrate-based emulsifying salts in processed cheese production. The following hydrocolloids (at concentrations in the final product of ≤1.0%, w/w) were chosen: modified starch (with bound sodium octenyl succinate), low methoxyl pectin (alone or combined with lecithin), locust bean gum, κ-carrageenan and ι-carrageenan. The products were assessed by sensory analysis, microscopic image analysis and dynamic oscillatory rheometry. Modified starch, locust bean gum and low methoxyl pectin could not be recommended as replacements for traditional emulsifying salts. Model processed cheeses without traditional emulsifying salts of 40% (w/w) dry matter and 55% (w/w) fat-in-dry matter containing 1.0% (w/w) κ-carrageenan or ι-carrageenan were found to be homogeneous, however the products were hard with fracturable texture.     

CALCIUM, PHOSPHOROUS AND NITROGENOUS COMPOUND CONTENTS OF CHICKEN BROTH FROM BROILER BREAST FRAMES AS AFFECTED BY VARIOUS ACIDULANTS

The effect of acidulants on the total nitrogen, pH, gelatin, calcium, and phosphorous contents of chicken broth was investigated. Acidulants used included: ascorbic, acetic, citric, lactic, and phosphoric acids. All acidulants at a 0.50% level increased (P<0.05) the calcium and phosphorous contents of the broth prepared from broiler breast frames. The highest calcium and phosphorous contents were produced in chicken broths prepared with 0.50% phosphoric acid, followed by citric, lactic, acetic and ascorbic acids. Phosphoric acid-treated broth showed the highest nitrogen and gelatin contents, followed by lactic, citric, acetic, and ascorbic acids, in that order. As phosphoric acid concentration increased from 0 to 0.05%, the total nitrogen and gelatin contents of the broth decreased. However, phosphoric acid, at a concentration as low as 0.025%, increased (P<0.05) calcium and phosphorous extraction. Results indicated that acidulants could be used for the processing of high calcium and phosphorous chicken broth from broiler breast frames.     

Isolation and Characterization of Pectin in Sugar-Beet Pulp

Pectin was extracted from sugar-beet pulp by various solvent fractionation procedures. An optimal HCI-extraction method yielded 19.53% pectin from the raw material. The HCl-isolated pectin contained 81.8% galacturonic acid. The sugar-beet pulp pectin obtained from different extraction procedures had a high methoxy content ( 60% degree of methylation). The pectin also contained 10 to 17.5% neutral sugars which were mainly arabinose and galactose as analyzed by gas chromatography. The peak molecular weights (relative to dextrans) of the pectins as determined by gel permeation ranged from 35,500 to 44,700 daltons. The pectin possessed high water-holding capacity and low viscosity.     

十二种常见亲水胶体对馒头品质影响的研究

本文研究了12种亲水胶体不同添加量(0.2%、0.6%、1.0%)对馒头质构、比容、水分含量及持水力的影响。结果表明:适宜浓度的瓜尔豆胶,高甲氧基柑橘果胶在降低馒头硬度及咀嚼性的同时提高了馒头弹性(p<0.05),总体上有效地改善了馒头的质构特性。0.2%的瓜尔豆胶及魔芋胶,0.2%~1.0%的高甲氧基柑橘果胶、阿拉伯胶及乳清水解蛋白,0.6%~1.0%的低甲氧基柑橘果胶及酪蛋白钠使馒头比容显著增加(p<0.05)。在室温及-4 ℃条件下,与空白比较,除阿拉伯胶对馒头持水力无显著影响外,其他亲水胶体均能不同程度的提高显著馒头的持水力。由此可知,添加适宜浓度的瓜尔豆胶、高甲氧基柑橘果胶对馒头综合品质具有较好的改良效果。     

ADSORPTION of BILE ACIDS ON CEREAL TYPE FOOD FIBERS

A study involving measurement and analysis of adsorption of common bile acids, namely cholic, deoxycholic, and lithocholic acids, on cereal type dietary fibers was conducted. the selected food fibers were oat fiber, rice fiber, barley fiber, corn bran, and wheat bran, which are all extensively used in processed foods. the adsorption data were measured at 37C and 25C, which correspond to approximate human body and room temperatures. Influence of particle size reduction, due to grinding, on a fiber's bile acid binding capacity was examined by using macro size (35–60 mesh) and micro size (100–300 mesh) fibers as adsorbents. the investigation also included the effects of medium pH and the chemical composition. the experimental data were correlated with the Langmuir and the Freundlich isotherms in order to utilize the data in future predictions and simulations.
It was found that the particle size reduction, accompanied by surface area increase, has a significant influence on the adsorption capacity of the fiber. Macro size fibers adsorbed the same bile acid with the following trend: oat > barley > rice > wheat > corn; while micro size fibers followed a somewhat different trend: rice > barley > oat > wheat > corn. This was due to the surface area change after grinding, and a positive correlation between the surface area and the adsorption capacity was observed in each case. the adsorption was favored by acid pH surroundings, and it was positively correlated with the hydrophobicity of the bile acid. were adsorbed on the same fiber with the following trend: lithocholic acid > deoxycholic acid > cholic acid. Fibers adsorbed more bile acid at 25C than they did at 37C. However, the increase in the uptake capacities were not very signipcant.     

膳食纤维对大鼠钙平衡及骨生物力学性能的影响

目的：研究不同结构的膳食纤维对钙平衡及生物力学性能的影响。方法：以大鼠作为动物模型分组饲养,分别饲喂含有50 g/kg麦麸、纤维素、木聚糖、果胶、菊粉、魔芋胶及其混合物的饲料。利用原子吸收光谱法检测饲料、粪便、尿样、股骨中钙含量;利用电解质分析仪测定血清中的总钙、游离钙、结合钙浓度;用三点弯曲法检测股骨的最大载荷。比较摄入不同膳食纤维大鼠钙吸收、血钙水平、尿钙流失、钙保留率、骨钙含量、骨的生物力学性能等参数的差异。结果：在钙吸收率方面,麦麸、纤维素组高于木聚糖、果胶、菊粉、魔芋组,其中木聚糖和魔芋组与麦麸组具有极显著差异（P<0.01）;在尿钙日排出量方面,木聚糖和纤维素组低于其余各组;在钙保留率方面,果胶组最低,处于负钙平衡;在血清钙水平方面,麦麸组血清游离钙浓度和其余实验组没有显著性差异（P>0.05）,但麦麸组结合钙和总钙浓度均高于其他各组;在骨钙含量和骨生物力学性能方面,果胶组明显低于其他各组,木聚糖组的骨最大载荷高于其他各组。结论：麦麸和纤维素等低发酵型膳食纤维的肠道钙吸收率高于木聚糖、果胶、菊粉、魔芋等高发酵型膳食纤维;木聚糖有助于提高大鼠骨生物力学性能;不同膳...     

Effects of dietary broccoli fibre and corn oil on serum lipids, faecal bile acid excretion and hepatic gene expression in rats

To determine the effects of broccoli fibre and corn oil on lipid metabolism, male Sprague-Dawley rats were fed diets containing high (30%) or low (5%) corn oil, in combination with either 7.5% broccoli fibre or cellulose, for 4 months. High corn oil groups had significantly lower serum cholesterol and triglycerides than had low corn oil groups (p < 0.001). Broccoli fibre also lowered serum cholesterol and triglyceride levels compared to cellulose fibre. Faecal bile acid concentrations were higher in high corn oil-fed rats than in low corn oil-fed rats, with broccoli fibre inclusion in high corn oil diets resulting in higher faecal bile acid concentrations. Regardless of corn oil level, broccoli fibre supplementation in the diet resulted in an increase (p = 0.018) in hepatic cytochrome P450, family 7A1 (CYP7A1) expression. High corn oil feeding resulted in reduced expression of fatty acid synthase (FAS) and increased expression of carnitine palmitoyl transferase 1a (CPT1a) and 3-hydroxy-3-methyl-coenzyme A reductase (HMGCR) (p < 0.05). Our findings suggest that high dietary corn oil and broccoli fibre have beneficial effects on lipid metabolism. Corn oil lipid-lowering effects may be due to alteration of hepatic expression of genes involved in lipid synthesis and increased rate of cholesterol catabolism to bile acids. Broccoli fibre may also act via its physical properties to reduce enterohepatic bile acid recycling and intestinal lipid absorption, and increase luminal binding of bile acids, resulting in increased faecal bile acid excretion.     

Role of calcium and calcium-binding agents on the lipase digestibility of emulsified lipids using an in vitro digestion model

Controlling the digestibility of lipids within the gastrointestinal tract is important for developing food and pharmaceutical products. In vitro digestion methods are commonly used to study the influence of formulation composition and microstructure on lipid digestibility. In this paper, we focus on the impact of calcium and calcium-binding agents on the rate of lipid droplet digestion in corn oil-in-water emulsions monitored using a pH-stat method. The rate of fatty acid production increased with increasing calcium, e.g., the free fatty acids released after 20 min digestion was <12% for 0 mM CaCl2, but >95% for 20 mM CaCl2. The ability of calcium to increase the digestion rate was found for three different emulsifiers used to stabilize the initial lipid droplets: lyso-lecithin, caseinate and β-lactoglobulin. For these three systems, the initial rate of lipid digestion increased in the following order lyso-lecithin > β-lactoglobulin > caseinate at both 0 and 20 mM CaCl2, but the rate was considerably faster at higher calcium levels for all systems. The addition of EDTA, a calcium chelating agent, to emulsions containing 20 mM CaCl2 caused an appreciable decrease in lipid digestion rate, reducing the amount of free fatty acids produced after 20 min from around 97% to 32% when the EDTA level was increased from 0 to 5 mM. Finally, we examined the impact of two anionic polysaccharides (pectin and alginate) on the rate of lipid digestion in emulsions containing 20 mM CaCl2. High methoxy pectin, which does not bind calcium strongly, did not have a major effect on the rate of digestion, whereas alginate, which does bind calcium strongly, depressed the rate considerably. This study has important implications for designing and testing delivery systems that control lipid digestion.