Pectin stabilization of soy protein isolates at low pH

The stabilizing behaviour of pectins in acidified dispersions of soy protein was studied. Objective of this work was to understand if different soy isolates and different pectins show differences in stability. The behaviour of a commercially available isolated soy protein (ISP) was compared to that of a soy protein in the laboratory. At pH 3.8 while suspensions of commercial ISP showed significant precipitation, the native SPI (prepared in the laboratory) was much more stable against precipitation. High methoxyl pectin (HMP) had better stabilization behaviour than low methoxyl pectin (LMP). A higher amount of HMP was needed to avoid protein precipitation of native SPI, compared to that used for commercial ISP. It was demonstrated that at low pH pectin forms soluble complexes with SPI through electrostatic interactions.     

酰胺化果胶的特性、应用及研究现状

本文将酰胺化果胶与普通低酯果胶以及高酯果胶进行了多方面的比较，重点介绍酰胺化果胶的特性。结合国内外对酰胺化果胶生产和研究的状况，及其在食品工业和医疗方面的应用现状，对酰胺化果胶生产的开发前景进行了分析。     

A light scattering study on the effects of pH on pectin aggregation in aqueous solution

Light-scattering measurements were carried out on pectins in aqueous solutions of pH ranging from about 4 to 2. The following pectin samples were used: three low methoxyl pectins which were demethylated by ammonia, acid and enzyme (all with a nearly similar methoxyl content from 6.1 to 6.2%), and pectin-NF with 12.04% methoxyl groups and sodium poly-galacturonic acid. When the pH of a 0.05% pectin solution containing 0.1 M NaCl was brought to pH 2 by adding HCl, the mol. wt and radius of gyration increased markedly, thus indicating that pectin molecules aggregate when the pH is lowered.     

酰胺化果胶最佳胶凝条件的探讨

以商品高酯果胶为原料,制备酰胺化果胶,以胶凝破碎强度为检测指标,得到酰胺化果胶的最佳胶凝条件.以pH值、酰胺化果胶浓度、蔗糖浓度、Ca2+浓度4因素为因素,以去离子水配制溶液,保存温度5℃、保存时间48h进行正交试验得到的最佳胶凝条件为:pH值3.6、酰胺化果胶浓度1.4%、蔗糖浓度30%、Ca2+浓度50 mgCa2+/g酰胺化果胶.     

The stabilizing behaviour of soybean soluble polysaccharide and pectin in acidified milk beverages

The mechanisms of stabilization of soybean soluble polysaccharide (SSPS) and high methoxyl pectin (HMP) in acidified milk drinks were studied focusing on the differences in behaviour between the two polysaccharides. The changes in casein micelles size during acidification with glucono-δ-lactone or by direct acidification were measured using light scattering. When HMP was added to skim milk before acidification, pectin adsorbed on the surface of the casein micelles via electrostatic interactions and prevented casein aggregation. Results suggested that adsorption of pectin occurred from the beginning of acidification and somewhat affected the rearrangement of casein micelles in the pH range between 5.8 and 5.0. On the other hand, SSPS, at concentrations up to 2% (w/w), did not interact with caseins at pH >4.6. At pH <4.2 SSPS showed better stabilizing properties than HMP. In addition, between pH 4.2 and 3.2, SSPS-stabilized acid dispersions were not affected by pH, while dispersions homogenized with pectin showed a size distribution that depended on pH. The differences in structure between SSPS and HMP account for the unique functionalities of the two polysaccharides in acid milk systems.     

Wheat Varietal Flours: Influence of Pectin and DATEM on Dough and Bread Quality

The effect of two additives, high methoxyl pectin (P) and the emulsifier diacetyl tartaric acid esters of monoglycerides commonly named DATEM (D) and their mixture (P+D) on dough properties and baking performance of two varietal Argentinean wheat flours (‘Buck Pronto’ [BP]; ‘Klein Escudo’ [KE] was analyzed. Rheological characterization of dough (alveogram, farinograms, texture profile analysis-TPA, and rheometric assays), with and without additives, was performed. SEM was used to evaluate the microstructure of dough. Baking performance was analysed by bread volume measurements, shape ratio of loaves (width/height), and the hardness of crumb and crust. Assays on dough showed differences in alveographic force (W) and in most of the texture profile analysis parameters. Assays on bread showed that BP specific volume was improved with the addition of P and P+D, but shape ratio was only improved with the mixture of P+D. Breads from KE flour with additives presented, in all cases, showed higher volumes and a better shape ratio than those obtained with the control sample. Hardness of KE crumb was diminished by all additives but BP crumb was softened only with the addition of P and P+D. All sensory parameters were improved for both types of bread, particularly with D and P+D.     

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.     

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。     

Stability of pectins during storage

Low methoxyl pectins (LMP) prepared by HCl, NaOH and NH₃ deesterification procedures were stored with or without adding Na₂CO₃ as buffer at room temperature (25–30°C) or exposed to different relative humidities (r.h.) at 37°C. Losses of methoxyl, molecular weight and gelling power were observed in all the pectin samples. During storage, NaOH and NH₃ deesterified LMP were more stable than HCl deesterified LMP with respect to gelling power. The monolayer values ( V _m) of 0.5 to 0.7 g per 100 g of LMP showed that even when stored at 11% r.h., the moisture in LMP was present in the multilayer region which was conducive to methoxyl loss.
NH₃ deesterified LMP precipitated at pH 0.5 and 1.5 after saponification, formed good gels similar to the LMP precipitated at pH 0.5, dried and mixed with buffer. NH₃ deesterified LMP precipitated at pH 3.0 and 4.5, on the contrary, formed only coagulated gels.
The loss of gelling power of LMP during storage was due to depolymerization besides gradual transformation of increasing portions of pectinic acid molecules into pectic acid molecules. High methoxyl pectins with or without added sodium carbonate or citrate as buffer stored at 62 and 75% r.h. showed methoxyl loss. Between r.h. of < 0.1 and 49%, methoxyl loss was more in the buffered samples than in the control.     

Exploring the interactions between blackcurrant polyphenols, pectin and wheat biopolymers in model breads; a FTIR and HPLC investigation

This study explores the interactions between added blackcurrant polyphenols (PPs) and pectin, as well as different bread components in model bread systems. A series of model breads containing flour, yeast, sugar, salt, oil and water, with/without added pectin and blackcurrant PP extract, were prepared and characterised. Results show that adding PPs in addition to pectin increased the total extractable PP content and antioxidant activity of the breads, and decreased the proportion of unextractable high molecular weight proteins (detected by size exclusion-HPLC). The composition of bread formulations influences the amount of anthocyanins, especially delphinidin-3-o-glucoside and delphinidin-3-o-rutinoside, which are retained after bread baking. Replacing flour with starch and gluten, adding blackcurrant PP extract and pectin, or removing bread components (oil, salt or the mixture of yeast and sugar), caused changes in the bread gluten conformations related to Amide I and II bands (revealed by FTIR), as well as the extractability of PPs and proteins (revealed by HPLC).     

百香果皮果胶提取工艺及其对面团和面包品质的影响

从百香果皮中提取果胶作为面包改良剂,以未添加改良剂和添加豆渣的面团为对比,通过质构仪分析百香果皮果胶对生面团延展性和面包坚韧性的影响。结果显示:百香果皮果胶提取的最佳工艺条件为:质量分数为0.45%的草酸铵、料液比1∶45(g/mL)、50 W超声波辅助提取90 min,果胶提取率为24.79%。质构测试结果表明:添加百香果皮果胶的面团拉丝长度、弹性、粘性和内聚性较大,而硬度较小,其面团品质最好。添加豆渣和百香果皮果胶均使面包的硬度和咀嚼性降低,有效改善面包的质构特性。Kramer感官评定结果表明百香果皮果胶面包最受消费者喜爱。     

Effects of added fruit polyphenols and pectin on the properties of finished breads revealed by HPLC/LC-MS and Size-Exclusion HPLC

The positive roles of fruit polyphenols (PPs) and dietary fibres (DFs) in promoting human health and well-being are now well recognised. This study investigates the effects of added fruit PPs and pectin on the composition and extractability of PPs and proteins from finished breads, and complements our recently published papers that focus on the rheological and physicochemical properties of breads containing added PPs and pectin. Breads were prepared in the absence or presence of a high methoxyl (HM) apple pectin and kiwifruit, blackcurrant or apple PP extract, and subjected to texture measurements (crumb firmness), informal sensory evaluations and chemical analyses. An epicatechin standard was also used in place of the fruit PP extract to estimate the extractability and recovery of PPs from bread. Results show that adding a PP extract and pectin to bread modified bread firmness, specific volume, recovery of added PPs, amount of free thiol groups of bread proteins, and also the extractability of PPs and proteins from bread. The recovery of added PPs was the lowest for the APE + HM pectin bread which had the highest bread firmness. High performance liquid chromatography (HPLC)-mass spectrometry (MS) PP profiling revealed that baking caused oxidation of some added PPs such as quercetin and myricetin. Size-Exclusion HPLC analysis showed that adding a combination of PP extract and HM pectin decreased the S–H group concentration and increased the percentage of the Unextractable High Molecular Weight (UHMW) proteins, compared to the control bread. The added pectin and PPs, and possibly the oxidation products of the added PPs, affected the interactions between water and bread components (such as gluten proteins) during dough development and bread baking, causing differences in bread cross-linking microstructure and textural properties, which ultimately influenced the extractability and/or stability of added PPs.     

Effects of trypsin‐hydrolyzed wheat gluten peptide on wheat flour dough

BACKGROUND: Gluten peptide was prepared by trypsin hydrolysis and characterized by high‐performance liquid chromatographic analysis. The effects on non‐frozen and frozen doughs of trypsin‐hydrolyzed gluten peptide (THGP) and its combination with ascorbic acid or KBrO₃ were investigated. RESULTS: Molecular analysis of THGP showed a decrease in the high‐molecular‐weight and an increase in the low‐molecular‐weight sodium dodecyl sulfate‐soluble fractions, compared with those of control wheat gluten. The addition of 8% THGP decreased the mixing time and tolerance of the dough, both with and without ascorbic acid or KBrO₃. However, the maximum resistance and extensibility of the rested dough containing 8% THGP, with and without ascorbic acid or KBrO₃, were not significantly different from those of the control dough. The addition of 8% THGP significantly increased the loaf volume of bread baked from non‐frozen dough when combined with 60 ppm ascorbic acid or 30 ppm KBrO₃, but it had a significant effect both with and without ascorbic acid or KBrO₃ on frozen‐dough bread. A large difference in volume was observed between breads made with and without THGP at the oven‐spring, rather than at proofing. CONCLUSION: The addition of 8% THGP increased the loaf volume of bread made from freeze‐damaged dough and this effect increased when THGP was combined with 60 ppm ascorbic acid. Copyright © 2008 Society of Chemical Industry     

De‐esterification of pectin by alkali,plant and fungal pectinmethylesterases and effect on molecular weight

Commercial high methoxyl pectin was de‐esterified using chemical saponification or by pectinmethylesterases. A commercial fungal pectin methyl esterase (PME) (EC 3.1.1.11), free of polygalacturonase, or a citrus Valencia PME was used to de‐esterify pectin enzymatically to a targeted degree of esterification. The apparent molecular weight of pectin did not change by extended times of Valencia PME treatment and ranged from 154100 to 183500. Fungal PME‐modified pectins had moderately increased apparent molecular weight that ranged from 123900 to 169800. The increase in molecular weight was attributed to aggregation. The molecular weight of pectins that were de‐esterified by alkali decreased from about 156200 to 91200. Citrus Valencia or fungal PME modification alters the charge of pectin without loss of high molecular weight. Copyright © 2005 Society of Chemical Industry     

酰胺化果胶的特性、应用及生产和研究状况

对果胶类型做了概括介绍,将酰胺化果胶与普通低酯果胶以及高酯果胶进行多方面的比较,突出酰胺化果胶的特性。结合国内外对酰胺化果胶生产的研究现状,以及其在食品工业和医疗方面的应用现状,对酰胺化果胶生产的发展前景进行了分析。     

On the formulation design and rheological evaluations of pectin-based functional gels

In the current study, formulation design and development of a novel pectin-based functional gel were investigated. Amidated low methoxyl pectin (ALMP), high methoxyl pectin (HMP), sorbitol, inulin, rebaudioside-A, gardenia, phloridzin, quercetin, apple flavor, and calcium chloride (as its dihydrated salt) were selected as general ingredients. Response surface methodology was applied to design different formulations and to investigate on their experimental responses. The oscillatory tests were carried out in 2 stages with ALMP, HMP, sorbitol, and inulin as the variables of the 1st stage and ALMP and calcium chloride as the variables of the 2nd stage. Results of the 1st stage indicated relatively similar behaviors throughout the frequency range applied for all of the samples studied (true gels). However, magnitudes of the 5 rheological parameters of this study (storage modulus, loss modulus, loss tangent, complex modulus, and complex viscosity) were affected by different variables (ALMP, HMP, inulin, and sorbitol concentrations). Experimental results confirmed that sorbitol could be omitted from the formula while inulin and HMP could be used at their highest levels studied. At the 2nd stage, only 2 formulas indicated a strong gel behavior and other formulas showed typical behaviors of weaker gels or those of the concentrated solutions. At the conclusion of this study, a finished gelled product formula was suggested with the application of the best levels of the ingredients. The resultant gel was found to be set rapidly with no syneresis and showed a potential to be considered as a functional gelled dessert.     

Characterization of pectin extracted from banana peels of different varieties

Pectins were extracted from banana peels of five different varieties using citric acid solution. The chemical characteristics of banana peel pectins were investigated and compared with citrus peel and apple pomace pectins which were extracted under the same extraction conditions to assess the potential of banana peels as an alternative source of commercial pectin. The yield of banana peel pectins ranged from 15.89 to 24.08%. The extracted banana peel pectins were categorized as high methoxyl pectin with the degree of esterification between 63.15 and 72.03% comparable to those of conventional pectin sources from citrus peel (62.83%) and apple pomace (58.44%). The anhydrouronic acid (AUA) content of banana peel pectins varied from 34.56 to 66.67%. Among various banana varieties being studied, pectin from Kluai Nam Wa variety had the highest AUA content (66.67%) which met the criteria for food additive pectin indicating its commercial significance as an alternative pectin source.     

High methoxyl pectin–methyl cellulose films with antioxidant activity at a functional food interface

The effect of using increasing proportions of methylcellulose (MC) for the development of glycerol plasticized films based on high methoxyl pectin (HMP) (30:70, 50:50 and 70:30 w/w HMP:MC) and carrying l-(+)-ascorbic acid (AA) was studied with the purpose of achieving higher stability of AA and localized antioxidant activity at food interfaces. MC and 30:70 HMP:MC systems could not be casted. The shelf-life of the other AA-active films was assessed by storage at 25 °C, constant relative humidity (RH: 33.3%, 57.7% and 75.2%) and vacuum conditions. The rate constant for AA hydrolysis increased with the RH and, hence, with water mobility. Browning and AA degradation rates were directly related. When stored at 75.2% RH, both decreased as MC proportion increased. Compared to HMP film, the highest proportion of MC (50:50 HMP:MC) showed the highest AA stabilization under vacuum and greater performance under air atmosphere. They also developed localized antioxidant activity preserving the tocopherol content of walnut oil.     

Extraction and characterization of pectin from Yuza (Citrus junos) pomace: A comparison of conventional-chemical and combined physical–enzymatic extractions

Pectin from Yuza (Citrus junos) pomace was extracted by using combined physical and enzymatic (CPE) treatment, and their characteristics were compared with those of chemically-extracted pectin. Their physico-chemical and thermo-mechanical properties were also investigated in a wheat flour–water system. The CPE extraction produced pectin with 55% of galaturonic acid and the extraction yield was 7.3%. Also, the pectin obtained by CPE extraction exhibited a higher degree of esterification (46%) than chemically-extracted pectin (41%), which was confirmed by FT-IR analysis. When the pectin solutions were subjected to steady-shear conditions, both samples had shear-thinning properties while high apparent viscosity was observed in the chemically-extracted pectin. Even though the use of both pectins raised the pasting parameters of wheat flour as well as its gelatinization temperature, less change in the pasting properties was found in the wheat flour–water system containing the pectin prepared by CPE treatment. The Mixolab results demonstrated that during mechanical shearing and thermal treatments, the dough samples containing chemically-extracted pectin exhibited enhanced mixing stability, strong protein network structure, and increased peak viscosity.