Hydrocolloid interferences in the determination of pectin by the carbazole method.

In the colorimetric determination of pectin by the carbazole method, some of the interfering compounds have been identified but the possible interference of different hydrocolloids is not known. Several hydrocolloids are currently used in the preparation of imitation and adulterated orange juice for cloud stabilization. Hydrocolloids studied were gum arabic, carboxylmethyl cellulose, sodium alginate, carrageenan, guar gum, and xanthan. The effects of these hydrocolloids on the carbazole method for pectin determination was studied. Procedures are proposed for the correct use of the carbazole method for pectin determination in the presence of extraneous hydrocolloids.     

Comparative study of thermal degradation behavior of graft copolymers of polysaccharides and vinyl monomers

The thermal degradation of graft copolymers of both polysaccharides (guar gum and xanthan gum) showed gradual decrease in mass loss. Pure guar gum degraded about 95% but pure xanthan gum degraded about 76% up to 1173.15 K, while graft copolymers of guar gum and xanthan gum degraded only 65–76% up to 1173.15 K. Acrylic acid grafted guar gum and xanthan gum showing two-step degradation with formation of anhydride and ketonic linkage during heating, same pattern of degradation was found for xanthan gum-g-methacrylic acid. Guar gum-g-acrylamide degraded in single step and xanthan gum-g-acrylamide started to degrade above 448.15 K and it is a two-stage process and imparts thermal stability due to the formation of imide linkage with evolution NH₃. Guar gum-g-methacrylamide degraded in three steps due to the loss of NH₃ and CO₂ successively. 4-vinyl pyridine grafted both polysaccharides show single step degradation due to loss of pyridine pendent. N-vinyl formamide grafted guar gum and xanthan gum started to degrade at about 427.15 K, showed two-stage degradation process with the evolution of CO and NH₃ molecules while guar gum-g-(N-vinyl-2-pyrrolidone) degraded into two steps by the loss of pyrrolidone nucleus. Gum-g-2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) showed two-step degradation processes in two successive degradation steps, while xanthan gum-g-AMPS has started degradation at about 427.15 K and completed in five degradation steps. Overall, it was found that the grafted polysaccharides are thermally more stable than pure polysaccharides.     

Nutritional, antioxidant, and glycaemic characteristics of new functional bread

New wheat-rye bread fortified with cereal dietary fibre, β-glucan hydrogel, and sourdough starter culture was designed in this study. The impact of these additives on nutritional composition and antioxidant properties was investigated. Functional bread with extruded wheat bran (10.0 %), cereal β-glucan hydrogel (12.5 %), and lactobacilli starter culture was compared with traditional wheat-rye bread (control). The contents of basic nutrients (protein, fat, etc.), dietary fibre, biologically active compounds (polyphenols and flavonoids), qualitative and quantitative analysis of simple saccharides and phenolic acids (by HPLC) were analysed in both bread types. Antioxidant activity, measured by two spectrophotometric methods (2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonic acid); ABTS and di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (2,2-diphenyl-1-picrylhydrasyl); DPPH, was also evaluated. The effect of the addition of the above ingredients, as compared with traditionally prepared bread, was examined in the postprandial study, in which glucose and insulin levels were determined. In comparison with the control bread, higher amounts of dietary fibre, flavonoid content, and antioxidant activity were attained in the designed bread. Consumption of the designed bread led to reduced glucose levels in healthy males (n = 10) 120 min after the ingestion of the functional bread compared with the control (p < 0.048). No statistically significant change in the insulin response in the volunteers was observed after consumption of the designed bread compared with the control.     

Unique properties of high viscosity gums

Guar gum, a galactomannan from the seed endosperm of the legume, Cyamopsis tetragonolobus, is an important food stabilizer used in a variety of food products ranging from sauces to ice cream. Two guars having viscosities 13-250% higher than conventional guars were studied. Viscosity, effect of shear rate on viscosity, synergy with xanthan gum, granulation, galactomannan content, molecular weight, and scanning electron microscopy of the guar types were evaluated. At equal usage levels of guar, the high viscosity type showed a higher viscosity alone and in combination with xanthan gum under all conditions tested. The high viscosity products have electron microscopic morphology that is more elongated and molecular weights which are greater than normal guars. These factors are discussed in light of the viscosity differences which exist between these products.     

A Study of the Effects of Aeration and Agitation on the Properties and Production of Xanthan Gum from Crude Glycerin Derived from Biodiesel Using the Response Surface Methodology

The effects of aeration and agitation on the properties and production of xanthan gum from crude glycerin biodiesel (CGB) by Xanthomonas campestris mangiferaeindicae 2103 were investigated and optimized using a response surface methodology. The xanthan gum was produced from CGB in a bioreactor at 28 °C for 120 h. Optimization procedures indicated that 0.97 vvm at 497.76 rpm resulted in a xanthan gum production of 5.59 g L^?1 and 1.05 vvm at 484.75 rpm maximized the biomass to 3.26 g L^?1. Moreover, the combination of 1.05 vvm at 499.40 rpm maximized the viscosity of xanthan at 0.5 % (m/v), 25 °C, and 25 s^?1 (255.40 mPa s). The other responses did not generate predictive models. Low agitation contributed to the increase of xanthan gum production, biomass, viscosity, molecular mass, and the pyruvic acid concentration. Increases in the agitation contributed to the formation of xanthan gum with high mannose concentration. Decreases in the aeration contributed to the xanthan gum production and the formation of biopolymer with high mannose and glucose concentrations. Increases in aeration contributed to increased biomass, viscosity, and formation of xanthan gum with greater resistance to thermal degradation. Overall, aeration and agitation of CGB fermentation significantly influenced the production of xanthan gum and its properties.     

瓜儿豆胶和刺槐豆胶抑制阿斯巴甜甜感强度的机制探索

目前大分子水溶胶对于味觉物质的影响机制研究主要集中于胶体自身的性质以及胶体结构与味物质的相互作用.本文选择了食品中常用的瓜儿豆胶(GG)和刺槐豆胶(LBG),研究了这两种非离子水溶胶对甜味剂阿斯巴甜(APM)感官甜度的影响,并探索了其中的物理化学机制.感官实验结果表明,高浓度的瓜儿豆胶和刺槐豆胶对阿斯巴甜的甜度有抑制作用,且随着水溶胶浓度的增高,达到高分子临界交叠浓度C*后,抑制作用更明显.基于人工受体模型,利用等温滴定量热(ITC)技术发现,两种水溶胶存在条件下阿斯巴甜与受体模型相互作用的结合常数急剧减小.另外,通过对甜味剂存在下非离子水溶胶的水分分布、扩散性质的考察,发现随水溶胶浓度增加,体系的结合水含量均增多,尤其是水溶胶浓度达到临界交叠浓度(C*)后增多的现象更明显;同时,分子的扩散也受到了阻碍,从而导致阿斯巴甜感官甜度的降低.本研究表明,探索大分子水溶胶对甜味剂分子与受体结合差异性的影响、溶液中水分子的弛豫性质及赋存状态、结合体系的粘度及扩散性质的研究,为理解大分子水溶胶对甜味影响的物理化学机制提供更多的信息.     

Effect of hydrocolloids on starch thermal transitions,as measured by DSC

Differential scanning calorimetry (DSC) was used to analyze the influence of different hydrocolloids (xanthan, guar, and locust bean gums, carboxymethylcellulose and sodium alginate) on the gelatinization of corn starch in systems with starch concentration ranging between 0.1 and 0.7 g starch/g mixture. The reduction of available water produced a shift in gelatinization temperature, especially of the conclusion temperature. The effect was more marked for ionic hydrocolloids. The influence of hydrocolloids on glass transition temperature (T _g) of gelatinized starch suspensions and on the glass transition temperature of the maximally freeze-concentrated solute/unfrozen water matrix (T _g) was also studied.T _g onset values ranged between –4.5 and –5.5C for corn starch pastes with and without hydrocolloids. Those hydrocolloids that increased the viscosity of the unfrozen matrix inhibited additional ice formation during thawing (devitrification).Starch concentration and final heating temperature were found to be relevant factors affecting the kinetics of amylopectin retrogradation during frozen storage at –4C. Xanthan gum failed to prevent amylopectin retrogradation; this observation could be attributed to the fact that gums act outside the starch granule, while amylopectin retrogradation takes place within the granule.     

Preparation and Performance of Thickened Liquids for Patients with Konjac Glucomannan-Mediated Dysphagia

The present study sought to characterize the rheological and thickening properties of Konjac glucomannan (KGM) and prepare thickening components for special medical purposes using KGM and maltodextrin as the primary raw materials and guar gum (GG), xanthan gum (XG), locust bean gum (LBG), and carrageenan (KC) as the supplemented materials. The formulation and preparation processes were optimized through single factor experiments taking sensory evaluation as an indicator. The results confirm that KGM had excellent thickening performance, reaching about 90 times its own mass. The optimal formulation process of the thickening components based on KGM was as follows: the mass concentration of the compound thickener (KGM/GG/XG/LBG/KC = 13:2:2:2:1) was 5.0–7.0 mg/mL; the maltodextrin concentration was 10.0 mg/mL; the brewing temperature of the thickening component was 60 °C with no restriction on consumption time. The rheology test results revealed that the thickening components had shear thinning characteristics, which could provide three different thickening effects of nectar-thick level (350 mPa·s), honey-thick level (1250 mPa·s), and pudding-thick level (1810 mPa·s) suitable for people with different degrees of chewing disorders. Overall, this study provides a theoretical basis and technical reference for KGM as a dietary nutrition support for patients with dysphagia.     

Effect of Coconut Protein and Xanthan Gum,Soybean Polysaccharide and Gelatin Interactions in Oil-Water Interface

We report on our study of the interactions between coconut protein extracted from coconut meat and three hydrocolloids (gelatin, xanthan gum, and soybean polysaccharide) and their interfacial adsorption and emulsification properties. We used Zeta potential, fluorescence spectroscopy scanning and ITC to investigate the interactions between a fixed concentration (1%) of coconut protein and varying concentrations of hydrocolloid. Through the interfacial tension and interfacial viscoelasticity, the interfacial properties of the hydrocolloid and coconut protein composite solution were explored. The physical stability of the corresponding emulsion is predicted through microstructure and stability analysis. Xanthan gum forms a flocculent complex with coconut protein under acidic conditions. Soy polysaccharides specifically bind to coconut protein. Under acidic conditions, this complex is stabilized through the steric hindrance of soy polysaccharides. Due to gelatin-coconut protein interactions, the isoelectric point of this complex changes. The interfacial tension results show that as time increases, the interfacial tensions of the three composite solutions decrease. The increase in the concentration of xanthan gum makes the interfacial tension decrease first and then increase. The addition of soybean polysaccharides reduces the interfacial tension of coconut protein. The addition of xanthan gum forms a stronger elastic interface film. Emulsion characterization showed that the gelatin-added system showed better stability. However, the addition of xanthan gum caused stratification quickly, and the addition of soybean polysaccharides also led to instability because the addition of polysaccharides led to a decrease in thermodynamic compatibility. This research lays the foundation for future research into coconut milk production technology.     

Synthesis and Characterization of an Exopolysaccharide by Antarctic Yeast Strain <Emphasis Type="Italic">Cryptococcus laurentii</Emphasis> AL<Subscript>100</Subscript>

An exopolysaccharide-producing Antarctic yeast strain was selected and identified as Cryptococcus laurentii AL₁₀₀. The physiological properties of the strain and its ability to utilize and biotransform different carbon sources (pentoses, hexoses, and oligosaccharides) into exopolysaccharide and biomass were investigated. Sucrose was chosen as a suitable and accessible carbon source. The biosynthetic capacity of the strain was studied in its dynamics at different sucrose concentrations (20, 30, 40, and 50 g/L) and temperatures (22 and 24 °C). The maximum biopolymer quantity of 6.4 g/L was obtained at 40 g/L of sucrose, 22 °C temperature and 96-h fermentation duration. The newly synthesized microbial carbohydrate was a heteropolysaccharide having the following monosaccharide composition: arabinose, 61.1%; mannose, 15.0%; glucose, 12.0%; galactose, 5.9%; and rhamnose, 2.8%. It was characterized by polydispersity of the polymer molecule, 60% of it having molecular mass of 4200 Da. The exopolysaccharide demonstrated good emulsifying and stabilizing properties with regard to oil/water emulsions and a pronounced synergistic effect with other hydrocolloids such as xanthan gum, guar gum, and alginate.     

Improvement of the electrophoretic protein profiles of Leguminosae gums extracts using gamanase and application to the evaluation of carob-guar mixtures

A quantitative assay for guar gum in carob gum, based on the extraction of proteins in acetonitrile-water (7:3), separation by capillary electrophoresis and multiple linear regression (MLR) using the areas of nine selected peaks as predictors, was improved by performing the extraction in the presence of gamanase. In the absence of the enzyme, peak migration times and areas depended on the guar content, which complicated peak identification and evaluation. Manual correction of the migration times by comparison with standard electropherograms obtained with pure carob and carob-guar mixtures was required; however, when the proteins were extracted under sonication at 60 °C for 30 min in the presence of gamanase, the migration times and peak areas did not vary with the composition of the carob-guar mixtures, and its reproducibility improved largely. These effects were attributed to the reduction of the viscosity of the extracts and the removal of the galactomannose interactions with the proteins and the capillary walls. Peak identification and evaluation were easily and directly performed on these electropherograms without further processing. An MLR model constructed with 36 carob-guar mixtures containing up to 20% guar, and by measuring the areas of 12 selected peaks and using eight of them as predictors, yielded a detection limit of 2.8% guar (α=β=0.05 criterion). A model of similar quality was obtained by partial least-squares (PLS) regression.     

Effect of Coconut and Chestnut Flour Supplementations on Texture,Nutritional and Sensory Properties of Baked Wheat Based Bread

Wheat bread, produced by the single-phase method, is a common food consumed all over the world. Due to changes in lifestyle and nutritional trends, alternative raw materials are sought to increase the nutritional value and improve the taste of daily consumed products. Additionally, customers seek a wide variety of foods, especially when it comes to basic foods. Nuts, such as coconuts or chestnuts, might provide an attractive flavour with benefits to the nutritional quality. In this study, the effect of substituting wheat flour with coconut or chestnut flour (flour contribution level: 5, 10, 15, 30, 50% w/w), was evaluated in terms of the breads specific volume, texture, colour, nutritional composition, and dietary fibre fraction contents. Moreover, a sensory evaluation was conducted to assess potential consumer acceptance. Based on the consumer’s perception, the overall acceptance of bread with 15% w/w of coconut and chestnut flour was in privilege compared to the control sample. As a result, taking all of the tested parameters into account, the breads with 5, 10, and 15% supplementation of chestnut or coconut flour were still of good quality compared to the wheat bread and their fibre content was significantly higher.     

Preparation,Characterization and Anticoagulant Activity of Guar Gum Sulphate

Guar gum was chemically modified by sulphonation using chlorosulphonic acid (ClSO₃H) as a reagent. Effects of molar ratio of ClSO₃H to glucopyranosic unit (ClSO₃H/GU), reaction time and reaction temperature on the degree of sulphonation (DS) and molecular weight (Mw) of products were studied. The structures of guar gum sulphate were investigated by GPC, FT‐IR and UV‐Visible spectroscopy. Activated partial thromboplastin time (APTT) assay showed that the guar gum sulphate could inhibit the intrinsic coagulant pathway. The anticoagulant activity strongly depended on the DS and Mw of polysaccharides. DS>0.56 was essential for anticoagulant activity. The guar gum sulphate with the DS of 0.85 and the Mw of 3.40×10⁴ had the best blood anticoagulant activity.     

Influence of mechanical stress on the molar mass distribution and the rheological behavior of polysaccharides

The mechanical stress acting on hydrocolloid macromolecules in flow processes may change the molecular structure, the rheological properties, affecting the technical function and thereby the properties. This paper introduces a newly developed method for definite “mechanical stress treatment” of xanthan and guar gum. Rheological measurements (intrinsic viscosity) and chromatography (GPC) allowed the resulting rheological and structural changes to be quantified.     

Interaction of gums (guar, carboxymethylhydroxypropyl guar, diutan, and xanthan) with surfactants (DTAB, CTAB, and TX-100) in aqueous medium

The interaction of surfactants dodecyltrimethylammonium bromide (DTAB), cetyltrimethylammonium bromide (CTAB), and p-tert-octylphenoxypolyoxyethylene (9.5) ether (TX-100) with guar (Gr), carboxymethylhydroxypropyl guar (CMHPG), diutan (Dn), and xanthan (Xn) gums has been studied employing conductometry, tensiometry, microcalorimetry, viscometry, and atomic force microscopy (AFM) techniques. Both weak and strong interactions were observed. CTAB interacted stronger than DTAB with the gums. The surfactant-gum interaction process was enhanced by the presence of borate ions in the solution; the borate ion itself also manifested interaction with the surfactants comparable with that of water-soluble polymers polyvinyl alcohol, polyoxyethylene, and so forth. Viscometric results supported configurational changes of the gum molecules by interaction with surfactants. The geometry of the pure gums and their CTAB interacted products in the dried states was ascertained from AFM measurements; spherical and prolate shapes were observed for pure gums, and distorted states were observed for their surfactant complexed species. Detailed topological features of these entities were ascertained.     

Feasibility of Polyvinyl Alcohol as a Transdermal Drug Delivery System for Terbutaline Sulphate

A series of terbutaline sulphate drug incorporated polyvinyl alcohol (PVA) matrix films were produced by the solvent evaporation method. The effect of xanthan gum and plasticizers (propylene glycol and dibutyl phthalate) on the rate and amount of drug diffusion from PVA membrane across the hydrated cellophane membrane has been evaluated, using an open glass diffusion‐tube. The obtained films were clear, smooth and flexible having sufficient mechanical strength. The mechanical performance of the dry PVA films with xanthan gum and plasticizers were also ascertained. Polyvinyl alcohol‐xanthan gum blends showed a high rate of drug release compared to that of polyvinyl alcohol film alone. Among the two plasticizers employed, propylene glycol showed better permeability. Among different formulations studied, the formulation PVA/xanthan gum/propylene glycol (F7) was found to be an optimized composition for efficient transdermal delivery of the model drug, terbutaline sulphate. The mechanism of drug diffusion has been evaluated using the Peppas model. Stability studies carried out on polymer‐drug formulations revealed that the drug is stable at 40°C and 75% RH for a period of 6 weeks.     

Determination of locust bean gum and guar gum by polymerase chain reaction and restriction fragment length polymorphism analysis

A polymerase chain reaction (PCR) was developed to differentiate the thickening agents locust bean gum (LBG) and the cheaper guar gum in finished food products. Universal primers for amplification of the intergenic spacer region between trnL 3' (UAA) exon and trnF (GAA) gene in the chloroplast (cp) genome and subsequent restriction analysis were applied to differentiate guar gum and LBG. The presence of <5% (w/w) guar gum powder added to LBG powder was detectable. Based on data obtained from sequencing this intergenic spacer region, a second PCR method for the specific detection of guar gum DNA was also developed. This assay detected guar gum powder in LBG in amounts as low as 1% (w/w). Both methods successfully detected guar gum and/or LBG in ice cream stabilizers and in foodstuffs, such as dairy products, ice cream, dry seasoning mixes, a finished roasting sauce, and a fruit jelly product, but not in products with highly degraded DNA, such as tomato ketchup and sterilized chocolate cream. Both methods detected guar gum and LBG in ice cream and fresh cheese at levels <0.1%.     

Effect of high-dose irradiation and autoclave treatment on microbial safety and quality of ready-to-eat Bulgogi sauce

In Korea, commercialized sauce for ready-to-eat (RTE) Bulgogi is usually manufactured using heat treatment to ensure that it has a long shelf-life. However, heat treatment may adversely affect the taste and flavor of the sauce, thus, the development of suitable sterilizing methods for RTE sauces is necessary to preserve the quality of the sauce during long storage periods. In this study, total bacterial growth, the viscosity, and the sensory properties of Bulgogi sauce were compared between sterilization with gamma irradiation (0–40 kGy) and autoclave treatment during storage at 35 °C for 90 days. No bacterial growth was observed following irradiation at more than 10 kGy or after autoclave treatment. However, the viscosity and sensory properties of samples gamma-irradiated at above 10 kGy or autoclave-treated were significantly changed, even though autoclave treatment induced a burnt taste and flavor. Therefore, a gamma irradiation of 10 kGy was effective to prepare ready-to-eat Bulgogi sauce with microbial safety and original sensory qualities.     

Co-gelation mechanism of xanthan and galactomannan

Synergistic gelation of dilute (0.1% total gums) mixed solutions of xanthan and galactomannan isolated from seeds of Delonix regia was investigated. Gelation occurred in a mixed solution of xanthan and galactomannan at 0.1% total gums at room temperature (25 °C). The flow curves of mixed solutions of native xanthan and galactomannan showed plastic behavior. The maximum elastic modulus was obtained when the ratio of the xanthan to galactomannan was 2:1 at room temperature (25 °C). The largest elastic modulus was observed in the mixture solution of deacetylated xanthan. However, a small elastic modulus was obtained in the mixture with depyruvated xanthan. The results obtained supported the interaction mechanism between xanthan and galactomannan (locust bean gum) previously proposed, and the pyruvate methyl groups might also take part in the interaction.     

Effect of Octenyl Succinic Anhydride (OSA) Modified Starches on the Rheological Properties of Dough and Characteristic of the Gluten-Free Bread

The study focused on the influence of starch modified by octenyl succinic anhydride (OSA) on the rheological and thermal properties of gluten-free dough containing corn and potato starch with the addition of pectin and guar gum as structure-forming substances. The starch blend used in the original dough recipe was partially (5% to 15%) replaced with OSA starch. The rheological properties of dough samples were determined, and the properties of the resulting bread were analyzed. It was found that the dough samples behaved as weak gels, and the values of storage and loss moduli (G′ and G″, respectively) significantly depended on angular frequency. Various shares of OSA starch in recipes modified dough in different ways, causing changes in its rheological characteristics. The introduction of OSA starch preparations resulted in changes in the bread volume and physical characteristics of the crumb. All the applied preparations caused an increase in bread porosity and the number of pores larger than 5 mm, and there was a parallel decrease in pore density. The presence of OSA starch preparations modified bread texture depending on the amount and type of the applied preparation. The introduction of OSA starches in gluten-free bread formulation caused a significant drop in the enthalpy of retrograded amylopectin decomposition, indicating a beneficial influence of such type of additive on staling retardation in gluten-free bread.