Showing papers on "Gum arabic published in 2009"

Handbook of hydrocolloids.

Abstract: Introduction. Agar. Starch. Gelatin. Carrageenan. Xanthum Gum. Gellan Gum. Gallactomannans. Gum Arabic. Pectins. Milk Proteins. Cellulosis. Tragacanth and Karaya. Xyloglucan. Curdlan. Glucans. Soluble Soybean Polysaccharide. Bacterial Cellulose. Microcrystalline Cellulose. Gums for Coating and Adhesives.Chitosan Hydrogels. Alginates. Frutafit-Inulin. The CRC Emulsifying Biopolymer.

Physicochemical and morphological characterisation of açai (Euterpe oleraceae Mart.) powder produced with different carrier agents

Abstract: Physicochemical and morphological properties of ac¸ai powder produced with different carrier agents were evaluated in this work. Powders were produced by spray drying, using maltodextrin 10DE, maltodextrin 20DE, gum arabic and tapioca starch as carrier agents. Powder characterisation included analysis of moisture content, water activity, solubility, hygroscopicity, particle size distribution, morphology, total polyphenolics and antioxidant activity. Results showed that the samples produced with maltodextrin 20DE and gum arabic presented the smallest size and highest hygroscopicity. The powder produced with tapioca starch exhibited the lowest hygroscopity and solubility, and the highest mean diameter. With regard to morphology, all particles exhibited spherical and shrivelled surfaces, except those produced with tapioca starch, which exhibited rounded and smooth surfaces. Powders produced with maltodextrins and gum arabic showed high polyphenolic retention and antioxidant activity preservation after storage at 40 _C for 15 days, while for the particles produced with tapioca starch, this protective effect was less pronounced. (Resume d'auteur)

Effect of pH, salt, and biopolymer ratio on the formation of pea protein isolate-gum arabic complexes.

Abstract: Turbidity measurements were used to study the formation of soluble and insoluble complexes between pea protein isolate (PPI) and gum arabic (GA) mixtures as a function of pH (6.0-1.5), salt concentration (NaCl, 0-50 mM), and protein-polysaccharide weight mixing ratio (1:4 to 10:1 w/w). For mixtures in the absence of salt and at a 1:1 mixing ratio, two structure-forming transitions were observed as a function of pH. The first event occurred at a pH of 4.2, with the second at pH 3.7, indicating the formation of soluble and insoluble complexes, respectively. Sodium chloride ( 7.5 mM) due to substantial PPI aggregation. The pH at which maximum PPI-GA interactions occurred was 3.5 and was independent of NaCl levels. As PPI-GA ratios increased, structure-forming transitions shifted to higher pH.

Encapsulation Performance of Proteins and Traditional Materials for Spray Dried Flavors

Abstract: The objective of this study was to evaluate the potential of selected proteins as alternative materials for flavor encapsulation by spray drying. Two traditional materials (gum acacia and modified starch) and three proteins (sodium caseinate, whey and soy protein isolates) were used at different infeed solid levels; test compounds included (R)-(+)-limonene and three alpha,beta-unsaturated aldehydes ((E)-2-hexenal, (E)-cinnamaldehyde, citral). The primary criteria for performance were flavor retention during drying and protection against losses during storage. Limonene oxidation and nonenzymatic browning were investigated as two possible deterioration routes. Overall, higher infeed solids improved retention during drying and limited flavor losses (aldehydes and limonene) during storage in traditional materials only. The materials giving the highest flavor retention during drying were gum acacia (94%), modified starch (88%) and whey protein isolate (87%). Gum acacia provided the highest retention of aldehydes during storage (37 to 58%) after 28 days at 40 degrees C but did not afford good protection against limonene oxidation. Oppositely, protein materials effectively limited limonene oxidation (>70% retained). Nonenzymatic browning was observed for all powders prepared with proteins, especially whey protein isolate, whereas no browning occurred with traditional materials.

Effect of maltodextrin and gum arabic on water sorption and glass transition temperature of spray dried chicken meat hydrolysate protein

Abstract: The water adsorption isotherm and glass transition temperatures (Tg) of chicken protein hydrolysate powder, with and without maltodextrin or gum Arabic, were studied in order to investigate their stability. The hydrolysate powder, pure and formulated with 10%, 20% and 30% (w/w) of additive, was obtained by spray drying. The sorption isotherm was determined by the gravimetric method. A differential scanning calorimeter was used to determine the Tg of samples equilibrated with several water activities. As results, the BET model fitted the data for the sorption isotherm of the protein hydrolysate well. A strong plasticizing effect of water on the Tg was found, with a great reduction in this value with increase in water activity. The data for Tg versus solids content gave a satisfactory correlation with the Gordon-Taylor model. The addition of carrier agents increased the Tg of the hydrolysate, decreasing its hygroscopicity and, consequently, increasing its storage stability.

Adsorption of Gum Arabic, Egg White Protein, and Their Mixtures at the Oil−Water Interface in Limonene Oil-in-Water Emulsions

Abstract: The adsorption behavior of gum Arabic, egg white protein, and their mixtures at the oil−water interface for 20% limonene oil emulsions has been investigated at pH 3.5 and 7.5. It has been shown that protein-rich fractions of gum Arabic adsorb onto limonene oil droplets and that there is no significant molecular mass dependence. The amount adsorbed was determined from differences in the intensities of the gel permeation chromatography elution profiles of the gum before and after preparing emulsions and was found to be 6.5 and 5 mg/m2 at pH 3.5 and 7.5, respectively. These values are greater than might be expected for monolayer coverage. The amount of protein associated with the gum Arabic adsorbed was about 0.25 mg/m2, which corresponds to 26% of the total protein present in the gum. In comparison, the amount of egg white protein adsorbed was found to be 1.2 and 0.8 mg/m2, respectively, at pH 3.5 and 7.5, which are typical values for monolayer coverage. For gum Arabic−egg white protein mixtures (1:0.05 w/w corresponding to 1:1 on a molar basis) at pH 7.5, both species are negatively charged, and there is no interaction between them. On formation of emulsions, they compete with each other for surface sites, and egg white protein molecules are adsorbed preferentially, although not exclusively. At pH 3.5, the molecules have opposite charge and interact and at this ratio form soluble electrostatic complexes, which are adsorbed at the interface during emulsification. The droplet size of emulsions prepared with gum Arabic was significantly less than for egg white protein over the concentration range studied. Gum Arabic−egg white protein mixtures (1: 0.05 w/w) at pH 3.5 produced emulsions with a droplet size similar to gum Arabic alone, while those prepared at pH 7.5 produced emulsions with a significantly larger droplet size.

Molecular associations in acacia gums

Abstract: The tendency of polysaccharides to associate in aqueous solution has long been recognised. Molecular associations can profoundly affect their performance in a given application due to its influence on the molecular weight, shape and size. This will ultimately determine how the molecules will interact with each other, with other molecules and with water. There are several factors, such as hydrogen bonding, hydrophobic association, ion mediated association, electrostatic interaction, concentration dependence and the presence of proteinaceous components, which affect this behaviour. Our objective is to highlight the role of the proteinaceous component, present in acacia gum, to promote associations when the gum is subjected to various processing treatments such as maturation, spray drying and irradiation. The results demonstrate the ability of the proteinaceous component to promote hydrophobic associations which influence the size and proportion of the arabinogalactan high molecular weight component (AGP). Heat treatment in solid state (maturation) increases the hydrophobic character of the gum and hence its emulsification performance. Spray drying also involves aggregation through hydrophobic association but changes the surface properties of peptide moieties to become more hydrophilic compared to the association promoted by the maturation treatment in the solid state. Irradiation induced cross-linking, in the presence of unsaturated gas, was used to introduce C–C bonds into the carbohydrate moiety and thus confirms the hydrophobic association prompted by the heat used in the maturation and spray drying. This association can be reversed by treatments, such as filtration or high pressure homogenisation. The results reported here reconcile the contradiction about structure of gum arabic proposed by the wattle-blossom and twisted hairy rope models and shows that the AGP fraction is basically an aggregated fraction made up of AG units stabilized by low molecular weight highly proteinaceous components.

11 – Gum arabic

Abstract: : This chapter provides a review of the science and technology of gum arabic It includes a section concerned with the source and market trends of the material together with how it is collected, graded and processed The precise definition of gum arabic is discussed There has been much work undertaken on the chemical and physicochemical characteristics of the gum and this chapter summarises developments in this area and presents the latest views on the molecular structure In summary the gum is believed to contain three distinct fractions which all consist of a highly branched carbohydrate structure and which differ principally in their molecular mass and protein contents These are now commonly referred to as the arabinogalactan-protein, arabinogalactan and glycoprotein fractions The key functional characteristics of the gum are that it forms viscous solutions only at high concentrations and that it is able to stabilise oil-in-water emulsions Indeed it is the emulsifier of choice in the beverage industry The relationship between the structural characteristics of the gum and its functional properties is discussed The recent work on the health benefits of gum arabic is also reviewed

Effects of Two Emulsifiers on Yield and Storage of Flaxseed Oil Powder by Response Surface Methodology

Abstract: Response Surface Methodology (RSM) was used to establish optimum conditions for Flaxseed Oil (FO), soy lecithin and xanthan gum to yield stable Flaxseed Oil Droplet (FOD) and high Microencapsulation Efficiency (M.E.E). Gum arabic and maltodextrin were used at constant ratio of 1:1 . Flaxseed oil loading (20-35%), lecithin (1-2%) and xanthan gum (0.1-0.4%) were studied regarding their effects on emulsion and the spray dried powder. Results indicated response surface models significantly fitted to all response variables studied. Regression models describing variations of responses of FOD and M.E.E showed high coefficient of determination (R ) of 0.9963 and 0.9944 respectively. Overall numerical 2 optimization predicted desirable system attainable by combined 10% (w/w) each arabic gum and maltodextrins, 22.78% (w/w) flaxseed oil loading, 1.14% (w/w) soy lecithin and 0.10% (w/w) xanthan gum, which in turn resulted into FOD of 446.9 nm, M.E.E of 92.3% and strong physical barrier towards oxidation during 10 weeks of storage tests.

Other exudates: tragancanth, karaya, mesquite gum and larchwood arabinogalactan

Abstract: The collection, processing and trading of plant exudate gums, other than gum arabic, and the production of arabinogalactan from the heartwood of Western larch tree represent an important economic activity in many regions of the world. What this family of materials shares in common is that they are comprised of highly branched heteropolysaccharide structures. This chapter addresses the manufacture, chemical structure, functional properties, main applications and regulatory issues for three well- established hydrocolloids, namely gum tragacanth, gum karaya and larchwood arabinogalactan along with those of mesquite gum, whose full potential utilization is still to be exploited in several fields of application.

Gum arabic establishes prebiotic functionality in healthy human volunteers in a dose-dependent manner - CORRIGENDUM

Abstract: The present study was undertaken to determine the prebiotic efficacy of gum arabic upon consumption by man for up to 4 weeks and, if any, to establish the dose-effect relationship. Human healthy volunteers consumed various daily doses (5, 10, 20, 40 g) of gum arabic (EmulGold) in water for up to 4 weeks. Daily consumption of water was taken as the negative control and that of 10 g inulin as the positive control. At 0, 1, 2 and 4 weeks quantification of bacterial numbers in stool samples was performed via real time-PCR techniques and questionnaires were filled in to account for potential drawbacks. The genera of Bifidobacteria and Lactobacilli were taken as potentially beneficial bacteria and those of Bacteroides, Clostridium difficile and Enterococci as potentially non-beneficial, this distinction was dependent on the issue of these numbers being or becoming out of balance in the host. Compared with the negative control the numbers of Bifidobacteria and Lactobacilli 4 weeks after consumption were significantly higher for gum arabic: the optimal dose being around 10 g. Moreover, at this dose the numbers of Bifidobacteria, Lactobacilli and Bacteroides were significantly higher for gum arabic than for inulin. No significant drawback was encountered during the study. It is concluded that gum arabic establishes prebiotic efficacy, at least as good as inulin. The optimal daily dose was found to be 10 g.

Elicitation of guggulsterone production in cell cultures of Commiphora wightii by plant gums

Abstract: Plant gum as an elicitor for guggulsterone production in cell cultures of Commiphora wightii is reported for the first time. Guggulsterone production increased 2.4 fold in the cell cultures by gum Arabic (100 mg l−1), while mesquite gum elicited 2 fold. The cells treated with gum Arabic at 7th and 9th day accumulated enhanced guggulsterones within 24 h, which increased further up to 48 h and then declined. The cells treated at 9th day accumulated higher amount (218 μg l−1) of guggulsterones after 48 h of elicitation as compared to cells treated at 7th day (164 μg l−1). The optimized elicitation conditions were used in vessels of varying capacity where maximum yield of 285 μg l−1 of guggulsterones was recorded in 3 l shake flasks. These experiments enabled highest guggulsterones yield in a short duration of 11 days in cell cultures of C. wightii.

Isolation and characterization of microsatellite markers for Acacia senegal (L.) Willd., a multipurpose arid and semi-arid tree.

Abstract: Acacia senegal is a multipurpose African tree that improves the soil fertility of degraded areas. The species is exploited mainly for gum arabic, but it also supplies fuel wood and fodder for animals. Despite its wide distribution in Africa, no microsatellite markers have yet been characterized for this species. In this study, we characterized 11 polymorphic microsatellite loci specifically designed for A. senegal and analysed 247 individuals from three populations from Niger. On average, 10.9 alleles per locus were detected and expected heterozygosity ranged from 0.160 to 0.794, showing the ability of the markers to detect genetic diversity in this species.

Molecular association and function of arabinogalactan protein complexes from tree exudates

Abstract: Gum arabic is an exudate from the Acacia trees found in the arid conditions of the Sahelian belts of Africa. The particular gum discussed here is from the species Acacia senegal is a complex polydisperse molecule and is widely used in the food industry, mainly as a natural emulsifier. It is the high molecular weight arabinogalactan protein (AGP) component which is responsible for its emulsification functionality. A process is described which can increase the content and molecular weight of this component and as a result a new series of commercial gum arabic products have been produced, designated Acacia senegal(sey)SUPERGUM. The maturation process used to prepare these products is similar to that which occurs in the natural state of the tree. The paper describes how aggregation of the AGP can be controlled whereby low molecular weight components can be associated to form stable products. The mechanism of this association is discussed and explained in terms of inter-molecular equilibria. The results satisfactorily account for the large variation found in natural gum arabic and in commercial samples. Since this molecular variation can adversely affect the effectiveness of the gum arabic as an emulsifier, it is important that it can now be standardized and enhanced. There are indications that the basic building block of Acacia senegal is ca 400,000 Da but that aggregates of this unit can form depending on local conditions and commercial processing methods.