Composition Of Gum Research Articles

Gummosis in grape hyacinth (Muscari armeniacum) bulbs: hormonal regulation and chemical composition of gums

The purpose of this study was to investigate the hormonal regulation of gummosis in grape hyacinth (Muscari armeniacum) bulbs, focusing especially on the chemical composition of the gums. The application of ethephon (2-chloroethylphosphonic acid), an ethylene-releasing compound, at 1% and 2% (w/w) in lanolin as well as ethylene induced gummosis in the bulbs within several days. Methyl jasmonate (JA-Me, 0.1-2% in lanolin) alone had no effect on gummosis. However, simultaneous application of JA-Me and ethephon led to extreme stimulation of ethephon-induced gummosis. Ethephon-induced gummosis in the bulbs depended on the maturation stage of the bulbs, increasing from April to July, but decreasing from August to September. Regardless of the presence of JA-Me, the application of ethephon to the inflorescence axis of grape hyacinths did not induce gummosis. Gel permeation chromatography analysis revealed that gums were homogenous polysaccharides with an average molecular mass of ca. 8.3 kDa. Analysis of the sugar composition of the gums after hydrolysis revealed that the molar ratio of Rha:Ara:Gal:GalA:GlcA was 25:10:40:7:15. These results suggest that principal factors of gummosis as well as the chemical composition of gums differ between species of bulbous plants.

Evaluation of biodegradability of epoxy‐guar gum composites

AbstractEpoxy composites incorporating natural components have been mainly limited to the use of natural fibers. However, there have been a few instances where polysaccharides have been used as particulate fillers in thermoset compositions. The present study investigated the effect of guar gum/hydroxypropyl guar gum as a filler on the degradative properties of epoxy composites at various filler concentrations, with reference to fungal degradation and soil burial tests. It was found that at higher filler concentrations, the degradation increased. Composites based on hydroxypropyl guar gum showed increased degradation initially but on prolonged exposure to the fungal environment, the difference between guar gum and the hydroxypropyl guar gum‐based composites was found to be marginal. Microscopic evaluation of the composites showed that the degradation occurred at both the composite surface and in the bulk. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Effect of Water on Mechanical Properties of Unsaturated Polyester—Acetylated Hydroxypropyl Guar Gum Composites

The use of natural, eco-friendly, renewable resources in composites, as a reinforcing material, requires chemical or physical treatment to improve compatibility with the polymer matrix. In the present study hydroxypropyl guar gum (HPG) was acetylated to investigate its influence on the behavior of its unsaturated polyester (UPR) composites on exposure to water. The kinetics of water diffusion and effect on mechanical properties were studied with respect to the degree of acetylation and filler concentration. The absorption behavior of all composites was found to follow Fick’s law. Mechanical properties of HPG composites were found to be superior compared to pure UPR and acetylated HPG composites.

Evaluation of mechanical properties of epoxy–guar gum composites

AbstractGuar gum (GG) and hydroxypropyl guar gum (HPG) are widely used in a variety of applications ranging from foods, pharmaceutics to mining and explosives. However, there have been very few studies conducted investigating the use of these materials as fillers in polymer composites. GG and HPG were incorporated in an epoxy matrix and the mechanical properties of the resultant composites were determined. The tensile strength, flexural strength, and impact strength of the composites indicate that they provide reinforcement to the composites upto 5–7.5 phr after which there is a rapid decrease in the respective properties. HPG with higher propoxy content was found to provide greater reinforcement due to its increased hydrophobic nature leading to greater polymer–filler interaction. The nature of the filler required that the water absorption and related tests be carried out. The composites showed increased water absorption and also weight loss on exposure to acid and alkali environments, with HPGs showing greater variations when compared with GG, making the composites susceptible to moisture. The study shows that these fillers make an inexpensive, eco‐friendly, and renewable addition to conventional organic and inorganic fillers where the composites do not come into immediate contact with water. POLYM. ENG. SCI., 48:124–132, 2008. © 2007 Society of Plastics Engineers

Gas chromatographic–mass spectrometric characterisation of plant gums in samples from painted works of art

This paper presents an analytical GC–MS procedure to study the chemical composition of plant gums, determining aldoses and uronic acids in one step. The procedure is based on the silylation of aldoses and uronic acids, released from plant gums by microwave assisted hydrolysis, and previously converted into the corresponding diethyl-dithioacetals and diethyl-dithioacetal lactones. Using this method only one peak for each compound is obtained, thus providing simple and highly reproducible chromatograms. The analytical procedure was optimised using reference samples of raw plant gums (arabic, karaya, ghatti, guar, locust bean and tragacanth, cherry, plum and peach gums), commercial watercolours and paint layers prepared according to ancient recipes at the Opificio delle Pietre Dure of Florence (Italy). To identify gum media in samples of unknown composition, a decisional schema for the gum identification and the principal component analysis of the relative sugar percentage contents were employed. The procedure was used to study samples collected from wall paintings from Macedonian tombs (4th–3rd centuries bc) and from the Mycenaean “Palace of Nestor” (13th century bc) in Pylos, Greece. The presence of carbohydrates was ascertained and plant gum binders (fruit and a mixture of tragacanth and fruit tree gums) were identified in some of the samples.

Utilization of Partially Methylolated Poly acrylamide Guar Gum in Pigment Printing

Polyacrylamid-guar gum composite has been prepared via graft copolymerization of acrylamide onto guar gum using the KBrO3/ thiourea redox system. The amide groups (40%) in the composite are converted to reactive groups through methylolation with formaldehyde, with a view to obtaining reactive composite. The composite and the reactive composite were used as pastes for printing cotton fabrics with pigment dyes. The prints were assessed for color strength (K/S) and overall fastness properties. Printing was carried out under different conditions, including the amount of composite used as a substitute for kerosene emulsion, the amount of binder incorporated into the printing paste and the types of catalysts. The printed samples were evaluated by monitoring the color strength (K/S) and fastness properties such as washing, rubbing and light. Based on the results obtained, it is concluded that a partial substitution ratio of 20/75 (composite/kerosene emulsion), 8gm binder/100gm printing paste and 1% of catalyst (NH4Cl, DAP, Citric acid or [NH4]2SO4) represent the proper formulation for gaining good dye fixation and excellent fastness properties. The results indicate that the reactive composite prepared is the most suitable thickener for printing cellulosic fabrics with pigment dyes.

Composition and physicochemical properties of locust bean gum extracted from whole seeds by acid or water dehulling pre-treatment

The purpose of this study was to extract locust bean gum (LBG) from whole seeds by two different dehulling pre-treatments. The first process consisted in separating the endosperm (gum) from the hull and the germ after seeds’ pre-treatment with boiling water. The second one used acidic pre-treatment. Then the composition and the physicochemical characteristics of the isolated gum were studied in order to evaluate the effect of extraction process. Comparisons to commercial samples and temperature influence on solubility and rheological properties are included. The yield and quality of Locust bean gum from whole seeds depended on the separation method used. The separation of the seed components by boiling water pre-treatment furnished a higher yield of yellowish endosperm (51–61% w/w), whereas acid dehulling pre-treatment gave an off-white gum yield (37–48% w/w). However, the mannose and galactose content, the solubility, the molecular size and the dynamic viscosity, were higher for LBG from acid dehulling pre-treatment. In addition, a considerable influence of solubilization temperature on macromolecular characteristics and on viscosity properties was noticed.

Produção de goma xantana por fermentação do resíduo de suco de maçã

Goma xantana é um heteropolissacarídeo hidrosolúvel, produzida industrialmente por fermentação da sacarose por Xanthomonas campestris. Suas excelentes propriedades reológicas contribuem para o grande número de aplicações na indústria de alimentos e recuperação terciária de petróleo. Economicamnte a utilização petroquímica não é ainda viável em função do custo da sacarose, o que torna interessante estudar fontes de carbonos alternativas, como é o caso do resíduo do suco de maçã. As cepas de Xanthomonas campestris pv maniothis foram mantidas em agar YM a 4 °C, e o inóculo foi incubado em meio YM. A produção de goma foi realizada nos meios fermentativos I e II, com sacarose como fonte de carbono padrão, e como fonte alternativa o resíduo de maçã fuji. A fermentação em Incubadora/28 °C/150 rpm produziu goma precipitada em álcool. A condição otimizada de 45 g.L-1 de meio II (0,05% uréia, 0,5% de KH2PO4 e 70% de resíduo) representou um rendimento 10 vezes maior do que o obtido com sacarose. Por CG-EM obteve-se 44,53% de manose, 34,76% de glicose e 20,71% de ácido glucurônico para a composição desta goma. O uso de resíduo de maçã para produção de goma xantana é viável porque pode ser usado com um substrato suplementar e apresentar rendimento de goma muito superior ao obtido com sacarose.

Evaluation of mechanical properties of unsaturated polyester-guar gum/hydroxypropyl guar gum composites

Guar gum is a natural polysaccharide that has been explored for various applications. However, there is a limited number of studies in which guar gum has been used as a filler in a polymer. The effect of guar gum and its hydroxypropyl derivatives in unsaturated polyester composites were investigated with respect to their mechanical and chemical properties. The effect of hydroxypropylation and the degree of hydroxypropylation on the properties of resultant composites were also studied. It was observed that the inclusion of guar gum and its derivatives resulted in composites with increased solvent resistance and mechanical properties. An increase in the degree of substitution resulted in increased polymer-filler interac- tion reflected by a positive effect on the mechanical properties of the composites. These results open an avenue for the use of polysaccharides and their derivatives as eco-friendly fillers as a replacement of mineral fillers.

Chemical Composition and Antibacterial Activity of the Essential Oil and the Gum ofPistacia lentiscusVar. chia

The essential oil and gum of Pistacia lentiscus var. chia, commonly known as the mastic tree, are natural antimicrobial agents that have found extensive uses in medicine in recent years. In this work, the chemical composition of mastic oil and gum was studied by GC-MS, and the majority of their components was identified. alpha-Pinene, beta-myrcene, beta-pinene, limonene, and beta-caryophyllene were found to be the major components. The antibacterial activity of 12 components of mastic oil and the oil itself was evaluated using the disk diffusion method. Furthermore, attempts were made to separate the essential oil into different fractions in order to have a better picture of the components responsible for its antibacterial activity. Several trace components that appear to contribute significantly to the antibacterial activity of mastic oil have been identified: verbenone, alpha-terpineol, and linalool. The sensitivity to these compounds was different for different bacteria tested (Escherichia coli, Staphylococcus aureus, and Bacillus subtilis), which suggests that the antibacterial efficacy of mastic oil is due to a number of its components working synergistically. The establishment of a correlation between the antibacterial activity of mastic oil and its components was the main purpose of this research. Mastic gum was also examined, but it proved to be more difficult to handle compared to the essential oil.

Study of water vapour permeability of protein and gum-based edible films by a photothermal method

The water vapour permeability of protein and gum-based edible films was studied by means of a photothermal method. The films were prepared with two basic ingredients, whey protein concentrate and mesquite gum, according to the proportions 75:25, 50:50, 25:75, and 0:100 (weight:weight). The water vapour diffusion coefficient of the analyzed films was found within the interval 0.37 x 10 - 6 to 2.04 x 10 - 6 cm 2 /s, increasing linearly by increasing the mesquite gum composition in the films. The incorporation of mesquite gum in films produces less effective moisture barriers due to its highly hydrophilic property.

Environmental and physiological controls over oxygen and carbon isotope composition of Tasmanian blue gum, Eucalyptus globulus

We measured oxygen isotope ratios (delta18O) of xylem sap, phloem sap, leaves, wood and bark of Eucalyptus globulus Labill. growing in southwestern Australia. Carbon isotope ratios (delta13C) were measured in the dry matter of phloem sap, leaves and wood. Results were used to test several aspects of a mechanistic model of 18O enrichment and provided insights into post-photosynthetic variations in dry matter delta13C. Xylem water delta18O varied little within the tree crown, whereas variation at the landscape-level was more pronounced, with plantations near the coast being enriched by up to 3 per thousand compared with plantations less than 100 km inland. Phloem water was significantly enriched in 18O compared with xylem water in two of three sampling campaigns; mean enrichments were 0.5 and 0.8 per thousand. Phloem sap sugars exported from E. globulus leaves closely reflected observed leaf water enrichment when diurnal variation in photosynthesis was taken into account. Photosynthetic rates were higher in the morning than in the afternoon, whereas leaf water 18O enrichment increased to maximum values in the afternoon. A non-steady-state model of leaf water 18O enrichment accurately predicted observed values through a full diel cycle. Mean estimates of the proportion of organic oxygen effectively exchanging with xylem water during cellulose synthesis were close to 0.40 for both leaves and wood. Carbon isotope ratios of nascent xylem tissues did not differ from those of phloem sap sugars collected concurrently, whereas nascent leaf tissues were depleted in 13C by 2 per thousand compared with phloem sap sugars, suggesting that, in E. globulus, 13C enrichment of sink tissues compared with source leaves does not result from an enriching process within the sink tissue.

Jasmonates are essential factors inducing gummosis in tulips: mode of action of jasmonates focusing on sugar metabolism

The purpose of this study was to know the mechanism of jasmonates to induce gummosis in tulip (Tulipa gesneriana L. cv. Apeldoorn) shoots, especially on the focus of sugar metabolism. Gummosis in the first internode of tulip plants was induced by the application of methyl jasmonate (JA-Me, 1% w/w in lanolin) and jasmonic acid (JA, 1% w/w in lanolin) 5 days after application and strongly stimulated by the simultaneous application of ethylene-releasing compound, ethephon (2-chloroethylphosphonic acid, 1% w/w in lanolin), although ethephon alone had little effect. JA-Me stimulated ethylene production of the first internodes of tulips, ethylene production increasing up to more than 5 times at day 1 and day 3 after the application. On the other hand, application of ethephon did not increase endogenous levels of jasmonates in tulip stems. Analysis of composition of tulip gums revealed that they were consisted of glucuronoarabinoxylan with an average molecular weight of ca. 700 kDa. JA-Me strongly decreased the total amount of soluble sugars in tulip stems even in 1 day after application, being ca. 50% of initial values 5 days after application, but ethephon did not. However, both JA-Me and ethephon had almost no effect on the neutral sugar compositions of soluble sugars mainly consisting of glucose, mannose and xylose in ratio of 20:2:1 and traces of arabinose. Both JA-Me and ethephon applied exogenously stimulated senescence of tulip shoots shown by the loss of chlorophyll. These results strongly suggest that the essential factor of gummosis in tulips is jasmonates affecting the sugar metabolism in tulip shoots. The mode of action of jasmonates to induce gummosis of tulip shoots is discussed in relation to ethylene production, sugar metabolism and senescence.

Flavor Release Measurement from Gum Model System

Flavor release from a mint-flavored chewing gum model system was measured by atmospheric pressure chemical ionization mass spectroscopy (APCI-MS) and sensory time-intensity (TI). A data analysis method for handling the individual curves from both methods is presented. The APCI-MS data are ratio-scaled using the signal from acetone in the breath of subjects. Next, APCI-MS and sensory TI curves are smoothed by low-pass filtering. Principal component analysis of the individual curves is used to display graphically the product differentiation by APCI-MS or TI signals. It is shown that differences in gum composition can be measured by both instrumental and sensory techniques, providing comparable information. The peppermint oil level (0.5-2% w/w) in the gum influenced both the retronasal concentration and the perceived peppermint flavor. The sweeteners' (sorbitol or xylitol) effect is less apparent. Sensory adaptation and sensitivity differences of human perception versus APCI-MS detection might explain the divergence between the two dynamic measurement methods.

Cationic composition and the tannin content of five gums from Venezuelan Mimosaceae species

The growing interest in polysaccharides from source others than Acacia senegal has fostered research on polysaccharides from Venezuelan Mimosaceae spp. An analytical determination of cationic composition and polyphenol and tannin contents have been made of gum specimens from Acacia macracantha, Acacia tortuosa, Acacia glomerosa, Enterolobium cyclocarpum and Samanea saman. Calcium, potassium, magnesium and sodium were the four major components of the ash composition of these Mimosaceae gums. In addition to these data, chromium, lead and vanadium were not detected at limit of detection (1 ppm) in any of the samples. The total tannin contents are comparable to other Acacia gums but the value of A. glomerosa is very low. Condensed tannins are very low in all the gum samples studied. This parameter, has not, to date, been reported for any gum. The results suggest that A. glomerosa may be useful for the food industry while the other studied gums may have some technological application.

Viscosity of solutions of xanthan/locust bean gum mixtures

Xanthan and locust bean gums are polysaccharides able to produce aqueous solutions with high viscosity and non-Newtonian behaviour. When these solutions are mixed a dramatic increase on viscosity is observed, much greater than the combined viscosity of the separated polysaccharide solutions. In this work the influences of different variables on the viscosity of solutions of mixtures of xanthan/locust bean gum have been studied. Total polysaccharide concentration, xanthan and locust bean ratio on mixture and temperature at which the gum was dissolved (dissolution temperature) for both xanthan and locust bean gums have been considered. Under these different operational mixture conditions shear rate and time have also been considered to describe the rheological behaviour of the solutions studied. The high viscosity increase observed in these mixtures is due to the interaction between xanthan gum and locust bean gum molecules. This interaction takes place between the side chains of xanthan and the backbone of the locust bean gum. Both xanthan molecule conformation in solution – tertiary structure – and locust bean gum structure show great influence on the final viscosity of the solution mixtures. Xanthan conformation changes with temperature, going from ordered structures to disordered or chaotic ones. Locust bean gum composition changes with dissolution temperature, showing a dissolved galactose/mannose ratio reduction when temperature increases, ie the smooth regions – zones without galactose radicals – are predominantly dissolved. The highest viscosity was obtained for the solution mixture with a total polysaccharide concentration of 1.5 kg m−3 and a xanthan/locust ratio of 2:4 (w/w) and when xanthan gum and locust bean gum were dissolved at 40°C and 80°C, respectively. © 1999 Society of Chemical Industry

Non-stick chewing gum

A non-stick, chewing gum base composition which is free from fats, waxes, and elastomer solvent resins, and a non-stick chewing gum composition made from the gum base. The resulting chewing gum is easily removable from a variety of surfaces.

Composition and rheological properties of cashew tree gum, the exudate polysaccharide from Anacardium occidentale L

Anacardium occidentale gum from Brazilian plants has a higher galactose content and lower arabinose and rhamnose content than those gums from India and Papua. The other constituents (glucose, mannose and glucuronic acid) are similarly distributed. GPC of cashew gum detected the presence of 6% poly-saccharide-protein complex, 42% polysaccharide of M pk 1.6 × 10 4. The whole gum is a low viscosity polysaccharide with an activation energy of flow for solution at 2 and 3% ( 1 ̃ 6 kJ mol −1), characteristic of systems with little intra and intermolecular interactions. Experiments on the effects of NaCl, CaCl 2 and AlCl 3 on the reduced viscosity, as well as the effect of salt concentration on the specific viscosity, indicated that the affinity between A. occidentale gum and metal ions follows the order: Al 3 > Ca 2+ > Na +.

Fractionation and characterization of gum arabic samples from various African countries

Four gum arabic samples obtained from various African countries (Sudan, Chad and Senegal) were separated into three or four fractions by hydrophobic interaction chromatography on Phenyl Sepharose CL-4B. The molecular mass distribution of the fractions was monitored using gel permeation chromatography on a Superose 6 column and indicated that each was polydisperse confirming the extreme heterogeneous nature of the gum. The fractions were characterized using various chemical and physicochemical techniques. For all four gum samples the major fraction which represented >90 wt% of the total yield was found to be low in protein (<2%). The other minor fractions (~10 wt% of the total) were found to have higher proportions of protein (~10–60%). Despite the differences in their geographical origin, the molecular mass distribution, specific rotation and sugar composition of the parent gums and their equivalent fractions did not differ significantly.

CHARACTERIZATION OF SEDIMENTS AND ADHERENT GUM FROM CRACKED MIDDLE DISTILLATES

ABSTRACT ABSTRACT The composition of insoluble sediments and adherent gum obtained from ambient and accelerated oxidation stability tests of different cracked middle distillates (LCO, TCO & Coker Kerosene) were studied using FTIR Spectroscopy. The sediment & gum formed in these fuels after extraction with methanol were also characterized. The differences in the composition of insoluble sediment & adherent gum obtained under different conditions have been observed.