Type Of Gum Research Articles

Flavor-Enhanced Modulation of Cerebral Blood Flow during Gum Chewing.

BackgroundFlavor perception, the integration of taste and odor, is a critical factor in eating behavior. It remains unclear how such sensory signals influence the human brain systems that execute the eating behavior.MethodsWe tested cerebral blood flow (CBF) in the frontal lobes bilaterally while subjects chewed three types of gum with different combinations of taste and odor: no taste/no odor gum (C-gum), sweet taste/no odor gum (T-gum), and sweet taste/lemon odor gum (TO-gum). Simultaneous recordings of transcranial Doppler ultrasound (TCD) and near infrared spectrometer (NIRS) were used to measure CBF during gum chewing in 25 healthy volunteers. Bilateral masseter muscle activity was also monitored.ResultsWe found that subjects could discriminate the type of gum without prior information. Subjects rated the TO-gum as the most flavorful gum and the C-gum as the least flavorful. Analysis of masseter muscle activity indicated that masticatory motor output during gum chewing was not affected by taste and odor. The TCD/NIRS measurements revealed significantly higher hemodynamic signals when subjects chewed the TO-gum compared to when they chewed the C-gum and T-gum.ConclusionsThese data suggest that taste and odor can influence brain activation during chewing in sensory, cognitive, and motivational processes rather than in motor control.

In situ effect of chewing gum containing CPP–ACP on the mineral precipitation of eroded bovine enamel—A surface hardness analysis

ObjectivesStimulation of salivary flow is considered a preventive strategy for dental erosion. Alternatively, products containing calcium phosphate, such as a complex of casein phosphopeptide–amorphous calcium phosphate (CPP–ACP), have also been tested against dental erosion. Therefore, this in situ study analyzed the effect of chewing gum containing CPP–ACP on the mineral precipitation of initial bovine enamel erosion lesions. MethodsTwelve healthy adult subjects wore palatal appliances with two eroded bovine enamel samples. The erosion lesions were produced by immersion in 0.1% citric acid (pH 2.5) for 7min. During three experimental crossover in situ phases (1 day each), the subjects chewed a type of gum, 3 times for 30min, in each phase: with CPP–ACP (trident total), without CPP–ACP (trident), and no chewing gum (control). The Knoop surface microhardness was measured at baseline, after erosion in vitro and the mineral precipitation in situ. The differences in the degree of mineral precipitation were analyzed using repeated measures (RM-) ANOVA and post hoc Tukey's test (p<0.05). ResultsSignificant differences were found among the remineralizing treatments (p<0.0001). Chewing gum (19% of microhardness recovery) improved the mineral precipitation compared to control (10%) and the addition of CPP–ACP into the gum promoted the best mineral precipitation effect (30%). ConclusionsUnder this protocol, CPP–ACP chewing gum improved the mineral precipitation of eroded enamel. Clinical significanceSince the prevalence of dental erosion is steadily increasing, CPP–ACP chewing gum might be an important strategy to reduce the progression of initial erosion lesions.

Effect of gum tragacanth on rheological and physical properties of a flavored milk drink made with date syrup

Date syrup as a nutritional additive and safe alternative to added sugar is one of the best choices for milk flavoring. In this study, a flavored milk beverage was formulated using date syrup for flavoring the product and gum tragacanth to obtain an acceptable mouth feel. Steady shear and dynamic oscillatory rheological properties of the samples contained 3 concentrations (0, 0.1, 0.2, and 0.3%, wt/wt) of 2 types of gum tragacanth (Astragalus gossypinus and Astragalus rahensis) which at 3°C, were studied. Particle size distribution and colorimetric assays were determined by laser diffractometry and using reflection spectrometer, respectively. Sensory analysis was performed with 25 semitrained panelists, using a 5-point hedonic scale. The results showed that viscoelastic properties, flow behavior parameters, particle size, and color parameters (L*, a*, and b*, where L* represents lightness, a* represents the redness/greenness quality of the color, and b* represents the yellowness and blueness quality of the colors) were significantly affected by the concentration of the gum tragacanth and the severity of this effect was influenced by the type of gum. The use of appropriate type and concentration of gum tragacanth in date milk formulation can improve the texture and mouth feel by affecting on particle size and the flow behavior of this product.

Microbead design for sustained drug release using four natural gums

Four natural gums, namely albizia, cissus, irvingia and khaya gums have been characterized and evaluated as polymers for the formulation of microbeads for controlled delivery of diclofenac sodium. The natural gums were characterized for their material properties using standard methods. Diclofenac microbeads were prepared by ionotropic gelation using gel blends of the natural gums and sodium alginate at different ratios and zinc chloride solution (10%w/v) as the crosslinking agent. The microbeads were assessed using SEM, swelling characteristics, drug entrapment efficiencies and release properties. Data obtained from in vitro dissolution studies were fitted to various kinetic equations to determine the kinetics and mechanisms of drug release, and the similarity factor, f2, was used to compare the different formulations. The results showed that the natural gum polymers varied considerably in their material properties. Spherical and discrete microbeads with particle size of 1.48–2.41μm were obtained with entrapment efficiencies of 44.0–71.3%w/w. Drug release was found to depend on the type and concentration of polymer gum used with formulations containing gum:alginate ratio of 3:1 showing the highest dissolution times. Controlled release of diclofenac was obtained over for 5h. Drug release from the beads containing the polymer blends of the four gums and sodium alginate fitted the Korsmeyer–Peppas model which appeared to be dependent on the nature of natural gum in the polymer blend while the beads containing alginate alone fitted the Hopfenberg model. Beads containing albizia and cissus had comparable release profiles to those containing khaya (f2>50). The results suggest that the natural gums could be potentially useful for the formulation controlled release microbeads.

Distribution, habitat preferences and management of the yellow-bellied glider, Petaurus australis, on the Bago Plateau, New South Wales: a reassessment of the population and its status

Context A population of yellow-bellied glider on the Bago Plateau, near Tumbarumba, was listed as an Endangered Population in 2008 under the New South Wales (NSW) Threatened Species Conservation Act 1995. The listing was based on limited data that suggested that the population is geographically and genetically distinct and its habitat in decline. Aims To review the validity of the endangered-population listing following the collection of new data on its distribution, habitat preferences and responses to logging. Methods Surveys for the yellow-bellied glider were conducted at a subset of sites established in 1995 on the Bago Plateau as well as across parts of the neighbouring Kosciuszko National Park, which had not been surveyed previously. The distribution of suitable habitat throughout these areas was evaluated. Key results The yellow-bellied glider was recorded at 29% of 48 sites resurveyed in 2010, 54% of which were previously occupied in 1995. Most changes in glider occupancy occurred at sites that had not been logged during the intervening period. The gliders preferred forest types dominated by montane gums (Eucalyptus dalrympleana, E. viminalis, E. camphora, E. pauciflora and E. stellulata) and used forest types of montane gums mixed with E. robertsonii or E. delegatensis in proportion to their availability across the landscape. The gliders were not observed to use monospecific stands of E. delegatensis. The yellow-bellied glider was also recorded frequently in Kosciuszko National Park. E. dalrympleana was consistently represented in the distribution of this species across the NSW Snowy Mountains. Conclusions Yellow-bellied glider site occupancy was not related to timber harvesting. Its habitat was not restricted by elevation or confined within Bago and Maragle State Forests by the Tumut River Gorge, Blowering and Talbingo Dams, as previously thought. We estimated that there is a large population of the gliders occupying up to 440 000 ha of contiguous habitat across the broader Snowy Mountains region of NSW, extending also into ACT and Victoria. Implications The listing of the Bago Plateau portion of this population as an endangered population appears inconsistent with relevant listing criteria and requires review.

Design, formulation and evaluation of caffeine chewing gum.

Background:Caffeine which exists in drinks such as coffee as well as in drug dosage forms in the global market is among the materials that increase alertness and decrease fatigue. Compared to other forms of caffeine, caffeine gum can create faster and more prominent effects. In this study, the main goal is to design a new formulation of caffeine gum with desirable taste and assess its physicochemical properties.Materials and Methods:Caffeine gum was prepared by softening of gum bases and then mixing with other formulation ingredients. To decrease the bitterness of caffeine, sugar, aspartame, liquid glucose, sorbitol, manitol, xylitol, and various flavors were used. Caffeine release from gum base was investigated by mechanical chewing set. Content uniformity test was also performed on the gums. The gums were evaluated in terms of organoleptic properties by the Latin-Square design at different stages.Results:After making 22 formulations of caffeine gums, F11 from 20 mg caffeine gums and F22 from 50 mg caffeine gums were chosen as the best formulation in organoleptic properties. Both types of gum released about 90% of their own drug content after 30 min. Drug content of 20 and 50 mg caffeine gum was about 18.2-21.3 mg and 45.7-53.6 mg respectively.Conclusion:In this study, 20 and 50 mg caffeine gums with suitable and desirable properties (i.e., good taste and satisfactory release) were formulated. The best flavor for caffeine gum was cinnamon. Both kinds of 20 and 50 mg gums succeeded in content uniformity test.

Steady and Dynamic Shear Rheological Properties of Gum-Based Food Thickeners Used for Diet Modification of Patients with Dysphagia: Effect of Concentration

Gum-based food thickeners are widely used for diet modification for patients with dysphagia in Korea. In this study, the rheological properties of two commercially available gum-based food thickeners (xanthan gum and xanthan-guar gum mixture) marketed in Korea were determined as a function of concentration. The steady and dynamic shear rheological properties of the food thickeners in water were investigated at five different concentrations (1.0%, 1.5%, 2.0%, 2.5%, and 3.0% w/w). Both food thickeners showed high shear-thinning fluid characteristics (n=0.14-0.19) at all concentrations (1.0-3.0%). In general, the thickener with the xanthan-guar gum mixture showed higher values for steady shear viscosity compared to that with xanthan alone, whereas it showed lower dynamic rheological parameter values. Steady and dynamic rheological parameters demonstrated differences in rheological behaviors between the gum-based food thickeners, indicating that their rheological properties are related to the type of gum and gum concentration. In particular, the type of gum played a role in the time-dependent flow properties of the gum-based food thickeners. Appropriately selecting a commercial food thickener appears to be of great importance for dysphagia therapists and patients.

Influence of several gums on the growth and the production of a bacteriocin like substance from Lactobacillus curvatus/sakei ACU-1

The study was meant to evaluate the influence of xanthan gum, λ-carrageenan, arabic gum and tragacanth gum on the growth and in situ production of bacteriocin like inhibitory substances from Lactobacillus curvatus/sakei ACU-1. Listeria innocua ATCC 33090 and Staphylococcus aureus FBUNT were used as indicator microorganisms. The growth of, and bacteriocin production by, Lactobacillus sakei/curvatus ACU-1 strain was assessed using MRS broth supplemented with 0.5 g/100 ml of each gum. Results showed that xanthan and arabic gum did not significantly influence bacterial growth rate while tragacanth and λ-carrageenan promoted it. The effect of the presence of gums on bacteriocin production was dependent upon the type of gum, i.e. compared to the control system, arabic gum diminished it, and the rest of the gums showed an enhancing effect. Arabic gum interfered with bacteriocin activity and thus its use in food products would be conditioned.

An Experimental Study of Systematic Errors in ADC-Based Instruments

The paper discusses the problem of quantifying the contribution of systematic errors on the overall measurement uncertainty. We promote the experimental evaluation of uncertainty due to systematic errors. The method is alternative to non-experimental approaches, including the GUM one. The uncertainty due to systematic errors in ADC-based instruments is addressed.We present a general scheme, and use it for the uncertainty due to ADC gain error. The GUM type B uncertainty seems quite poor, compared to the experimental uncertainty.

Evaluation of Analgesic, Antidiarrhoeal and Cytotoxic Activities of Ethanolic Extract of Bacopa monnieri (L)

Aims: The crude ethanolic leaf extract of Bacopa monnieri (L) Penn. (family: Scrophulariaceae) was evaluated for its possible phytochemical nature (group determination of plant constituent) and selected pharmacological activities (analgesic, antidiarrhoeal and cytotoxic activity) growing in Bangladesh. Methodology: The antinociceptive activity was evaluated by acetic acid induced writhing model, antidiarrhoeal activity by castor oil induced diarrheal method and cytotoxicity by brine shrimp lethality bioassay. Results: Phytochemical analysis of the ethanolic extract of B. monnieri indicated the presence of reducing sugar, tannins, steroid, alkaloid, saponin and gum types of compounds. The ethanolic extract of B. monnieri has effect on acetic acid induced writhing in mice. At the dose of 250 mg/kg and 500 mg/kg of body weight, the extract produced 36.69% and 59.17% writhing inhibition in test animals respectively. The results were statistically significant (p &lt;0.01 and p &lt;0.001) and was comparable to the standard drug Diclofenac Na, which showed 72.78% at a dose of 25 mg/kg weight. The ethanolic extract of B. monnieri has effect on castor oil induced diarrhea in mice. The result showed that the extract decreased the mean number of defecation which were 35.42 % and 47.92 % (p &lt;0.001) at the doses of 250mg/kg and 500mg/kg respectively. The latent period for the extract treated group was increased (p &lt;0.01) as compared to control group. The ethanolic of extract of B. monnieri showed significant toxicity to the brine shrimp nauplii. The concentrations of crude extract for 50% mortality (LC50) and 90% mortality (LC90) were 40 μg/mL and 150 μg/mL respectively. Conclusion: Therefore, the obtained results tend to suggest the antinociceptive, antidiarrhoeal and cytotoxic activities of crude ethanolic extract of Bacopa monnieri leaves and thus provide the scientific basis for the traditional uses of this plant part as a remedy for pain and diarrhoea.

Physicochemical characteristic of unstimulated and stimulated saliva with different chewing gum stimulation

stimulate salivary flow, increase in saliva flow lead to more frequent replenishment and greater supply of antibacterial factors, saline, buffers, minerals and other beneficial constituents, increase pH and buffer capacity of whole saliva. The aim of the present study was to investigate the effect of different chewing gums on the salivary constituents including some elements (Magnesium, Calcium, Copper and Zinc)(chemical),PH and flow rate(physical)characteristic. Materials and Methods: Saliva samples was collected from dental students/college of dentistry 23 age stimulated by three types of chewing gum (mastic, Arabic, sugar) and control group (unstimulated saliva), pH and saliva flow rate was recorded for four groups. Biochemical analysis was assessed for some salivary elements, (Magnesium, Calcium, Copper, and Zinc) and its relation with different chewing gum and control group. Student's t-test, ANOVA and LSD test was used for statistical analysis. Also mean and standard deviation was recorded. Results: Mean value of pH was found to be high in three types of chewing gum with highly significant difference comparing with control group. A significant difference in flow rate was found between control and sugared gum group. Mg and Ca ione was found to be highly significant between mastic gum group and other three groups , as well as highly significant difference was recorded among four groups of saliva in Cu ione, while no significant difference was showed between Zn ione and four groups. Conclusion: Chewing gum include natural (mastic and Arabic) and sugared was increases salivary pH. Use of chewing gum especially mastic and Arabic can enhance the remineralizing potential of the mouth, probably by stimulating salivary flow which may lead to rise salivary elements.

Development of natural gum based fast disintegrating tablets of glipizide

Dysphagia and risk of choking are leading causes of patient non‐compliance in the self‐administration of conventional tablets.To overcome these limitations of conventional tablets fast‐disintegrating tablets were developed, using natural gums.Natural gums were evaluated for bulk swelling capacity. Powder mix containing natural gums and glipizide was evaluated for water sorption, swelling index and capillary action. For faster onset and immediate hypoglycemic action, the fast disintegrating tablets were prepared with various types of natural gums using the direct compression technique. Formulations containing guar gum disintegrated within a minute and fulfilled the official requirements for dispersible tablets. As the amount of guar gum increased, the friability increased and hardness decreased, resulting in a shorter wetting and disintegration time. Gum acacia and gum tragacanth did the opposite.The glipizide‐loaded fast disintegrating tablet prepared with 18 mg of guar gum gave a friability of 0.46 ± 0.02%, content uniformity of 99.34 ± 0.82%, drug content of 99.15 ± 1.16%, wetting time of 39.0 ± 1.04 sec, hardness of 5.70 ± 1.41 Kg and disintegration time less than 30 sec, suggesting that it was a practical product with a good tablet property. In conclusion, natural gum based patient‐friendly fast disintegrating tablets of glipizide can be successfully formulated.

Comparison of the effects of gums on dynamic rheological properties of acetylated sweet potato starch

Dynamic rheological properties of acetylated sweet potato starch (ASPS) pastes mixed with 3 commercial gums (guar gum, locust bean gum, and xanthan gum) were investigated at different gum concentrations. The dynamic moduli of the ASPS-gum mixtures were higher than those of the control, and they increased with an increase in gum concentration. In particular, the G′ value of xanthan and G″ value of guar gum at a 0.6% gum concentration were much higher as compared to those of other mixtures. Tan δ values of ASPS-xanthan mixtures were much lower than those of other samples, indicating that the elastic properties in the ASPS-gum mixture systems were strongly affected by the additions of xanthan. These results suggest that the presence of gums in ASPS modifies the viscoelastic properties, and that these modifications are dependent on the gum type and gum concentration.

INFLUENCE OF CHEWING GUM ON THE DISCRIMINATION EFFICIENCY OF 2AFC SENSORY TESTS

ABSTRACTA water‐based sucrose solution at subthreshold concentration (1 g/L) and pure water were used to evaluate the discriminative ability of nontrained judges to perform a two‐alternative forced‐choice (2AFC) test after the use of chewing gum for different periods of time. Three types of chewing gum were evaluated: CF, fruit‐flavored caloric (sweetened with sucrose/dextrose); NF, fruit‐flavored noncaloric (sweetened with Sorbitol/Xylitol); and NC, unsweetened, unflavored, unsoftened gum base. Two fixed times and four time classes were selected for the chewing times studied at 2, 5, 10–19, 20–29, 30–39 and ≥40 min. While the control group (no gum) was not able to consistently identify the sweet solution, judges chewing NC, NF and CF were able to do so (α = 0.05) after 5, 10 and 30 min of chewing, respectively. An increase in salivary flow rate, salivary pH and perceptive memory elicited by the gustatory and mechanical stimulation involved in the act of chewing are suggested as possible mechanisms behind the observed effect.PRACTICAL APPLICATIONSDiscriminative sensory analytical methods must be able to reliably detect and quantify differences between samples. Any new test protocol or addition to it, which is able to improve the performance and sensitivity of sensory judges as individuals or as a group, helps in reaching this goal. From a practical point of view, ensuring that a test protocol renders results comparable with those produced by the most sensitive individuals in a given population guarantees the validity and usefulness of the conducted tests and their results. The proposed use of chewing gum as a preparative step in discriminative sensory test protocols is an attempt to finding a method able to increase the discriminative ability of sensory taste panels composed of nontrained judges.

Rheological behavior and stability of d-limonene emulsions made by a novel hydrocolloid (Angum gum) compared with Arabic gum

Our goal was to evaluate emulsion stability, droplet size analysis and rheological behavior of the emulsions prepared by a native biopolymer namely Angum gum (An) compared with Arabic gum (Ar) stabilized emulsions. After gum extraction, gum dispersions with maltodextrin were prepared in water (in 1–5% concentrations) and emulsified with 5% and 10% d-limonene using high pressure homogenization. Statistical analysis revealed a significant influence of gum type and gum concentration on emulsion stability at α=0.05. Flavor level was not important statistically in emulsion stability but it was the only factor with a significant influence (P<0.05) on surface tension of the emulsions. The results showed that Angum gum was superior to Arabic gum in stabilizing emulsions during storage. Also, rheological data revealed that Angum gum-emulsions’ behavior was following the Herschel–Bulkley model with higher viscosities compared to Arabic gum emulsions, which could be the main reason of higher emulsion stabilities with this novel hydrocolloid.

Avaliação do bis(4-metilfenilditiocarbimato)zincato(II) de tetrabutilamônio como acelerador no processo de vulcanização do elastômero polibutadieno

O ZNIBU, acelerador de caráter lento foi avaliado neste trabalho em composições de polibutadieno. Este acelerador foi sintetizado com o objetivo de substituir, ou reduzir, o uso de alguns aceleradores comerciais muito utilizados em composições elastoméricas mas que, por serem formadores de nitrosaminas, podem ser prejudiciais à saúde. A fim de corrigir o caráter de acelerador lento do ZNIBU, este composto foi utilizado em conjunto com o acelerador comercial CBS (N-ciclohexil-2-benzotiazol-2-sulfenamida). Foi observado que pequenas quantidades dos dois aceleradores não são efetivas na aceleração da vulcanização nas composições do tipo goma pura. No entanto a presença de negro de fumo exerce um efeito positivo sobre a velocidade. As propriedades mecânicas estudadas mostram que o ZNIBU aumenta a resistência à tração da goma pura (35%), em comparação com a composição similar vulcanizada com CBS e, na presença do negro de fumo, este aumento é ainda mais expressivo (175%). Quanto à resistência ao rasgamento, a vulcanização com o ZNIBU forneceu o mais baixo valor da propriedade para a goma pura, enquanto que a composição com negro de fumo apresentou o mais alto valor.

Introduction of gum Arabic and guar to the diet of captive black-tufted ear marmosets

Gum plays a significant role in the feeding ecology of wild callitrichids and thus is also supplemented to several primate species in captivity. However, little is known about the feeding habits of black tufted-ear marmosets (including gummivory), in both wild and captive populations. Therefore, the present study introduced gum to the diet of adult captive black tufted-ear marmosets ( Callithrix penicillata), analyzing the influence of gum type (Arabic vs. guar), solution level (50, 25 or 15% m/m gum:water) and time of provision (morning vs. afternoon). Gum intake, latency to first consumption, foraging time/frequency and inter-foraging interval were assessed, as well as changes in body weight. Marmosets were pair-tested in their home-cages and randomly divided into three groups ( n = 6): control (water), gum Arabic or gum guar. Water/gum solution was given twice a day (07:30 to 08:30 and 15:00 to 16:00 h), three times a week, during 3 weeks. Each pair was thus submitted to eighteen 30-min trials, with each gum solution being evaluated on three separate occasions during the morning and afternoon periods. Latency to first consumption and foraging were observed only during the first 5-min of each trial. Although water-solubilized gum was promptly consumed, marmosets preferred the Arabic version, with a significantly higher ( P < 0.01) and more efficient intake (i.e., greater foraging time/frequency and shorter inter-foraging intervals). Preference was most pronounced for solutions with greater gum content (i.e., 50%). Latency to first consumption (mean ± SEM range: 39 ± 21 to 94 ± 19 s) and body weight (mean ± SEM range: 318 ± 27 to 385 ± 11 g) did not differ within or between groups, and time of provision (morning vs. afternoon) did not influence the results. Intake and foraging were not recorded for the water-treated marmosets. Thus, gum is a viable dietary supplement for captive black tufted-ear marmosets, with attention needed on the type of gum provided, as well as its preparation (solubilization).

Effect of gamma irradiation on rheological properties of polysaccharides exuded by A. fluccosus and A. gossypinus

In this study, Iranian gum tragacanth (GT) exudates from Astragalus fluccosus (AFG) and Astragalus gossypinus (AGG) were irradiated at 3, 7, 10 and 15kGy. Fourier transform infrared spectroscopy (FTIR) data showed that irradiation did not induce changes in the chemical structure of either type of gum. Although particle size distribution and both steady shear and dynamic rheological properties were considerably affected by the irradiation process, the magnitude of the effect of irradiation on each of the rheological and size variables was different for the hydrocolloids. For instance, for AGG, increasing the irradiation dose from 3 to 10kGy, the d(0.5) and D[3,2] values were reduced by one-sixth to one-eighth fold. Colour measurement revealed that the radiation process led to an increase in the yellow index and b* values for both types of GT in powder form, but it was more pronounced for AGG samples. Irradiation led to an approximate 13-fold increase in redness in AFG. Surface and shape changes of the gum crystals were studied by scanning electron microscope (SEM) and a smoother surface for irradiated samples was detected. The notable changes in functional properties of each variety of irradiated gum should be taken into consideration before using the radiation technology as a commercial tool for sterilisation.

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. 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.

Rheological and thermal effects of galactomannan addition to acorn starch paste

Effect of galactomannans (guar gum and locust bean gum) at different concentrations on rheological and thermal properties of acorn starch pastes was examined. Steady and dynamic shear rheological tests indicated that the magnitudes of consistency index (K), apparent viscosity (η a,100), Casson yield stress (σ oc), dynamic moduli ( G′, G″), and complex viscosity (η∗) of acorn starch-galactomannan mixtures were much higher than those of the control (0 g/100 g gum concentration), and that these values also increased with an increase in gum concentration. At temperatures ranging from 25 to 70 °C, the effect of temperature on η a,100 was well described by the Arrhenius equation. In addition, DSC studies showed that the presence of galactomannans resulted in an increase in the transition temperatures (T o, T p, and T c) and a decrease of the gelatinization enthalpy (ΔH). In general, these results suggest that the presence of galactomannans in acorn starch modifies the rheological and thermal properties, but that these modifications are dependent on the gum type and gum concentration.