Classification and physicochemical characterization of mesquite gum (Prosopis spp.)

Under environmental stress conditions, mesquite trees can excrete a proteinaceous arabinogalactan gum that is similar to gum arabic. Given the application potential of this type of gums a classification procedure for the mesquite gum is proposed. The main physicochemical properties of the best-quality mesquite gum were determined and compared with those of gum arabic. Additionally, the composition and molecular changes induced by purification processes were recorded. One batch (157 kg) of mesquite gum was categorized by subjective assessment into three classes (MGA, MGB and MGC) from high- to low-quality. Approximately 17.5% was classified as top-quality gum. It was found that this class of mesquite gum has lower humidity, inorganic and tannins content than the other classes, or even than the gum arabic sample used as a reference. All of the mesquite gum classes have higher protein content and lower intrinsic viscosity than gum arabic. The purification processes were shown to reduce the content of lower molecular weight compounds that modify the interface properties of the gum. The results indicate that the proposed classification method can be used to select mesquite gum with physicochemical properties comparable to those of commercial gum arabic.     

Crossflow microfiltration of gum arabic solutions: Comparison of the classical system with the co-current permeate flow system

Gum arabic is a natural gum exuded mainly by the trees Acacia senegal , currently used in the food industries for its emulsifying, thickening and stabilizing properties. Its present processing includes various operations providing a quite turbid product. Crossflow microfiltration could be interesting for the clarification and the cold-pasteurization of the gum arabic solutions. Several experiments were therefore made with the crossflow microfiltration unit at ENSIA, using two different systems: the classical one (without permeate circulation), and the co-current permeate flow system (CCPF) allowing the exploration of the low transmembrane pressures range. With gum arabic solutions of 0.17g solids g⁻¹ solution and 70°C, the best results after 60 min of filtration (105.7 L h⁻¹ m⁻², 4.4% of solids retention and 83.4% of clarification) were obtained with the CCPF system at low transmembrane pressure and high crossflow velocity (0.3 bar and 7.5ms⁻¹).     

Effects of batters containing different gum types on the quality of deep‐fat fried chicken nuggets

The effects of various gum types [hydroxypropylmethylcellulose (HPMC), guar gum, xanthan gum, gum arabic] on the quality of deep‐fat fried chicken nuggets were studied. Chicken samples, 0.04 m in diameter and 0.015 m in thickness taken from the breast portion, were coated with batters composed of a 3:5 solid to water ratio by immersion. The solid content of batter formulations contained equal amounts of corn and wheat flours, 1.0% gum, 1.0% salt and 0.5% leavening agent. As control, batter without gum addition was used. Samples were fried at 180 °C for 3, 6, 9 and 12 min. The hardness and oil content of the chicken nuggets increased whereas the moisture content decreased during frying. HPMC and xanthan gums reduced oil absorption significantly compared with other gums and the control. When gum arabic was added to the batter formulation, a product with the highest oil content and porosity was obtained. Copyright © 2005 Society of Chemical Industry     

Development of a simple model based on chemical kinetics parameters for predicting respiration rate of carambola fruit

The respiration model was parameterised with experimental data obtained at temperatures 10, 15, 20, 25 and 30 °C by the closed system. Reaction orders of O₂ and CO₂ determined for respiration rate are 0.912 and −0.24, respectively. Estimates of A and E _a for rate coefficient are 5.219 _× 10¹⁰ h⁻¹ and 61.397 kJ mol⁻¹, respectively. The reliability of the model was verified against new data generated from 18 °C. An enzyme kinetics based model was likewise built and verified as a contrast. Verification results indicate that the chemical kinetics model performs very well and has superiority over the enzyme kinetics one. This study demonstrates that chemical kinetics can be used to underpin the development of simple respiration model and should facilitate the prediction of respiration rate for the carambola fruit in practice.     

The rheological properties of ketchup as a function of different hydrocolloids and temperature

The flow properties of ketchup were assessed upon addition of commonly used food thickeners: guar, xanthan and CMC gum at three different concentrations (0.5%, 0.75% and 1%) and four temperatures (25, 35, 45 and 55 °C). The ketchup without supplementation served as a control. All ketchup formulations exhibited non-Newtonian, pseudoplastic behaviour at all temperatures and hydrocolloid levels. The Power-law and Herschel-Buckley model were successfully applied to fit the shear stress versus shear rate data. The flow behaviour indices, n and n' , varied in the range of 0.189–0.228 and 0.216–0.263, respectively. The consistency coefficients, k and k' , were in the range of 8.42–27.22 and 6.56–20.10 Pa s ⁿ , respectively. The addition of hydrocolloids increased the yield point (τ₀) and apparent viscosity of the ketchup in comparison to that of the control. The Arrhenius equation was successfully used to describe the effects of temperature on the apparent viscosity of the prepared formulations. The E _a value appeared in the range between 5492.6 and 21475.8 J mol⁻¹.     

Firmness, seed wholeness and water uptake during the cooking of lentils (Lens culinaris cv. anicia) for 'sous vide' and catering preparations

The study aimed to optimize cooking conditions of lentils ( Lens culinaris cv. anicia ) for 'sous vide' processing and catering. the softening rate of lentil seeds during cooking in deionized water was consistent with two simultaneous first order mechanisms. the apparent activation energies of firmness breakdown and loss of integrity were 86.5 kJ mol⁻¹ and 271.3 kJ mol⁻¹, respectively. Wholeness of the lentils was better preserved when the cooking temperature did not exceed 90°C. the loss of firmness was a consequence of hydration of the seed since the regression coefficient between the logarithm of residual firmness and water uptake reached −0.93 regardless of cooking temperature and heating medium (steam or water). Thus, lentil seeds maintained their firmness and wholeness as required for 'sous vide' and catering if they were cooked below 90°C for up to 2 h. Higher temperature or longer cooking time resulted in loss of firmness and wholeness.     

RHEOLOGICAL PROPERTIES AND APPLICATIONS OF MESQUITE TREE (PROSOPIS JULIFLORA) GUM. 1. RHEOLOGICAL PROPERTIES OF AQUEOUS MESQUITE GUM SOLUTIONS

The viscosities of aqueous mesquite gum solutions were measured at gum concentrations extending to 16.7% (w/v). Very dilute solutions exhibited typical polyelectrolyte behavior with respect to the influence of gum concentration on the reduced viscosity in the absence and presence of electrolyte. Shear thickening was exhibited at concentrations of 1–16.67% (w/v) when the shear rate exceeded ∼100 s⁻¹, whereas shear thinning was exhibited at lower shear rates. Shear thickening was attributed to configurational changes in the gum molecules at high shear rates. Electrolytes (0.1N NaCl and 0.1N CaCl₂) reduced the viscosity of concentrated solutions at high shear rates to a larger extent than increasing the pH. Charge screening by electrolyte permits the gum molecules to assume a more compact configuration.     

Desulfiting Dried Apricots by Hydrogen Peroxide

ABSTRACT: Removal of sulfites from excessively sulfited dried apricots using hydrogen peroxide (H₂O₂) was studied. Dried apricots were dipped into 0.5, 1.0, and 1.5% H₂O₂ solutions at 20 °C and 40 °C for various times. At 60 °C, apricots were also treated with 1% H₂O₂ solution. Removal of sulfites by H₂O₂ followed a 1st-order kinetic model. At 20 °C to 60 °C and 1% H₂O₂ concentration, the E_a value was 22.46 kJ mol⁻¹. H₂O₂ treatment caused lighter, more yellow, and less red dried apricots. Critical factors for H₂O₂ application are choosing the appropriate H₂O₂ concentration, temperature, and exposure time and without bleaching the natural color of dried apricots.     

Hydrocolloids with emulsifying capacity. Part 1 – Emulsifying properties and interfacial characteristics of conventional (Acacia senegal (L.) Willd. var. senegal) and matured (Acacia (sen) SUPER GUM™) Acacia senegal

The emulsifying properties and interfacial behaviour of conventional arabic gum (Acacia Senegal, control gum) and after thermal maturation (EM1 and EM2) were studied. All gums presented good oil in water emulsifying capacities. However, after 20–60 high-pressure homogenization passes, matured gums formed more homogenous emulsions with smaller mean oil droplets (0.4 μm) than the control gum (0.65 μm). Modification of pH from 4.5 to 7.0 did not affect sample characteristics. The film-forming capability of all samples at air–water interface was studied using adsorbed and spread techniques. The greater the amount and molecular mass of the arabinogalactan protein (AGP) component in the gum, the better the interfacial properties (tension drop kinetic and interfacial tension final values). Good dilatational elasticity was found for all three gums samples, corresponding to highly elastic interfacial films. The spread films of matured gum EM2 rearranged during compression, passing through liquid expanded, liquid condensed into solid states. Conversely, control and EM1 gums only formed liquid expanded films and smaller surface coverage than EM2. Analytical interfacial results confirm the improved emulsifying properties of matured gums. The properties of the AGP molecules in the gums could be responsible for these differences.     

Protein extraction from lupin seeds: a mathematical model

The effect of particle size and microstructural modification on protein extraction from defatted lupin was studied. Particles of different sizes (128–1425 μm) from untreated (control), flaked and exploded samples were extracted at pH 8.0–8.5 and different temperatures. A three-parameter kinetic model as well as a diffusional model were fitted to data. The yield of protein from the surface of particles, and the total extracted protein yield increased as particle size decreased, while the first order rate constant increased slightly or remained constant. Diffusion coefficients varied between 0.5 and 4.5x10⁻¹² m² s⁻¹ and were higher in exploded and flaked material than in the control. The energy of activation for diffusion was 43 kJ mol⁻¹. Differences in microstructure were studied by scanning electron microscopy.     

A model food system for mass transfer in the acidification of cut root vegetables

The main objective of this work was to assess the adequacy of a 5% agarose gel to simulate the acetic acid acidification process in cut raw root vegetables. The process was well described by a Fickian model, and temperature dependence of diffusivity followed Arrhenius behaviour from 20 to 70°C with an activation energy of 16.8 kJ mol⁻¹. Equilibrium conditions were described with a constant partition coefficient of 0.94. External resistance to mass transfer was measurable under stagnant conditions and the mass transfer coefficients also changed with temperature as in an Arrhenius type equation with activation energy of 17.8 kJ mol⁻¹. Raw turnips and potatoes were acidified for comparison and the acid uptake followed a similar behaviour, although some differences in the parameters were observed. In general terms it was concluded that the 5% agarose gel is a suitable model food for studying acetic acid processing of raw root vegetables with exposed cut surfaces.     

Heat of sorption of water in dried fruits

The heats of moisture adsorption and desorption in four dried fruits (sultana raisins, figs, prunes and apricots) were estimated from equilibrium sorption data, using the Clausius-Clapeyron equation in the temperature range 15–60°C. The net isosteric heat of sorption ( q st) decreased sharply from about 20 kJ mol⁻¹ water to near zero when the moisture content was increased from 0.05 to 0.50kg water kg⁻¹ dry matter. An exponential function was fitted to the experimental q st values at various moisture contents (X) , yielding two characteristic constants ( q 0 and X 0) for each fruit. Mean and total heats of sorption were calculated from the proposed empirical equation, which are useful for enthalpy prediction in food dehydration. The heats of desorption were higher than the heats of adsorption, indicating significant hysteresis in the sorption of water, especially in dried apricots.     

Partial characterization of the in situ activity of pectinesterase in Bramley apple

The characteristics of pectinesterase (PE) have been examined in waste material (peel, cores and offcuts) obtained from Bramley seedling apples barn stored for 2, 4 and 12 weeks. A crude enzyme extract was prepared by suspending the dried and milled apple waste in 0.1 m NaCl at pH 8.5. The activity of PE under standard assay conditions of 0.5% apple pectin, 0.1 m NaCl, pH 8.5 and 30°C was low, between 4 and 8 units g⁻¹ dry matter, but activities up to 60 units g⁻¹ dry matter were obtained at higher temperatures. The optimum temperature was 60°C with the enzyme stable up to 40°C with 5 min heating. The mean activation energy for PE in the three samples was calculated at 39.2 kJ mol⁻¹ K⁻¹. The optimum pH was high at 10.0 probably due to the PE assay measuring the extraction/solubilization and stability of the enzyme in addition to its activity. Optimum activity was obtained in 0.15 m NaCl with optimum stability at 0.5 m.     

Characterization of Gum Ghatti (Anogeissus latifolia): A Structural and Rheological Approach

ABSTRACT:  Gatifolia, a commercial gum ghatti ( Anogeissus latifolia ) product was studied for its structural, thermal, and rheological characteristics. This study may prove helpful for the use of gum ghatti in a diverse range of food applications. The molecular weight ( M _W) and  R_g  (radius of gyration) for gum ghatti were calculated to be approximately 8.94 × 10⁷ g/mol and 140 nm, respectively, using high-performance size exclusion chromatography (HPSEC) system combined with multi-angle laser light scattering (MALLS). Gum ghatti solutions exhibited pseudoplastic behavior (as determined by flow experiments), which became more prevalent with increasing concentrations. Gum ghatti also displayed time-dependent shear-thickening behavior and showed negative hysteresis during up–down flow measurements. Under the measurement conditions at the range of frequencies and temperatures studied, the gum did not behave as a typical viscoelastic gel.     

Extraction methods and some physical properties of mesquite (Prosopis chilensis (Mol) Stuntz) seed gum

To evaluate the potential use of mesquite (Prosopis chilensis (Mol) Stuntz) seed gum, the behaviour of the gum was studied using two extraction methods (alkaline and acid), different pH values, two concentrations (0.2 and 0.4% w/v) and different temperatures. The capacity of the gum to stabilise food foams was also evaluated. The alkaline extraction yield (24.9%) was higher than the acid extraction yield (17.7%). Owing molecular to hydrolysis caused by the acid, acid extraction resulted in a lower protein content. Gum from acid extraction had a higher viscosity than that from alkaline extraction at all temperatures investigated (10, 20, 30, 40, 50 and 60 °C). There were no significant differences between the viscosities of mucilage dispersions at the different values of pH studied (3.0, 4.0 and 5.0). The addition of extracted mesquite gum (obtained by either method and at either concentration studied) to egg white foam provided a higher stability and decreased the liquid drainage and collapse of the foam. Copyright © 2004 Society of Chemical Industry     

Digestible energy value of gums in the rat--data on gum arabic

Male Wistar rats were fed a defined formula diet free from non-starch polysaccharides and either containing no additive or supplemented with gum arabic or cellulose or starch. Food and faeces were analysed by bomb calorimetry both to assess the effect of these substances on the apparent digestibility of dietary gross energy and to ascribe digestible energy values to the supplements. The former was not affected by starch and was decreased more by cellulose than by gum arabic. The energy values obtained were 17.4 +/- 0.4 kJ/g starch, 1.7 +/- 0.6 kJ/g cellulose and 14.7 +/- 0.5 kJ/g gum arabic. The latter is consistent with the high apparent digestibility of gum arabic in vivo and casts doubt on the validity of growth assay procedures that suggest a near-zero energy value for gum arabic.     

Comparison of Gum Arabic, Modified Starch, and Whey Protein Isolate as Emulsifiers: Influence of pH, CaCl2 and Temperature

ABSTRACT: The particle size and zeta potential of model beverage emulsions (0.01 wt% soybean oil-in-water emulsions, d ≅ 1 mm) stabilized by gum arabic, modified starch, or whey protein isolate (WPI) were studied with varying pH (3 to 9), CaCl₂ concentration (0 to 25 mM), and temperature (30 °C to 90 °C). Temperature, pH, CaCl₂ strongly influenced emulsions stabilized by WPI because its stabilizing mechanism was mainly electrostatic repulsion, but not those stabilized by gum arabic or modified starch because their stabilizing modes of action were mainly steric repulsion. This study may have important implications for the application of WPI as an emulsifier in beverage emulsions.     

Rheological characterization of dispersions and emulsions used in the preparation of microcapsules obtained by interfacial polymerization containing <Emphasis Type="Italic">Lactobacillus</Emphasis> sp.

The main objectives of this work were the rheological characterization of dispersions and emulsions used in the microcapsules preparation and the microcapsules obtain from gum arabic (A), gellan gum (G) and mesquite seed gum (M) to keep lactic bacteria (Lactobacillus sp.) viable using the interfacial polymerization technique (IP). Dispersions of A, G and M were prepared to obtain microcapsules, as well as binary mixtures of gum arabic and gellan gum (AG), gum arabic and mesquite seed gum (AM) and gellan gum and mesquite seed gum (GM); these dispersions exhibited a shear thinning non-Newtonian behavior. The emulsions were prepared using sunflower oil as the oily phase in a 1:1, 1:3 and 1:5 ratio with the disperse phase; the oily phase was added with Span 85 (surfactant) at 1, 2 and 3% concentrations; the emulsions A (1:5 and 3% Span 85) and GM (1:5 and 2% Span 85) showed higher viscosity and stability. Microcapsules were obtained using 0.05 mol L⁻¹ glutaraldehyde (crosslinking agent) with a reaction time of 3 min. The mean diameter of the microcapsules obtained was 30.17, 16.86 and 10.34 μm according to the AG, AM and GM mixtures, respectively. In the AG and AM dispersions, the microcapsules diameters became larger as the viscosity increased. The microorganism microencapsulates using gum arabic, gellan gum, and mesquite seed gum, was possible. The highest viability (46.7%) of Lactobacillus sp. was obtained with the GM mixture.     

Effect of the presence of gum arabic on the thermostability of thaumatin

Summary The objective of this research was to evaluate the effect of gum arabic on thermostability of thaumatin. Thermodegradation of solutions of thaumatin with gum arabic at various temperatures (50, 70 and 90 °C) was studied. This degradation appeared to follow first‐order kinetics at whatever temperature was used for thermodegradation. The experiments revealed an activation energy (E_a) of 41.4 kJ mol^?1 and a t_90% (time necessary to obtain a decrease of 10% of the initial concentration) of about 24 days for thaumatin with gum arabic, at 20 °C, at pH 4.90.     

Mathematical modelling of moisture sorption isotherms and determination of isosteric heat of blueberry variety O'Neil

The sorption isotherms of blueberry variety O'Neil were determined at 20, 40 and 60 °C, for a range of water activity of 0.10–0.95. The isotherms showed that the equilibrium moisture content increased when temperature decreased at constant water activity. The BET, GAB, Halsey, Henderson, Caurie, Smith, Oswin and Iglesias-Chirife equations were tested for modelling the sorption isotherms. The results showed that GAB, BET and Halsey models gave the best fit quality for the experimental desorption data, and BET, Oswin and Henderson for adsorption data as suggested by the statistical tests employed. The net sorption heat was calculated using the Clausius–Clapeyron equation giving 38.62 kJ mol⁻¹ (desorption) and 30.88 kJ mol⁻¹ (adsorption) at a moisture content of 0.01 g water (g d.m.⁻¹). Tsami equation was applied to estimate the net isosteric heat of sorption as function of equilibrium moisture content with satisfactory results.