E.J. Vernon-Carter

Estimation of the activation energy of carbohydrate polymers blends as selection criteria for their use as wall material for spray-dried microcapsules

A quantitative method for selecting the most suitable biopolymers blends for lipid materials microencapsulation is proposed. Aqueous solutions of carbohydrate polymers blends (gum arabic (GA), mesquite gum (MG) and maltodextrin DE 10 (MD)) were prepared in accordance to a Simplex Centroid experimental design, and a drop of each blend was dried isothermally at 50, 60 and 80 °C in a thermogravimetric analyzer. The effective diffusivity was dependent on moisture content, drop volume shrinkage, and temperature. Drop shrinkage was estimated from polynomial models reported for GA, MG and MD, assuming additive volumes of the blend constituents. Activation energies were calculated considering that the average effective diffusivity followed an Arrhenius-type relationship. The pure biopolymer exhibiting the highest activation energy was MD, followed by MG and GA, respectively. Blends containing 66%GA-17%MG-17%MD and 17%GA-66%MG-17%MD showed higher activation energies than MD, MG and GA suggesting that they better suited for protecting microencapsulated lipids against oxidation.

Mesquite gum: fractionation and characterization of the gum exuded from Prosopis laevigata obtained from plant tissue culture and from wild trees

Abstract The effect of abiotic and biotic stresses in the in vitro gum production from Prosopis laevigata has been studied. The presence of autoclaved microbial biomass (MB) in combination with an incubation temperature of 35 °C induced the greatest gum production. In vitro and in situ gum samples from mesquite were fractionated by hydrophobic affinity chromatography. The results indicated that both gums consist of five principal fractions. The protein content of the fractions varied greatly (0.04–50.05%). For both gums, the protein content in the fractions (F) increased in the following order F2a

Using biopolymer blends for shrimp feedstuff microencapsulation - I. Microcapsule particle size, morphology and microstructure

A shrimp feedstuff was microencapsulated through spray drying using different biopolymer treatments as wall materials after a three component Simplex Centroid experimental design, employing wall material to feedstuff ratios of 2:1 and 3:1, and pH values of 4 and 8. The response surface methodology indicated that the three above mentioned variables affected the microcapsule particle size and microstructure, as evidenced by scanning electron microscopy. Predictive equations show that the factor that affected significantly the microcapsule particle size was the binary interactions among the biopolymers. The higher the wall material-feedstuff ratio the larger the microcapsule particle size. As pH varied from 4 to 8, the biopolymer adsorbed layers around the core material were more extended. All the resulting microcapsules were of the matrix type, in which the feedstuff microparticles were distributed within the solid wall material matrix.

Prosopis laevigata a potential chromium (VI) and cadmium (II) hyperaccumulator desert plant.

The bioaccumulation of Cr(VI) and Cd(II) in Prosopis laevigata and the effect of these heavy metals on plant growth were assessed. P. laevigata seeds were cultured during 50 days on modified Murashige-Skoog medium supplemented with four different concentrations of Cr(VI) (0-3.4mM) and Cd(II) (0-2.2mM), respectively. Heavy metals did not stop germination, but smaller plants with fewer leaves and secondary roots were produced. Seedlings showed an accumulation of 8176 and 21,437 mg Cd kg(-1) and of 5461 and 8090 mg Cr kg(-1) dry weight, in shoot and root, when cultured with 0.65 mM Cd(II) and 3.4mM Cr(VI), respectively. These results indicated that significant translocation from the roots unto aerial parts took place. A bioaccumulation factor greater than 100 for Cd and 24 for Cr was exhibited by the seedlings. P. laevigata can be considered as a potential hyperaccumulator of Cd(II) and Cr(VI) species and considered as a promising candidate for phytoremediation purposes.

Moisture barrier properties and morphology of mesquite gum–candelilla wax based edible emulsion coatings

Abstract Composite edible coatings were formulated with candelilla wax alone, and candelilla wax blended with beeswax, white mineral oil and oleic acid (2:1 ratios) as the lipid phase, and mesquite gum as the structural material and their corrected water vapor permeability (WVPc) were determined. The coatings were applied to Persian limes and their effect upon physiological weight loss, color and chemical composition changes were evaluated. Addition of the blend of candelilla wax–mineral oil improved the WVPc ( P

Mesquite gum (Prosopis gum)

Publisher Summary Mesquite gum, or Prosopis gum, was widely used by the Indian cultures of central northwestern Mexico (Seri and Yaqui) and the southwestern United States (Papago, Pima) since pre-Columbian times, mainly as a sweet, an ingredient in human and animal feedstuffs, and as a medicinal aid for sore eyes, sore throat, stomach ache, diarrhea, for preventing infections, and for the treatments of open wounds. Mesquite gum has been extensively used in Mexico and the southwestern United States in small processing industries, mainly dealing with foodstuffs and confectionery goods. It was listed in the Mexican Pharmacopoeia from 1874 until 1974, after which it disappeared from the lists because of the almost inexistent supply of the gum caused by the terrible plight of the mesquite trees in Mexico. This was because of the extension of grazing lands for cattle and the increasing demand for mesquite coal and wood for barbecues. As a consequence, a terrible desertification of Mexico has occurred, as the root of the mesquite tree penetrates deep into the soil retaining it. This fact plus cyclical shortages in the supply of gum Arabic and its increasing price have led to a drive to reforest the Mexican arid and semi-arid lands with the mesquite tree and to substitute the use of gum Arabic with mesquite gum.

Acid hydrolysis of native corn starch: Morphology, crystallinity, rheological and thermal properties

The acid hydrolysis of native corn starch at 35 °C was monitored during 15 days. After this time, the residual solids were about 37.0 ± 3.0%. First-order kinetics described the hydrolysis data, giving a constant rate of kH = 0.18 ± 0.012 days(-1). Amylose content presented a sharp decrement of about 85% and X-ray diffraction results indicated a gradual increase in crystallinity during the first 3 days. SEM micrographs showed that hydrolysis disrupted granule morphology from an initial regular shape to increasingly irregular shapes. Fractal analysis of SEM images revealed an increase in surface roughness. Fast changes in the thermal effects were caused by molecular rearrangements after fast hydrolysis of amylose in the amorphous regions in the first day. Steady shear rate and oscillatory tests showed a sharp decrease of the apparent viscosity and an increase of the damping factor (tan(δ)) caused by amylose degradation.

Utilization of mesquite (Prosopis juliflora) gum as emulsion stabilizing agent for spray-dried encapsulated orange peel oil

Abstract Orange peel oil was microencapsulated. Mesquite gum and its performance for producing spray-dried powders was compared to emulsions prepared with gum arabic. Average oil droplet size of mesquite gum capsules was smaller than that of gum arabic. Emulsions made with mesquite gum showed better stability than those made with gum arabic. Encapsulation capacity of mesquite gum was found to be 80.5 % of the starting oil whereas gum arabic was able to encapsulate 93.5 %. Sensory evaluation showed that there was not significant difference (α<0.05) in flavor intensity between orange peel oil encapsulated with the two emulsifiers.

In vitro digestibility, physicochemical, thermal and rheological properties of banana starches.

Banana starches (BS) were isolated from Enano, Morado, Valery and Macho cultivars. The BS possessed B-type crystallinity and an amylose content varying from 19.32 to 26.35%. Granules had an oval morphology with different major-to-minor axis ratios, exhibiting both mono- and bi-modal distributions and mean particle sizes varying from 32.5 to 45 μm. BS displayed zeta-potential values ranging between -32.25 and -17.32 mV, and formed gels of incipient to moderate stability. The enthalpy of gelatinization of BS affected the crystalline order stability within the granules. In-vitro digestibility tests showed fractions as high as 68% of resistant starch. Rheological oscillatory tests at 1 Hz showed that BS dispersions (7.0%, w/w) exhibited Type III behaviour, attributed to the formation of a continuous phase complex three-dimensional amylose gel reinforced by swollen starch granules acting as fillers. Amylose content and granules morphology were the main factors influencing the BS properties.

Effect of foaming agents on the stability, rheological properties, drying kinetics and flavour retention of tamarind foam-mats

Abstract Tamarind foam-mats were prepared using as foaming agents ovalbumin, mesquite gum and a low molecular weight surface active blend, by themselves or in combination, in accordance to a 2 3 factorial experimental design. The stability, rheological properties (flow and viscoelasticity) and drying kinetics of the different foam treatments were evaluated. Sensory evaluation of the dried powders was performed. Response surface analysis yielded polynomial models that explain the influence of the foaming agents treatments on the selected foams response variables: drainage mean time, yield stress, apparent plastic viscosity, critical drying time, instantaneous elastic modulus, and mean retardation time. In general terms, the use of binary combinations of the foaming agents at their high usage level yielded foams that exhibited longer drainage mean times; higher yield stress, apparent plastic viscosity, instantaneous elastic modulus and mean retardation times; and a shorter onset of the critical drying time, that yielded dried tamarind powders with better sensory flavour perception. A close interrelationship existed between the drainage mean time and the apparent plastic viscosity, and between the critical drying time and the mean retardation time of the foams.