Zeta potential and drop growth of oil in water emulsions stabilized with mesquite gum

Fabrication of Pickering emulsions stabilized by citrus pectin modified with β-cyclodextrin and its application in 3D printing

Pickering emulsions stabilized by polysaccharide particles have received increasing attention because of their potential applications in three-dimensional (3D) printing. In this study, the citrus pectins (citrus tachibana, shaddock, lemon, orange) modified with β-cyclodextrin (β-CD) were used to stabilize Pickering emulsions reaching the requirements of 3D printing. In terms of pectin chemical structure, the steric hindrance provided by the RG I regions was more conducive to the stability of the complex particles. The modification of pectin by β-CD provided the complexes a better double wettability (91.14 ± 0.14°-109.43 ± 0.22°) and a more negative ζ-potential, which was more beneficial for complexes to anchor at oil-water interface. In addition, the rheological properties, texture properties and stability of the emulsions were more responsive to the ratios of pectin/β-CD (R_β/C). The results showed that the emulsions stabilized at a φ = 65 % and a R_β/C = 2:2 achieved the requirements (shear thinning behavior, self-supporting ability, and stability) of 3D printing. Furthermore, the application in 3D printing demonstrated that the emulsions under the optimal condition (φ = 65 % and R_β/C = 2:2) displayed excellent printing appearance, especially for the emulsions stabilized by β-CD/LP particles. This study provides a basis for the selection of polysaccharide-based particles to prepare 3D printing inks which may be utilized in food manufacturing.

Probing the Mechanism of Targeted Delivery of Molecular Surfactants Loaded into Nanoparticles after Their Assembly at Oil-Water Interfaces

A targeted and controlled delivery of molecular surfactants at oil-water interfaces using the directed assembly of nanoparticles, NPs, is reported. The mechanism of NP assembly at the interface and the release of molecular surfactants is followed by laser scanning confocal microscopy and surface force spectroscopy. The assembly of positively charged polystyrene NPs at the oil-water interface was facilitated by the introduction of carboxylic acid groups in the oil phase (e.g., by adding 1 wt % stearic acid to hexadecane to produce a model oil). The presence of positively charged NPs consistently lowers the stiffness of the water-oil interface. The effect is lessened, when the NPs are present in a solution of NaCl or deionized water at pH 2, consistent with a less dense monolayer of NPs at the interface in the last two systems. In addition, the NPs reduce the interfacial adhesion (i.e., the "stickiness" of the interface or, put differently, the pull-off force experienced by the atomic force microscopy (AFM) tip during retraction). After the assembly, the NPs can release a previously loaded cargo of surfactant molecules, which then facilitate the formation of a much finer oil-water emulsion. As a proof of concept, we demonstrate the release of octadecyl amine, ODA, that has been incorporated into the NPs prior to the assembly. The release of ODA causes the NPs to detach from the interface altering the interfacial properties and leads to finer oil droplets. This approach can be exploited in applications in several fields ranging from pharmaceutical and cosmetics to hydrocarbon recovery and oil-spill remediation, where a targeted and controlled release of surfactants is wanted.

Essential Oils and Hydrolates: Potential Tools for Defense against Bacterial Plant Pathogens

The essential oils (EOs) of Origanum compactum and Satureja montana chemotyped (CT) at carvacrol, two Thymus vulgaris CT at thujanol and thymol, and Hydrolates (Hys) of S. montana and Citrus aurantium var. amara were chosen for studying their bactericidal efficacy against few phytobacterial pathogens. The Minimal Inhibitory Concentration (MIC) and Bactericidal Concentration (MBC) were found by microdilution assay. The essential oils of O. compactum (MBC 0.06% v/v), T. vulgaris CT thymol (MBC 0.06% v/v), and Hy of C. aurantium (MBC 6.25% v/v) resulted in being the most effective against Erwinia amylovora; thus, they were used as starting concentrations for ex vivo assays. Despite the great in vitro effectiveness, the disease incidence and the population dynamic ex vivo assays showed no significant results. On the other hand, EO of O. compactum and Hy of C. aurantium (at 0.03% and 4.5% v/v, respectively) showed resistance induction in tomato plants against Xanthomonas vesicatoria infections; both treatments resulted in approximately 50% protection. In conclusion, EOs and Hys could be promising tools for agricultural defense, but further studies will be necessary to stabilize the EOs emulsions, while Hys application could be an effective method to prevent bacterial diseases when used as resistance inducer by pre-transplantation treatment at roots.

Current Insights into Phytochemistry, Nutritional, and Pharmacological Properties of Prosopis Plants

Prosopis is a regional cash crop that is widely grown in arid, semiarid, tropical, and subtropical areas. Compared with other legume plants, Prosopis is underutilized and has great potentialities. Prosopis not only is a good source of timber, construction, fencing material, and gum, but also can be applied for food, beverage, feed, and medicine. Prosopis contains numerous phytochemical constituents, including carbohydrates, proteins, fatty acids, minerals, and vitamins, while varieties of phenolic compounds have also been identified from different parts of Prosopis. Flavonoids (especially C-glycosyl flavonoids), tannins, catechin, 4′-O-methyl-gallocatechin, mesquitol, and quercetin O-glycosides are significant phenolic contents in Prosopis. Various extracts of Prosopis displayed a wide range of biological properties, such as antioxidant, antihyperglycemic, antibacterial, anthelmintic, antitumor, and anticancer. Additionally, Prosopis has the potential to be an ideal diet that contains abundant dietary fiber, minerals, galactomannans, and low-fat content. However, the bioactivity and pharmacological properties associated with Prosopis were influenced by the bioavailability of phytochemicals, various antinutritional compounds, and the interactions of protein and phenolic compounds. The bioavailability of Prosopis is mainly affected by phenolic contents, especially catechin. The antinutritional compounds negatively affect the nutritional qualities of Prosopis, which can be prevented by heating. The protein-phenolic compound interactions can help the human body to absorb quercetin from Prosopis. This literature review aimed to provide systematic information on the physical, biochemical, pharmacological, and nutritional properties and potential applications of Prosopis.

Physicochemical, Rheological, Structural, Antioxidant, and Antimicrobial Properties of Polysaccharides Extracted from Tamarind Seeds

In this study, the polysaccharides were firstly extracted from the tamarind seeds in which the crude polysaccharides have been extracted once by hot water extraction. The structure was characterized by FTIR, SEM, and X-ray diffraction after removing protein and small molecule impurities. Furthermore, the rheological and bioactivity of tamarind seed polysaccharides (TSP) were also investigated. The results indicated that the yield of the obtained polysaccharide was 3.42%. TSP was mainly composed of glucose (45.09%), galactose (22.80%), and xylose (28.89%), while it contained characteristic structure of polysaccharides, such as –OH, pyranose, and uronic acid at 3,418, 1,150, and 1,040 cm−1 respectively, which demonstrated that it was a uronic acid heteropolysaccharide. Moreover, the XRD pattern revealed the amorphous behavior of TSP, and it was found to consist of films or “sheets” reflected by SEM. The flow behavior testing confirmed its pseudoplastic character, and the flow behavior index (n) was between 0.4539 and 0.9201. The DPPH radical scavenging activity of TSP was 40.34% at 10 mg/mL. Furthermore, TSP displayed moderate hydroxyl radical scavenging and anti-bacterial activities, owing to its special structure and composition. Overall, our results suggested that TSP could be used as a food ingredient with anti-oxidative and antibacterial activities, which provides useful information on the potential utilization of TSP in the food industry.

Functionalization of silica-coated magnetic nanoparticles as powerful demulsifier to recover oil from oil-in-water emulsion

This study presents an innovative approach for the preparation of Fe₃O₄ nanoparticles covered with SiO₂ shell (denoted as Fe-Si-MNP), which were used to recover oil recovery from oil-in-water emulsion (O/W-emul). The Fe-Si-MNP were prepared with differing silica layer thicknesses (5 nm [Fe-Si-1], 8 nm [Fe-Si-2], 10 nm [Fe-Si-3], and 15 nm [Fe-Si-4]) and tested for the percentage of oil separation (%S_oil) under different dosages (D_MNP), oil concentration (D_oil), surfactant dosages (D_sur), and pH. The Fe-Si-MNP exhibited excellent %S_oil, reliable stability, and high magnetization values ranging between 46.1 and 80.2 emu/g. adding a 5 nm silica layer on the surface of the Fe-Si-MNP (i.e., Fe-Si-1) protected them from oxidation conditions, extended their service life, and achieved a %S_oil of ∼96.3%. The %S_oil slightly decreased to ∼92% with an alkaline pH or when the thickness of the silica layer increased to ≥10 nm. The %S_oil was 90.5%, 89.5%, and 87.5% for Fe-Si-2, Fe-Si-3, and Fe-Si-4, respectively. Increasing the water salinity from 0.1 to 0.5 M slightly improved the %S_oil for the tests carried out with a D_oil of 100 mg/L to 93.3%, 90.3%, and 86.3% for Fe-Si-2, Fe-Si-3, and FeSi-4, respectively. The highest %S_oil achieved with Fe- Si-1 Fe-Si-2 and Fe-Si-3 was >95%, 95% and 92%, respectively. The Fe-Si-MNP exhibited a high recyclability for 9 cycles with the lowest %S_oil ∼80%. The results suggest that the structure and properties of the Fe-Si-MNP can be manipulated to achieve a high oil recovery, easy separation, and extended service life.

Electrosteric stabilization of oil/water emulsions by adsorption of chitosan oligosaccharides-An electrokinetic study

The present study was focused on investigation of electrokinetic behaviour of lecithin-stabilized oil/water emulsions in the presence of chitosan oligosaccharides (COS). The oligosaccharides give unique opportunity for precisely characterization of the properties of chitosan as a function of the degree of acetylation (DA) and degree of polymerization (DP) of the polymer. For the study were chosen well characterized ultra pure COS molecules with completely acetylated monomers and mixture of COS molecules with acetylated and deacetylated monomers. The obtained results confirmed experimentally for the first time, the suggestion for the predominant contribution of hydrophobic (at high DA) and electrostatic (at low DA) interactions between chitosan monomers and the lecithin-covered droplet surface.

Investigation of hot air and foam-mat dried cress seed gum by FT-IR, zeta potential, steady shear viscosity, dynamic oscillatory behavior, and other physical properties

The effects of different drying methods (hot air drying at 40, 60, and 80°C, and foam-mat drying) on the characteristics (FT-IR, zeta potential, conductivity, color, rheology, texture, and emulsifying) of extracted cress seed gum (CSG) have been investigated. The models described the rheological behavior of CSG with high R 2, but in general Herschel-Bulkley's model has higher values of R 2 and lower values of RMSE compared to the fitted models. The HD 80 has high amount of viscosity. This means that as the temperature rises, the gel network is getting stronger, and gums from the internal CSG sections have a stronger gel network. Results of strain sweep test demonstrated that storage ( G LVE ' ) and loss modulus ( G LVE ″ ) for all solutions except foam-mat drying in the linear area showed solid-like behavior. The parameters of strain sweep (Gf, τf, τy, G LVE ″ , G LVE ' , YLVE) increased with increasing temperatures. Frequency sweep test showed that storage ( G LVE ' ) was greater than loss modulus ( G LVE ″ ) and samples have a solid behavior but foam-mat drying exhibited liquid behavior. Increasing temperature has a direct impact on texture, so hardness and adhesion are increased consequently. Generally, CSG has good emulsifying and foaming characteristics, but no significant difference was observed.

Cross-Linking Chitosan into Hydroxypropylmethylcellulose for the Preparation of Neem Oil Coating for Postharvest Storage of Pitaya (Stenocereus pruinosus)

The market trend for pitaya is increasing, although the preservation of the quality of this fruit after the harvest is challenging due to microbial decay, dehydration, and oxidation. In this work, the application of antimicrobial chitosan-based coatings achieved successful postharvest preservation of pitaya (Stenocereus pruinosus) during storage at 10 ± 2 °C with a relative humidity of 80 ± 5%. The solution of cross-linked chitosan with hydroxypropylmethylcellulose with entrapped Neem oil (16 g·L^-1) displayed the best postharvest fruit characteristics. The reduction of physiological weight loss and fungal contamination, with an increased redness index and release of azadirachtin from the microencapsulated oil, resulted in up to a 15 day shelf life for this fruit. This postharvest procedure has the potential to increase commercial exploitation of fresh pitaya, owing to its good taste and high content of antioxidants.

Exploring the Potential of Mesquite Gum-Nopal Mucilage Mixtures: Physicochemical and Functional Properties

In this work the physicochemical and functional properties of mesquite gum (MG) and nopal mucilage (NM) mixtures (75-25, 50-50, 25-75) were evaluated and compared with those of the individual biopolymers. MG-NM mixtures exhibited more negative zeta potential (ZP) values than those displayed by MG and NM, with 75-25 MG-NM showing the most negative value (-14.92 mV at pH = 7.0), indicative that this biopolymer mixture had the highest electrostatic stability in aqueous dispersions. Viscosity curves and strain amplitude sweep of aqueous dispersions (30% w/w) of the individual gums and their mixtures revealed that all exhibited shear thinning behavior, with NM having higher viscosity than MG, and all displaying fluid-like viscoelastic behavior where the loss modulus predominated over the storage modulus (G″>G'). Differential Scanning Calorimetry revealed that MG, NM, and MG-NM mixtures were thermally stable with decomposition peaks in a range from 303.1 to 319.6 °C. From the functional properties viewpoint, MG (98.4 ± 0.7%) had better emulsifying capacity than NM (51.9 ± 2.0%), while NM (43.0 ± 1.4%) had better foaming capacity than MG. MG-NM mixtures acquired additional functional properties (emulsifying and foaming) regarding the individual biopolymers. Therefore, MG-NM mixtures represent interesting alternatives for their application as emulsifying and foaming agents in food formulations.

PRACTICAL APPLICATION

Mesquite gum (MG) and nopal mucilage (NM) are promising raw materials with excellent functional properties whose use has been largely neglected by the food industry. This work demonstrates MG-NM mixtures acquired additional functional properties regarding the individual biopolymers, making these mixtures multifunctional ingredients for the food industry.

Curcumin-loaded sterically stabilized nanodispersion based on non-ionic colloidal system induced by ultrasound and solvent diffusion-evaporation

Curcumin has been found to possess significant pharmaceutical activities. However, owing to its low bioavailability, there is a limitation of employing it towards clinical application. In an attempt to surmount this implication, often the choice is designing novel drug delivery systems. Herein, sterically stabilized nanoscale dispersion loaded with curcumin (nanodispersion) based on non-ionic colloidal system has been proposed. In this study, the process conditions were effectively optimized using response surface methodology (RSM) with Box–Behnken design (BBD). The suggested optimum formulation proved to be an excellent fit to the actual experimental output. STEM images illustrate that the optimal curcumin-loaded nanodispersion has spherical morphology with narrow particle size distribution. Particle size distribution study confirms that the solution pH does not affect the nanodispersion, and physical stability study shows that the colloidal system is stable over 90 days of storage at ambient conditions. More importantly, controlled release profile was achieved over 72 h and the in vitro drug release data fit well to Higuchi model (R2=0.9654).

Evaluation of the stability of concentrated emulsions for lemon beverages using sequential experimental designs

The study of the stability of concentrated oil-in-water emulsions is imperative to provide a scientific approach for an important problem in the beverage industry, contributing to abolish the empiricism still present nowadays. The use of these emulsions would directly imply a reduction of transportation costs between production and the sales points, where dilution takes place. The goal of this research was to evaluate the influence of the main components of a lemon emulsion on its stability, aiming to maximize the concentration of oil in the beverage and to correlate its physicochemical characteristics to product stability, allowing an increase of shelf life of the final product. For this purpose, analyses of surface and interface tension, electrokinetic potential, particle size and rheological properties of the emulsions were conducted. A 2^4-1 fractional factorial design was performed with the following variables: lemon oil/water ratio (30% to 50%), starch and Arabic gum concentrations (0% to 30%) and dioctyl sodium sulfosuccinate (0 mg/L to 100 mg/L), including an evaluation of the responses at the central conditions of each variable. Sequentially, a full design was prepared to evaluate the two most influential variables obtained in the first plan, in which concentration of starch and gum ranged from 0% to 20%, while concentration of lemon oil/water ratio was fixed at 50%, without dioctyl sodium sulfosuccinate. Concentrated emulsions with stability superior to 15 days were obtained with either starch or Arabic gum and 50% lemon oil. The most stable formulations presented viscosity over 100 cP and ratio between the surface tension of the emulsion and the mucilage of over 1. These two answers were selected, since they better represent the behavior of emulsions in terms of stability and could be used as tools for an initial selection of the most promising formulations.