Physical and chemical stability of gum arabic-stabilized conjugated linoleic acid oil-in-water emulsions

Comparative neuroprotective effects of royal jelly and its unique compound 10-hydroxy-2-decenoic acid on ischemia-induced inflammatory, apoptotic, epigenetic and genotoxic changes in a rat model of ischemic stroke

OBJECTIVES

This study aimed to compare the efficacy of royal jelly (RJ) and its major fatty acid 10-hydroxy-2-decenoic acid (10-HDA) on ischemic stroke-related pathologies using histological and molecular approaches.

METHODS

Male rats were subjected to middle cerebral artery occlusion (MCAo) to induce ischemic stroke and were supplemented daily with either vehicle (control group), RJ or 10-HDA for 7 days starting on the day of surgery. On the eighth day, rats were sacrificed and brain tissue and blood samples were obtained to analyze brain infarct volume, DNA damage as well as apoptotic, inflammatory and epigenetic parameters.

RESULTS

Both RJ and 10-HDA supplementation significantly reduced brain infarction and decreased weight loss when compared to control animals. These effects were associated with reduced levels of active caspase-3 and PARP-1 and increased levels of acetyl-histone H3 and H4. Although both RJ and 10-HDA treatments significantly increased acetyl-histone H3 levels, the effect of RJ was more potent than that of 10-HDA. RJ and 10-HDA supplementation also alleviated DNA damage by significantly reducing tail length, tail intensity and tail moment in brain tissue and peripheral lymphocytes, except for the RJ treatment which tended to reduce tail moment in lymphocytes without statistical significance.

CONCLUSIONS

Our findings suggest that neuroprotective effects of RJ in experimental stroke can mostly be attributed to 10-HDA.

Preparation and characterization of sodium caseinate-apricot tree gum/gum Arabic nanocomplex for encapsulation of conjugated linoleic acid (CLA)

Nanocomplexes (NCs) were formed through electrostatic complexation theory using Na-caseinate (NaCa), gum Arabic (GA), and Prunus armeniaca L. gum exudates (PAGE), aimed to encapsulate Conjugated linoleic acid (CLA). Encapsulation was optimized using NaCa (0.1 %-0.5 %), GA/PAGE (0.1 %-0.9 %) and CLA (1 %-5 %), and central composite design (CCD) was employed for numerical optimization. The optimum conditions for NC containing GA (NCGA) were 0.336 %, 0.437 %, and 3.10 % and for NC containing PAGE (NCPAGE) were 0.403 %, 0.730 %, and 4.177 %, of NaCa, GA/PAGE, and CLA, respectively. EE and particle size were 92.46 % and 52.89 nm for NCGA while 88.23 % and 54.76 nm for NCPAGE, respectively. Fourier transform infrared spectroscopy (FTIR) indicated that CLA was physically entrapped. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed the electrostatic complex formation. The elastic modulus was predominant for NCGA and NCPAGE dispersions while the complex viscosity of NCPAGE suspension was slightly higher than that of NCGA. The CLA in NCGA-CLA and NCPAGE-CLA exhibited higher oxidative stability than free CLA during 30 days of storage without a significant difference between the results of CLA oxidative stability tests obtained for NCs. Consequently, NCPAGE and NCGA could be applied for the entrapment and protection of nutraceuticals in the food industry.

Correlation between interfacial layer properties and physical stability of food emulsions: current trends, challenges, strategies, and further perspectives

Emulsions are thermodynamically unstable systems that tend to separate into two immiscible phases over time. The interfacial layer formed by the emulsifiers adsorbed at the oil-water interface plays an important role in the emulsion stability. The interfacial layer properties of emulsion droplets have been considered the cutting-in points that influence emulsion stability, a traditional motif of physical chemistry and colloid chemistry of particular significance in relation to the food science and technology sector. Although many attempts have shown that high interfacial viscoelasticity may contribute to long-term emulsion stability, a universal relationship for all cases between the interfacial layer features at the microscopic scale and the bulk physical stability of the emulsion at the macroscopic scale remains to be established. Not only that, but integrating the cognition from different scales of emulsions and establishing a unified single model to fill the gap in awareness between scales also remain challenging. In this review, we present a comprehensive overview of recent progress in the general science of emulsion stability with a peculiar focus on interfacial layer characteristics in relation to the formation and stabilization of food emulsions, where the natural origin and edible safety of emulsifiers and stabilizers are highly requested. This review begins with a general overview of the construction and destruction of interfacial layers in emulsions to highlight the most important physicochemical characteristics of interfacial layers (formation kinetics, surface load, interactions among adsorbed emulsifiers, thickness and structure, and shear and dilatational rheology), and their roles in controlling emulsion stability. Subsequently, the structural effects of a series of typically dietary emulsifiers (small-molecule surfactants,proteins, polysaccharides, protein-polysaccharide complexes, and particles) on oil-water interfaces in food emulsions are emphasized. Finally, the main protocols developed for modifying the structural characteristics of adsorbed emulsifiers at multiple scales and improving the stability of emulsions are highlighted. Overall, this paper aims to comprehensively study the literature findings in the past decade and find out the commonality of multi-scale structures of emulsifiers, so as to deeply understand the common characteristics and emulsification stability behaviour of adsorption emulsifiers with different interfacial layer structures. It is difficult to say that there has been significant progress in the underlying principles and technologies in the general science of emulsion stability over the last decade or two. However, the correlation between interfacial layer properties and physical stability of food emulsions promotes revealing the role of interfacial rheological properties in emulsion stability, providing guidance on controlling the bulk properties by tuning the interfacial layer functionality.

Emulsion Stabilization Strategies for Tailored Isocyanate Microcapsules

We report on the stabilization of an oil-in-water (O/W) emulsion to, combined with interfacial polymerization, produce core-shell polyurea microcapsules (MCs) containing isophorone diisocyanate (IPDI). These will act as crosslinkers for mono-component adhesives. The emulsion stabilization was evaluated using three types of stabilizers, a polysaccharide (gum arabic) emulsifier, a silicone surfactant (Dabco^®DC193), a rheology modifier (polyvinyl alcohol), and their combinations. Emulsion sedimentation studies, optical microscopy observation, and scanning electron microscopy enabled us to assess the emulsions stability and droplet size distribution and correlate them to the MCs morphology. Fourier transform infrared spectroscopy and thermogravimetric analysis revealed the MCs composition and enabled us to evaluate the encapsulation yield. All stabilizers, except DC193, led to spherical, loose, and core-shelled MCs. The rheology modifier, which increases the continuous phase viscosity, reduces the emulsion droplets sedimentation, keeping their size constant during the MCs' synthesis. This allowed us to obtain good quality MCs, with a smaller average diameter, of approximately 40.9 µm mode, a narrower size distribution and 46 wt% of encapsulated IPDI. We show the importance of the emulsion stability to tune the MCs morphology, size, and size distribution, which are critical for improved homogeneity and performance when used, e.g., in natural and synthetic adhesive formulations industry.

Enhancement of physicochemical and encapsulation stability of O1/W/O2 multiple nanoemulsions loaded with coenzyme Q10 or conjugated linoleic acid by incorporating polyphenolic extract

Multiple O1/W/O2 nanoemulsions and O1/W nanoemulsions fortified with CLA or CoQ10 were produced using extra virgin olive or olive pomace oil and were also incorporated with polyphenols extracted from olive kernel to enhance their kinetic and chemical stability. They were prepared using a high-speed ultrasonic homogenizer. Specifically, nanoemulsions with 6 wt% lipid phase and 6 wt% non-ionic emulsifier (Tween 40) were produced and they demonstrated a droplet diameter >200 nm and high encapsulation stability during 30 days of storage at 4 °C or 25 °C. The incorporation of CLA or CoQ10 and polyphenolic compounds facilitated the homogenization of emulsions, reducing the droplet size and enhancing their chemical stability, and their bioactive retention values were >79%. O1/W/O2 nanoemulsions were produced using a mixture of non-ionic emulsifiers (Span 20 and Tween 40) and the O1/W enriched nanoemulsion as the dispersed phase. All multiple emulsions showed a bimodal droplet size distribution and Newtonian behavior while polyphenols facilitated their homogenization. Both vegetable oils resulted in samples with high kinetic and chemical stability; the bioactive retention values were found to be >80% at the end of 30 days of storage at 4 °C or 25 °C. Extra virgin olive oil resulted in more stable nanoemulsions in regards to kinetic and chemical stability at 4 °C, showing limited creaming and sedimentation boundary. Multiple nanoemulsions with the lowest initial droplet size presented the lowest droplet diameter growth and phase separation and the highest retention values. By comparing O1/W nanoemulsions and O1/W/O2 nanoemulsions, we noted that the reduction in the total phenolic content and antioxidant activity during storage was higher in the O1/W type. However, both delivery systems protected CLA and CoQ10 presenting high retention during storage. FTIR spectra before and after ultrasonic homogenization indicated that the sonication process did not significantly affect the lipid phase of O1/W/O2 nanoemulsions.

Co-encapsulation of L-ascorbic acid and quercetin by gelatin/sodium carboxymethyl cellulose coacervates using different interlayer oils

A two-step emulsification prior to complex coacervation was employed to develop a co-encapsulation technology of hydrophilic and hydrophobic components for nutrition enhancement. Processing parameters of mononuclear ellipse-like microcapsules using gelatin and sodium carboxymethyl cellulose as wall materials were evaluated. The particle size and morphology of microcapsules and the encapsulation efficiency of L-ascorbic acid were significantly affected by the water-oil phase ratio and total biopolymer concentration. The L-ascorbic acid and quercetin co-encapsulated microcapsules with an average size of 65.26 µm showed good physical and chemical stability. The encapsulation efficiencies of L-ascorbic acid and quercetin were 69.91% and 88.21%, respectively. To predict the potential of functional lipids as hydrophobic carriers, microcapsules using soybean oil, olive oil, fish oil, and conjugated linoleic acid as interlayer oils were developed. The encapsulation efficiencies of hydrophobic compounds carried by different oils were similarly high (88.21-93.08%), whereas, hydrophilic ones carried by conjugated linoleic acid had the lowest encapsulation efficiency (32.54%). The interface tension results indicated that the interfacial stability was impaired by a competitive relation between conjugated linoleic acid and hydrophobic emulsifier at the interface, due to their structural similarity. These results provided the guidance for improving the quality of interlayer oils from microcapsules.

Formulation, Characterization, and In Vitro Mineral Absorption of Ficus Palmata Fruit Extract Nanoemulsion

OBJECTIVE

Loss of vital bioactive components of Ficus palmata fruit extract during food processing is a major issue. Therefore, to retain the antioxidant potential and to increase the mineral bioavailability, gum arabic stabilized nanoemulsion of Fig fruit extract was prepared.

METHOD

. Nanoemulsion was formulated using three different levels (1, 3, and 5%) of fig extract, however, to optimize the fig extract concentration, the amount of gum arabic and linoleic acid was kept constant.

RESULTS

The average droplet size of nanoemulsion was observed in the range of 22.88-37.87 nm, whereas the Fourier Transform Infrared (FTIR) Spectroscopy confirmed the presence of functional groups in the emulsion system. Also, increased ionic concentration significantly (p < 0.05) increased the average droplet size and zeta potential of nanoemulsion during storage. Increased shear rate and temperature unveiled a slight decrease in apparent viscosity of the nanoemulsion. Non-significant (p < 0.05) difference in TBA value confirmed the oxidative stability of the emulsion. Significantly (p < 0.05) higher mineral bioavailability for calcium was observed as compared to iron and zinc.

CONCLUSION

Our results manifested improved anti-oxidant activity, mineral bioavailability, and oxidative stability of Fig extract nanoemulsion, suggesting its potential use as a therapeutic alternative.

Fabrication and Characterization of a Microemulsion Stabilized by Integrated Phosvitin and Gallic Acid

The purpose of this work was to conjugate phosvitin (Pv) with gallic acid (GA) to explore a new emulsifier that had both good emulsifying properties and antioxidant activity. The Pv-GA complex was prepared at a GA concentration of 1.5 mg/mL with pH 9.0. The Pv-GA complex obtained was identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and characterized with infrared, ultraviolet, and fluorescence spectra. The emulsifying activity and stability of the Pv-GA complex were slightly improved, and antioxidant activities was significantly enhanced. Furthermore, the Pv-GA complex was used to load conjugated linoleic acid (CLA) for microemulsion preparation. Results showed that the Pv-GA complex could increase the viscosity and lipid antioxidant capacity of Pv-GA/CLA microemulsion. The Pv-GA/CLA microemulsion had remarkable emulsifying activity, emulsifying stability, pH, and thermal stability and poor salt stability.

Polysaccharides at fluid interfaces of food systems

Fabrication of next generation polysaccharides with interfacial properties is driven by the need to create high performance surfactants that operate at extreme environments, as for example in complex food formulations or in the gastrointestinal tract. The present review examines the behaviour of polysaccharides at fluid food interfaces focusing on their performance in the absence of any other intentionally added interfacially active components. Relevant theoretical principles of colloidal stabilisation using concepts that have been developed for synthetic polymers at interfaces are firstly introduced. The role of protein that in most cases is present in polysaccharide preparations either as contaminant or as integral part of the structure is also discussed. Critical assessment of the literature reveals that although protein may contribute to emulsion formation mostly as an anchor for polysaccharides to attach, it is not the determinant factor for the long-term emulsion stability, irrespectively of polysaccharide structure. Interfacial performance of key polysaccharides is also assessed revealing shared characteristics in their modes of adsorption. Conformation of polysaccharides, as affected by the composition of the aqueous solvent needs to be closely controlled, as it seems to be the underlying fundamental cause of stabilisation events and appears to be more important than the constituent polysaccharide sugar-monomers. Finally, polysaccharide adsorption is better understood by regarding them as copolymers, as this approach may assist to better control their properties with the aim to create the next generation biosurfactants.

Digital image colorimetric analysis for evaluating lipid oxidation in oils and its emulsion

Optical analytical images were captured by a digital camera, and lipid peroxidation was monitored using colorimetric determination. The Image-J method was shown to have comparable accuracy to the conventional titration (American Oil Chemists' Society) and UV-Vis spectroscopic methods. Over the PV range 3-14 meq.O₂/kg, a good correlation (R² = 0.9836) was found between the proposed method and UV-Vis method with an SD of ±0.0339 meq.O₂/kg. The range and accuracy of detection were determined from the changes in the Image-J intensity values. At equivalent PV, the limit of detection was 0.175 meq.O₂/kg and the limit of quantitation was 0.35 meq.O₂/kg. The proposed Image-J application can be used to develop fast and portable devices for monitoring peroxide values. These have potential applications in quality control for small-scale farmers and small and medium enterprises.

Whey protein isolate/gum arabic intramolecular soluble complexes improving the physical and oxidative stabilities of conjugated linoleic acid emulsions

Protein–polysaccharide intramolecular soluble complexes are proved to have superior emulsifying properties in stabilizing PUFAs-based emulsions.

Soy lipophilic protein nanoparticles as a novel delivery vehicle for conjugated linoleic acid

Soy lipophilic protein nanoparticles (LPP), which present a novel delivery vehicle for conjugated linoleic acid (CLA), were fabricated by ultrasonication of the soy lipophilic protein (LP), which exhibits unique characteristics including a high loading capacity, oxidation protection and a sustained releasing profile in vitro for CLA. The CLA-loaded LPP exhibited a mean diameter of 170 ± 0.63 nm and a loading capacity of 26.3 ± 0.40% (w/w). A coating of sodium caseinate (SC) on the surface improved the colloidal stability of the CLA-loaded LPP. This encapsulation conferred protection against the oxidation of CLA, by which the head space-oxygen consumption and hydrogen peroxide value were obviously decreased in comparison with the SC-encapsulated CLA and CLA alone. The delivery system enables a sustained releasing profile of CLA in a simulated gastrointestinal tract (GIT). These findings illustrate that the LPP could act as an effective delivery device for CLA, which could provide oxidation stability and a sustained release property.