Hybrid oil-in-water emulsions applying wax(lecithin)-based structured oils: Tailoring interface properties

Fabrication of interfacial crystallized oleogel emulsion for quercetin delivery with enhanced environmental stability and bioaccessibility

BACKGROUND

Quercetin is a flavonoid compound with numerous bioactivities. However, the low solubility, easy degradation and low bioaccessibility limit its application. In this study, a novel interfacial crystallized oleogel emulsion was fabricated, where beeswax was used as the oleogelator, for quercetin encapsulation with enhanced stability and bioaccessibility.

RESULTS

The process of interfacial crystallization was investigated using interfacial rheology and polarized microscopy, with a positive correlation between crystal density and beeswax content in the oil phase. Emulsion stability was directly linked to beeswax concentration in the oil phase, with 100 mg g-1 showing enhanced stability under storage, UVB light exposure and ionic conditions. Beeswax addition significantly increased the quercetin loading capacity of the emulsion; particularly, at a 200 mg g-1 beeswax concentration, the loading capacity was improved by 285.55%, and the environmental stability was enhanced against UV light and Ca2+. Ultimately, in vitro simulated digestion experiment indicated improved bioaccessibility of quercetin.

CONCLUSIONS

This strategy significantly enriched the formulation of oleogel emulsion and its potential applications in delivering bioactive ingredients with high environmental vulnerability. © 2024 Society of Chemical Industry.

Physicochemical Characterization, Rheological Properties, and Antimicrobial Activity of Sodium Alginate-Pink Pepper Essential Oil (PPEO) Nanoemulsions

Essential oils (EOs) have antimicrobial properties, but their low solubility in water and strong flavor pose challenges for direct incorporation into food, as they can negatively impact organoleptic properties. To overcome these issues, strategies such as oil-in-water (O/W) nanoemulsions have been developed to improve EO dispersion and protection while enhancing antimicrobial efficacy. The objective of this study was to create sodium alginate-pink pepper essential oil (PPEO) nanoemulsions using microfluidization. Various formulations were assessed for physicochemical, physical, and antimicrobial properties to evaluate their potential in food applications. The microfluidized emulsions and nanoemulsions had droplet sizes ranging from 160 to 443 nm, polydispersity index (PdI) ranging from 0.273 to 0.638, and zeta potential (ζ) ranging from -45.2 to 66.3 mV. The nanoemulsions exhibited Newtonian behavior and remarkable stability after 20 days of storage. Antimicrobial testing revealed effectiveness against Staphylococcus aureus and Listeria monocytogenes, with minimum inhibitory concentrations (MIC) of 200 µg/mL for both microorganisms and minimum bactericidal concentrations (MBC) of 800 µg/mL and 400 µg/mL, respectively, proving that encapsulation of PPEO in nanoemulsions significantly increased its antibacterial activity. These results present the possibility of using PPEO nanoemulsions as a more effective natural alternative to synthetic preservatives in food systems.

Oleogel Systems for Chocolate Production: A Systematic Review

In response to the growing demand for healthier food options, this review explores advances in oleogel systems as an innovative solution to reduce saturated fats in chocolates. Although appreciated for its flavor and texture, chocolate is high in calories, mainly due to cocoa butter (CB), which is rich in saturated fats. Oleogels, three-dimensional structures formed by structuring agents in edible oils, stand out in terms of mimicking saturated fats' physical and sensory properties without compromising the quality of chocolate. This study reviews how oleogels could improve chocolate's stability and sensory quality, exploring the potential of pectin-rich agro-industrial by-products as sustainable alternatives. It also explores the need for physicochemical evaluations of both oleogel and oleogel-based chocolate.

External factors affecting the linear and nonlinear rheological behavior of oleogel-based emulsions

This study reported oleogel-based emulsions (OGEs, W/O) stabilized by carnauba wax. The effects of different external factors (heating temperature, crystallization temperature, and shear application during crystallization) on the microstructure and linear/nonlinear rheological properties of OGEs were investigated. Microstructural observation suggested that the OGEs had a uniform droplet distribution, and the carnauba wax crystals trapped oil in the continuous phase. The gelatinized oil phase allowed the OGEs to have a solid appearance and typical yielding behavior. The small amplitude oscillation shear analysis showed that lower heating temperature, higher crystallization temperature, and suitable shear application resulted in a stronger, more stable, and tighter packed network structure and better resistance to deformation of the OGEs. For nonlinear behavior, the elastic dominant behavior of OGEs transformed into viscous dominant behavior at large strain amplitudes, accompanied by more energy dissipation, strain stiffening, and a transition from shear thickening to shear thinning.

Physicochemical and Functional Properties of Citrullus mucosospermus, Citroides, and Moringa oleifera Seeds' Hydrocolloids

Hydrocolloids form gel-like structures when dispersed in water and have garnered significant attention for their diverse applications in food, pharmaceuticals, and other industries. The extraction of hydrocolloids from natural sources, such as seeds, presents an intriguing avenue due to the potential diversity in composition and functionality. Utilising seeds from Citrullus lanatus mucosospermus, lanatus citroides, and Moringa aligns with the growing demand for natural and sustainable ingredients in various industries. This research investigated hydrocolloids extracted from Citrullus mucosospermus (CMS), lanatus citroides, and Moringa oleifera seeds, highlighting their versatile physicochemical and functional attributes. Hydrocolloids were extracted from the seeds and subjected to analysis of their proximate composition, particle size distribution, and interfacial tension using the hot water extraction method. Protein content variation was observed among the raw oilseed (CMS, Citroides, and Moringa oleifera) flours. The protein content of the hydrocolloids surpassed that of raw oilseeds, significantly enhancing the amino acid profile. Furthermore, the hydrocolloid ash contents ranged from 4.09% to 6.52% w/w dry weight, coupled with low fat levels. The particle size distribution revealed predominantly fine particles with a narrow size distribution. All three hydrocolloids demonstrated remarkable oil- and water-holding capacities, highlighting their suitability for efficient stabilisation and emulsification in food formulations. These findings suggest the potential utilisation of these hydrocolloids as valuable ingredients across a spectrum of applications, encompassing food, pharmaceuticals, and industry, thus contributing to the development of sustainable and functional products. The unique attributes presented herein mark a noteworthy advancement in the understanding and application of novel hydrocolloids from CMS, Citroides, and Moringa oleifera.

Stabilization of oil-in-water high internal phase emulsions with octenyl succinic acid starch and beeswax oleogel

High internal phase emulsions (HIPEs) based on beeswax (BW) oleogels and octenyl succinic acid starch (OSA starch) were prepared by a facile one-step method. Effects of the oleogelation of internal phase on the formation, stability and functionality of the HIPEs were investigated. OSA starch absorbed at the interface allowed high surface charge (|ζ| > 25 mV) of the droplets, and small droplet size (d ≈ 5 m). Microstructural observation suggested that the HIPEs were of O/W type with droplets packed tightly. With the increase in BW content (0-4 %), the particle size (4-7 μm) and ζ-potential (-25 ~ -30 mV) of the HIPEs were first decreased and then increased. Stability analysis revealed that the addition of BW effectively improved emulsion stability against centrifugation, freeze-thawing, changes in pH and ionic strength, and the HIPE with 2 % BW presented the best stability. Rheological tests indicated that the HIPEs with higher content of BW exhibited higher storage modulus, solid-like properties, and shear thinning behaviors. Creep-recovery results implied that the oleogelation enhanced the structure of HIPEs and improved the deformation resistance of the systems. When subjected to light and heat, oleogel-in-water HIPEs showed advantages in protecting β-carotene from degradation, and β-carotene in the HIPEs with 2 % BW had the lowest degradation rate. These findings suggested that gelation of oil phase could improve the stability of HIPEs and the encapsulation capability, which would be meaningful for the development of novel healthy food.

Tailoring a novel ovalbumin emulsion gel for stability improvement and functional properties enhancement: Effect of oil phase structure changes by beeswax

This study aimed to form a novel emulsion gel (EG) through structured oil phase of natural component beeswax (BW), together with ovalbumin (OVA), and to investigate the mechanism of its formation and stabilization in terms of microstructure and processing properties. Confocal laser scanning microscopy (CLSM) demonstrated that the EG formed a continuous double network structure since the superior crystallinity of the oil phase was given by BW. Fourier transform infrared spectroscopy (FT-IR) illustrated that the acylation of the phenolic hydroxyl group in BW with an amide bond in OVA, increased the hydrogen bonding of EG. Furthermore, the immobilization of the oil phase results in better thermal and freeze-thaw stability of EG. Finally, EG was used as a curcumin delivery system, and the presence of BW significantly improved its adaptability to multiple environmental factors. In summary, our study would provide valuable ideas for developing the design of finely structured functional food.

Construction of interfacial crystallized oleogel emulsion with improved thermal stability

In this study, we reported a facile strategy to produce an interfacial crystallized oleogel emulsion for improved thermal stability. The interfacial crystallization of ceramide (non-interfacial active oleogelator) was achieved by addition of a surface active compound, which was demonstrated by interfacial rheology tests and polarized light microscopy. For successfully prepared interfacial crystallized emulsions, smaller particle size was observed when the gelator concentration was lower. However, better thermal stability was achieved when oleogelator concentration was higher than 1 wt%. Results from differential scanning calorimetry, X-ray diffraction and Fourier transform infrared spectroscopy suggested that the interfacial adsorption of ceramide was due to its co-crystallization with the emulsifier driven by hydrogen bonds formed by multiple sites. It provided appropriate crystallinity and steric repulsion for oleogel emulsions against oil droplet coalescence during heating process. This strategy greatly enriches oleogel emulsion formulations and their potential applications in food products involved with thermal treatment.

Oil-in-water emulsion gels stabilized with cellulosic polymers and chitosan: Themorheological and physical-chemical evaluation

This research evaluated the use of different polymer ratios, hydroxypropyl methylcellulose (HPMC) and methylcellulose (MC) with chitosan (CHI), in the production of emulgel by emulsification. The concentration was fixed at 2 % (w/v) for all polymers. 60/40 sunflower oil-in-water emulgels were made with a cellulosic polymer:chitosan ratio of (80:20), (70:30), and (60:40), respectively. The objective was to study how different proportions of a cellulosic polymer combined with chitosan can affect the stability, microstructure, and rheology of the emulgels to be used as potential oil carrier systems. Droplet size and microscopy results show oil-in-water (O/W) emulgels, and their interface was stabilized by mixing polymeric pairs, HPMC:CHI or MC:CHI. In the thermal analysis, it was identified in the entire temperature range studied (5 to 85 °C) that both emulgels, HPMC:CHI and MC:CHI, were presented as gels (G' > G″). Thus, the addition of CHI to the systems modified their gelling behavior. Microscopy revealed that the emulsions at the 7th and 10th week of storage showed similar characteristics to the fresh emulsion. Therefore, these results indicate that the emulgels present good thermal resistance, the predominance of elastic behavior, and can retain high concentrations of oil in their structure (96 to 99 %).

Novel Formulation of Bigel-Based Vegetable Oil Spreads Enriched with Lingonberry Pomace

In this study, bigel-based vegetable oil spreads with lingonberry pomace addition were prepared. The impact of gelatin, agar and collagen was examined as structuring agents as was the effect of lecithin concentration (0.5, 1.0, 1.5%). Prepared systems were evaluated by physical and chemical stability and structural and rheological properties. It was found that all bigel formulations were self-standing with no signs of phase separation at ambient temperature immediately after preparation and after two weeks of storage at 4 °C temperature. The lingonberry pomace addition affected grainy structure formation with homogenous and uniform distribution of fiber particles throughout the bigel matrix and it also altered the colour of the bigels toward a purple-red. Texture, rheological properties and colour of the spread formulations were affected by the type of the structuring agent as well as the lecithin concentration. The presence of the lingonberry pomace enhanced the resistance of the bigel samples to the oxidation process and it was confirmed by the DPPH^• inhibition, peroxide value and oxipress test. Overall, the formulated bigel-based spreads could be beneficial and had a potential application as healthier fat spreads and be a source of dietary fibers (11 g of fibre per 100 g of the spread).