Formulation and optimization of emulsions based on bitter fennel essential oil and EO/BO block copolymer surfactant

Progress of nanopreparation technology applied to volatile oil drug delivery systems

Traditional Chinese medicine volatile oil has a long history and possesses extensive pharmacological activity. However, volatile oils have characteristics such as strong volatility, poor water solubility, low bioavailability, and poor targeting, which limit their application. The use of volatile oil nano drug delivery systems can effectively improve the drawbacks of volatile oils, enhance their bioavailability and chemical stability, and reduce their volatility and toxicity. This article first introduces the limitations of the components of traditional Chinese medicine volatile oils, discusses the main classifications and latest developments of volatile oil nano formulations, and briefly describes the preparation methods of traditional Chinese medicine volatile oil nano formulations. Secondly, the limitations of nano formulation technology are discussed, along with future challenges and prospects. A deeper understanding of the role of nanotechnology in traditional Chinese medicine volatile oils will contribute to the modernization of volatile oils and broaden their application value.

Effect of sesamol on the physical and chemical stability of plant-based flaxseed oil-in-water emulsions stabilized by proteins or phospholipids

Plant-based polyphenols are increasingly being explored as functional ingredients in emulsified food systems. In this study, the effects of sesamol on the physical and chemical stability of flaxseed oil-in-water emulsions stabilized by either phospholipids (sunflower) or proteins (whey or pea) were investigated. In the absence of sesamol, the protein-based emulsions displayed better physical stability than the phospholipid-based ones, which was related to their smaller particle diameter and higher particle charge. For the phospholipid-based emulsions, sesamol addition did not improve their physical stability, but it did inhibit lipid oxidation. In particular, it decreased the formation of secondary oxidation products, with a 65% reduction in TBAR formation compared to the control after 8 days of storage. For the protein-based emulsions, sesamol addition reduced particle aggregation and inhibited lipid oxidation, reducing the secondary oxidation products by around 85% after 19 days of storage. The inhibitory efficiency of sesamol in the pea protein-based emulsions was comparable to that in the whey protein-based ones. The effects of sesamol on the physical and chemical stability of the emulsions were related to its partitioning between the oil, water, and interfacial layers. This study suggests that adding sesamol to plant-based emulsions may improve their physical and chemical stability, thereby extending their shelf life.

Milk fat nanoemulsions stabilized by dairy proteins

Droplet size, polydispersity, physical and polymorphic stability of milk fat nanoemulsions produced by hot high-pressure homogenization and stabilized by whey protein isolate (WPI pH 4.0 or 7.0) or sodium caseinate (NaCas pH 7.0) were evaluated for 60 days of storage at 25 °C. Smaller droplets were observed for the NaCas pH 7.0 nanoemulsion, which also showed a lower polydispersity index, resulting in a stable emulsified system for 60 days. On the other hand, the nanoemulsion with bigger droplet size (WPI pH 4.0) showed reduced stability, probably due to the pH near the isoelectric point of the whey proteins. The nanostructured milk fat exhibited the same melting behavior as the bulk milk fat, with a balance between liquid and crystallized fat, and crystals in polymorphic form β'. This could be an advantage concerning the application of the system for delivery of bioactive compounds and improvement of the sensory properties of fat-based food. In summary, nanoemulsions stabilized by NaCas (pH 7.0) showed higher kinetic stability over the storage time, which from a technological application point of view is a very important factor in the food industry.

Strategies for reducing Ostwald ripening phenomenon in nanoemulsions based on thyme essential oil

BACKGROUND

White thyme essential oil, which can be incorporated in clean-label and food emulsion-based products, is a natural antimicrobial agent. However, emulsions containing essential oils commonly undergo Ostwald ripening as the main destabilization process. The main objective of this work was to evaluate various strategies for the inhibition of Ostwald ripening so as to develop stable nanoemulsions containing white thyme essential oil as food preservative and Kolliphor EL as surfactant.

RESULTS

In a first approach, the influence of the surfactant/dispersed phase ratio and the number of cycles through a microfluidizer on droplet size distribution was evaluated. Unfortunately, these emulsions underwent Ostwald ripening, which was demonstrated by the application of the Lifshitz-Slyozov-Wagner theory. In order to reduce this destabilization mechanism, two different techniques based on the modification of the formulation (addition of rosin gum or Aerosil COK84) were analysed using laser diffraction and multiple light scattering techniques. The addition of rosin gum inhibited the Ostwald ripening mechanism, but only partially. Conversely, the incorporation of Aerosil COK84 to the continuous phase led to a gel-like rheological behaviour which seemed to practically avoid Ostwald ripening.

CONCLUSIONS

Aerosil particles cover the droplets and form a three-dimensional network suggesting a Pickering stabilization, which was confirmed using transmission electronic microscopy. The results confirmed the role of Aerosil COK84, not only as a thickener or gelling agent, but also as an Ostwald ripening inhibitor. © 2019 Society of Chemical Industry.

Food-Grade Nanoemulsions: Preparation, Stability and Application in Encapsulation of Bioactive Compounds

Nanoemulsions have attracted significant attention in food fields and can increase the functionality of the bioactive compounds contained within them. In this paper, the preparation methods, including low-energy and high-energy methods, were first reviewed. Second, the physical and chemical destabilization mechanisms of nanoemulsions, such as gravitational separation (creaming or sedimentation), flocculation, coalescence, Ostwald ripening, lipid oxidation and so on, were reviewed. Then, the impact of different stabilizers, including emulsifiers, weighting agents, texture modifiers (thickening agents and gelling agents), ripening inhibitors, antioxidants and chelating agents, on the physicochemical stability of nanoemulsions were discussed. Finally, the applications of nanoemulsions for the delivery of functional ingredients, including bioactive lipids, essential oil, flavor compounds, vitamins, phenolic compounds and carotenoids, were summarized. This review can provide some reference for the selection of preparation methods and stabilizers that will improve performance in nanoemulsion-based products and expand their usage.

Production of thymol nanoemulsions stabilized using Quillaja Saponin as a biosurfactant: Antioxidant activity enhancement

Thymol oil-in-water nanoemulsions as a potential natural alternative for synthetic antioxidant agents were developed. The nanoemulsions were formulated using Quillaja Saponin bio-surfactant and green solvents including high oleic sunflower oil (HOSO), tricaprylin (TC), and cinnamaldehyde (CA). The 4% thymol nanoemulsions containing TC and HOSO remained stable during long-term storage (at least 30 d). The antioxidant activity (AA) of free thymol and thymol nanoemulsions was compared with butylated hydroxytoluene (BHT) and ascorbic acid. The results obtained from DPPH, FRAP, and CUPRAC antioxidant assays showed a substantial improvement (p < 0.05) of the AA of free thymol through emulsification. The outcomes from the AA of the nanoemulsions in raw chicken breast meat measured by the TBARS assay revealed a significant improvement (p < 0.05) of the AA when thymol was encapsulated. These nanoemulsions may be applicable in the food industry as well as in cosmetic and health care products.