Formulation and physicochemical stability of oil-in-water nanoemulsion loaded with α-terpineol as flavor oil using Quillaja saponins as natural emulsifier.

Alpha-terpineol (α-TOH) is a promising monoterpenoid detaining several biological activities. However, as a volatile molecule, the incorporation of α-TOH within formulated products poses several challenges related to its stability. In this sense, nanoencapsulation works as a key technology to protect the bioactivity of low molecular weight oils, like α-TOH, against environmental stresses (heat, light, and moisture), mitigating their susceptibility to degradation (oxidation and volatilization). Physical properties of encapsulated flavor/essential oil have been extensively reported, whereas there is a lack in the literature regarding their chemical stability, which is usually the main purpose of encapsulation. Thus, in this study, the physicochemical stability of the formulated oil-in-water nanoemulsion loaded with α-TOH stabilized with Quillaja saponins (QSs) as a natural emulsifier (α-TOH-QSs-NE) were tracked in a long-term (up to 280th day). Along with time, mean droplet diameter (MDD) and turbidity were used as a reference for physical parameters; while the chemical stability was monitored using gas chromatography analysis to quantify the mark content of α-TOH into the NE. Results indicated that α-TOH-QSs-NE was successfully formulated with a high-load amount of α-TOH (90 mg mL-1). α-TOH-QSs-NE showed great physicochemical stability regardless the storage-temperature (5 °C or 25 °C) up to 280th day, with no significant alterations in the MDD or turbidity, where c.a. 79% of the initial amount of the nanoemulsified α-TOH remained detectable in α-TOH-QSs-NEs, with no finding of degradation products. Thus, the data here disclosure may be useful for innovative application of α-TOH in foodstuffs.

Comprehensive study of α-terpineol-loaded oil-in-water (O/W) nanoemulsion: interfacial property, formulation, physical and chemical stability.

In this study, the interfacial ability of α-terpineol (α-TOH) was reported, followed by its trapping into oil-in-water (O/W) nanoemulsion as active-ingredient and the long-term observation of this nanosystem influenced by the storage-time (410-days) and temperature (5, 25, 50 °C). The results indicated that the α-TOH can reduce the interfacial tension on the liquid-liquid interface (ΔG°m = -1.81 KJ mol-1; surface density = 8.19 × 10-6 mol m-2; polar head group area = 20.29 Å2), in the absence or presence of surfactant. The O/W nanoemulsion loaded with a high amount of α-TOH (90 mg mL-1; 9α-TOH-NE) into the oil phase was successfully formulated. Among the physical parameters, the mean droplet diameter (MDD) showed a great thermal dependence influenced by the storage-temperature, where the Ostwald ripening (OR) was identified as the main destabilizing phenomena that was taking place on 9α-TOH-NE at 5 and 25 °C along with time. Despite of the physical instability, the integrity of both nanoemulsion at 5 °C and 25 °C was fully preserved up to 410th day, displaying a homogeneous and comparable appearance by visual observation. On contrary, a non-thermal dependence was found for chemical stability, where over 88% of the initial amount of the α-TOH nanoemulsified remained in both 9α-TOH-NE at 5 and 25 °C, up to 410th day. Beyond the key data reported for α-TOH, the importance of this research relies on the long-term tracking of a nanostructured system which can be useful for scientific community as a model for a robust evaluation of nanoemulsion loaded with flavor oils.

Microfibrillated cellulose from Argania spinosa shells as sustainable solid particles for O/W Pickering emulsions.

Microfibrillated cellulose (MFC) from Argan (Argania spinosa) shells was prepared by chemical purification of cellulose, then mechanical disintegration via high pressure homogenization was performed to isolate fibrils of cellulose. Chemical characterization of raw argan shell (AS-R), purified cellulose (AS-C), and argan shell MFC (AS-MFC) included FT-IR, XRD and NMR. Morphological characterization of AS-MFC was assessed using TEM. Next, the use of AS-MFC as oil-in-water (O/W) emulsions stabilizer was investigated. The particle concentration was observed to affect the long-term stability of the emulsions; high concentrations (0.5-1 % w/w) of AS-MFC resulted in emulsions that were thermodynamically stable during 15 days of storage, which was demonstrated by the droplet's size evolution. The suitable oil concentration for a maximum volume of emulsion using 1 % w/w AS-MFC was demonstrated. The results show that AS-MFC is able to stabilize 70 % w/w MCT oil without visual phase separation. Finally, CLSM shows the adsorption of AS-MFC at the oil-water interface and the formation of a 3D network surrounding oil droplets, confirming Pickering emulsion formation and stabilization.