Formation and stabilization of nanoemulsion-based vitamin E delivery systems using natural surfactants: Quillaja saponin and lecithin

Antimicrobial Nanoemulsion Formulation with Improved Penetration of Foliar Spray through Citrus Leaf Cuticles to Control Citrus Huanglongbing

Huanglongbing (HLB) is the most serious disease affecting the citrus industry worldwide to date. The causal agent, Candidatus Liberibacter asiaticus (Las), resides in citrus phloem, which makes it difficult to effectively treat with chemical compounds. In this study, a transcuticular nanoemulsion formulation was developed to enhance the permeation of an effective antimicrobial compound (ampicillin; Amp) against HLB disease through the citrus cuticle into the phloem via a foliar spray. The results demonstrated that efficiency of cuticle isolation using an enzymatic method (pectinase and cellulase) was dependent on the citrus cultivar and Las-infection, and it was more difficult to isolate cuticles from valencia orange (Citrus sinensis) and HLB-symptomatic leaves. Of eight adjuvants tested, Brij 35 provided the greatest increase in permeability of the HLB-affected cuticle with a 3.33-fold enhancement of cuticular permeability over water control. An in vitro assay using Bacillus subtilis showed that nanoemulsion formulations containing Amp (droplets size = 5.26 ± 0.04 nm and 94 ± 1.48 nm) coupled with Brij 35 resulted in greater inhibitory zone diameters (5.75 mm and 6.66 mm) compared to those of Brij 35 (4.34 mm) and Amp solution (2.83 mm) alone. Furthermore, the nanoemulsion formulations eliminated Las bacteria in HLB-affected citrus in planta more efficiently than controls. Our study shows that a water in oil (W/O) nanoemulsion formulation may provide a useful model for the effective delivery of chemical compounds into citrus phloem via a foliar spray for controlling citrus HLB.

Comparison of modified starch and Quillaja saponins in the formation and stabilization of flavor nanoemulsions

Modified starch (MS) and Quillaja saponins (QS) were compared to fabricate and stabilize orange oil nanoemulsions using microfluidization. Ester gum (EG) was incorporated in the oil phase at variable proportions (0-60%) as Ostwald ripening inhibitor and viscosity modifier. Optimal viscosity ratios of dispersed to continuous phase (ηd/ηc) were identified as 0.8-3.1 and 2.1-3.3 with MS and QS as emulsifier, respectively. QS was found superior to MS in fabricating nanoemulsion with smallest MDD of 69 nm and turbidity of 102 NTU at 0.05% of dispersed phase. With EG incorporated in the oil phase, QS stabilized nanoemulsions were stable during 2 weeks of storage at 23 °C; whereas MS stabilized nanoemulsions showed significant increases in MDD and turbidity. Zeta potential measurements showed QS imparted higher droplet charge (>-20 mV) than MS (<-5 mV) at pH 3.6 indicating MS stabilized nanoemulsions were destabilized by coalescence due to insufficient interfacial charge.

Nanoemulsion delivery systems for oil-soluble vitamins: Influence of carrier oil type on lipid digestion and vitamin D3 bioaccessibility

The influence of carrier oil type on the bioaccessibility of vitamin D3 encapsulated within oil-in-water nanoemulsions prepared using a natural surfactant (quillaja saponin) was studied using a simulated gastrointestinal tract (GIT) model: mouth; stomach; small intestine. The rate of free fatty acid release during lipid digestion decreased in the following order: medium chain triglycerides (MCT) > corn oil ≈ fish oil > orange oil > mineral oil. Conversely, the measured bioaccessibility of vitamin D3 decreased in the following order: corn oil ≈ fish oil > orange oil > mineral oil > MCT. These results show that carrier oil type has a considerable impact on lipid digestion and vitamin bioaccessibility, which was attributed to differences in the release of bioactives from lipid droplets, and their solubilization in mixed micelles. Nanoemulsions prepared using long chain triglycerides (corn or fish oil) were most effective at increasing vitamin bioaccessibility.

Degradation of Vitamin E in Nanoemulsions during Storage as Affected by Temperature, Light and Darkness

Vitamin E (VE) nanoemulsions confront physical instabilities and chemical degradation during processing and/or storage. Therefore, thermal stability and degradation kinetics of VE in nanoemulsions fabricated using low-energy emulsification method as a function of temperature under light and in the dark were studied. Nanoemulsions had small droplet diameter (≈110 nm). The thermal degradation of VE followed the first-order kinetics with samples heated at 75°C and above presenting the highest degradation rate and short half-life (5.22 min). The degradation of VE in long-term storage fitted the Weibull model with highest degradation in nanoemulsions stored under light at 40°C. However, VE retained in nanoemulsions after certain period of time might be boosted up when nanoemulsions are stored in the dark. Results showed that the physical stability tests alone are not enough to judge the stability of VE delivery systems, as the encapsulated VE might be lost during processing and storage.

Development of food-grade nanoemulsions and emulsions for delivery of omega-3 fatty acids: opportunities and obstacles in the food industry

Consumption of biologically active amounts of omega-3 fatty acids is linked to improved human health, which has partly been attributed to their important role in brain development and cardiovascular health. Western diets are relatively low in omega-3 fatty acids and many consumers turn to supplements or functional foods to increase their intake of these healthy lipids. Fish oil is one of the most widely used sources of omega-3 fatty acid for supplementation and has greater health benefits than plant sources because of its higher concentration of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The incorporation of omega-3 fatty acids into foods and beverages is often challenging due to their low water-solubility, poor oxidative stability, and variable bioavailability. Nanoemulsions offer a promising way to incorporate omega-3 fatty acids into liquid food systems like beverages, dressing, sauces, and dips. Nanoemulsions are colloidal dispersions that contain small oil droplets (r<100 nm) that may be able to overcome many of the challenges of fortifying foods and beverages with omega-3 fatty acids. The composition and fabrication of nanoemulsions can be optimized to increase the chemical and physical stability of oil droplets, as well as to increase the bioavailability of omega-3 fatty acids.