Preparation and characterization of bioactive oils nanoemulsions: Effect of oil unsaturation degree, emulsifier type and concentration

Development of Saturated Fat Replacers: Conventional and Nano-Emulsions Stabilised by Lecithin and Hydroxylpropyl Methylcellulose

The combination of two emulsifiers, lecithin and hydroxypropyl methylcellulose (HPMC), into emulsions is an interesting strategy to design fat replacers in food matrices. The objective of this study was to investigate the effect of HPMC type and concentration on the formation, stability, and microstructure of conventional emulsions and nanoemulsions. Two different types of HPMC with low and high content of methyl and hydroxypropyl groups (HPMC-L and HPMC-H) were evaluated. The results showed that the molecular structure and concentration of HPMC play a major role in the viscoelastic behaviour, the gelation temperature, and the strength of gel formed. The firmness and work of shear of HPMC solutions increased significantly (p < 0.05) with increasing concentration. HPMC-L illustrated a more stable gel structure than the HPMC-H solution. Nanoemulsions showed lower moduli values, firmness, and work of shear than conventional emulsions due to the influence of high-pressure homogenization. A combination of lecithin and HPMC improved the physical and lipid oxidative stability of the emulsions, presenting a lower creaming index and thiobarbituric acid reactive substances (TBARS). In conclusion, HPMC-L at 2% w/w could be a suitable type and concentration combined with lecithin to formulate a saturated fat replacer that could mimic butter technological performance during food manufacturing operations.

Optimisation of the physicochemical stability of extra virgin olive oil-in-water nanoemulsion: processing parameters and stabiliser type

Extra virgin olive oil-in-water nanoemulsions stabilised with synthetic or clean label surfactants (Tween 20 or soy lecithin) was prepared using high-pressure homogenisation (HPH). The effect of HPH pressure and the number of cycles were assessed through response surface methodology to optimise homogenisation processing parameter. Mean droplet diameter (MDD), polydispersity index (PDI), thermal stability and oxidation stability of the resulting emulsions were evaluated. The results showed that the formation and stability of nanoemulsions can be affected by the homogenisation processing parameters (pressure and cycles) and the properties of surfactants (interfacial tension, viscoelasticity and molecule structure). Although MDD and PDI of Tween 20 stabilised nanoemulsions were influenced by homogenisation pressure and cycles, there was not a significant effect on lecithin-stabilised nanoemulsions. A homogenisation pressure of at least 400 bars produced Tween 20 stabilised nanoemulsion (MDD < 200 nm), whereas lecithin-stabilised nanoemulsion were obtained after high-speed homogenisation without using HPH. HPH at 400 bars for 1 cycle produced nanoemulsions with greater physical stability when using either Tween 20 or lecithin. Tween 20 stabilised nanoemulsion showed significantly higher (p < 0.05) thermal stability and lipid oxidative stability than lecithin-stabilised nanoemulsion. Following an optimisation study using regression modelling, the optimal homogenisation parameter for MDD of Tween 20 stabilised emulsion was found at pressure of 764 bars with 1 cycle, while lecithin-stabilised emulsion was found at pressure of 3 bars with 2 cycles. Overall, this study has important implications for optimising nanoemulsion production for potential application in the food industry.

Physical and Chemical Characterisation of Conventional and Nano/Emulsions: Influence of Vegetable Oils from Different Origins

The processes of oil production play an important role in defining the final physical and chemical properties of vegetable oils, which have an influence on the formation and characteristics of emulsions. The objective of this work was to investigate the correlations between oils’ physical and chemical properties with the stability of conventional emulsions (d > 200 nm) and nanoemulsions (d < 200 nm). Five vegetable oils obtained from different production processes and with high proportion of unsaturated fatty acids were studied. Extra virgin olive oil (EVOO), cold-pressed rapeseed oil (CPRO), refined olive oil (OO), refined rapeseed oil (RO) and refined sunflower oil (SO) were used in this study. The results showed that the physicochemical stability of emulsion was affected by fatty acid composition, the presence of antioxidants, free fatty acids and droplet size. There was a significant positive correlation (p < 0.05) between the fraction of unsaturated fatty acids and emulsion oxidative stability, where SO, OO and EVOO showed a significantly higher lipid oxidative stability compared to RO and CPRO emulsions. Nanoemulsions with a smaller droplet size showed better physical stability than conventional emulsions. However, there was not a significant correlation between the oxidative stability of emulsions, droplet size and antioxidant capacity of oils.

Pomegranate seed oil nanoemulsion enriched by α-tocopherol; the effect of environmental stresses and long-term storage on its physicochemical properties and oxidation stability

In this study, pomegranate seed oil (PSO) nanoemulsions loading different amounts of α-tocopherol (0-40%) were produced. The nanoemulsions were fabricated by ultra-sonication method and the influence of thermal treatment (20-90 °C), pH (2-8) and ionic strength (0-500 mM NaCl) were investigated on physicochemical properties of all treatments. Moreover, the oxidative stability and α-tocopherol degradation were also assessed on optimal enriched nanoemulsion formulation during 50-day storage. The droplet diameter, viscosity, antioxidant activity, encapsulation efficiency and loading capacity of optimal formulation were 37.5 nm, 514 cp, 92%, 3.45% and 92.5%, respectively. The peroxide value changed in the range of 4.5-5.3 and 6.7-10.5 meq O₂/kg in loaded and unloaded nanoemulsions, respectively. Transmission electron microscopy demonstrated spherical morphology of nanoemulsion droplets with diameter average of 40 nm. This study suggested that PSO nanoemulsion loading α-tocopherol could be introduced as delivery system with favorable features under severe environmental conditions.

Rambutan (Nephelium lappaceum) kernel olein as a non-hydrogenated fat component for developing model non-dairy liquid creamer: effect of emulsifier concentration, sterilization, and pH

In this work, the effects of the emulsifier concentration, sterilization process, and pH on the properties and stability of the model liquid creamer were evaluated. Applying diacetyl tartaric acid ester of mono- and diglycerides or DATEM at a concentration of 0.3% (w/w) in the presence of 2% (w/w) sodium caseinate produced stable model liquid creamers (10% (w/w) rambutan kernel olein) with a small particle size (Z-average ≈ 200 nm) and a narrow size distribution range (PDI < 0.24). These creamers were stable regarding creaming and coalescence, having non-flocculated particles and a constant flow behavior index (n) after sterilization using autoclaving (121 °C, 1.1 bar for 15 min) and during storage for 150 days at 25 °C. The model liquid creamers were unstable at pH values near the isoelectric point of caseinate (pH 4-5). However, these were stable after mixing with hot coffee solutions based on no observed feathering or sedimentation. The whitening performance of the model liquid creamers compared well with commercial ones. Non-hydrogenated fat-based model non-dairy liquid creamer was successfully formulated using rambutan kernel olein as a fat component. The results obtained in this study are useful for the possible application of fractionated rambutan kernel fat in food products.

Modeling the Effect of Composition on Formation of Aerosolized Nanoemulsion System Encapsulating Docetaxel and Curcumin Using D-Optimal Mixture Experimental Design

The synergistic anticancer effect of docetaxel (DTX) and curcumin (CCM) has emerged as an attractive therapeutic candidate for lung cancer treatment. However, the lack of optimal bioavailability because of high toxicity, low stability, and poor solubility has limited their clinical success. Given this, an aerosolized nanoemulsion system for pulmonary delivery is recommended to mitigate these drawbacks. In this study, DTX- and CCM-loaded nanoemulsions were optimized using the D-optimal mixture experimental design (MED). The effect of nanoemulsion compositions towards two response variables, namely, particle size and aerosol size, was studied. The optimized formulations for both DTX- and CCM-loaded nanoemulsions were determined, and their physicochemical and aerodynamic properties were evaluated as well. The MED models achieved the optimum formulation for DTX- and CCM-loaded nanoemulsions containing a 6.0 wt% mixture of palm kernel oil ester (PKOE) and safflower seed oils (1:1), 2.5 wt% of lecithin, 2.0 wt% mixture of Tween 85 and Span 85 (9:1), and 2.5 wt% of glycerol in the aqueous phase. The actual values of the optimized formulations were in line with the predicted values obtained from the MED, and they exhibited desirable attributes of physicochemical and aerodynamic properties for inhalation therapy. Thus, the optimized formulations have potential use as a drug delivery system for a pulmonary application.