scholarly journals Comparative Study of Physicochemical Properties of Nanoemulsions Fabricated with Natural and Synthetic Surfactants

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 2002
Author(s):  
Karen Fuentes ◽  
Claudia Matamala ◽  
Nayaret Martínez ◽  
Rommy N. Zúñiga ◽  
Elizabeth Troncoso
Keyword(s):  
Physicochemical Properties ◽  
Droplet Size ◽  
Physical Stability ◽  
Droplet Size Distribution ◽  
Protein Isolate ◽  
Tween 20 ◽  
Synthetic Surfactant ◽  
Soy Lecithin ◽  
Food Grade ◽  
Droplet Size Distributions

This work aims to evaluate the effect of two natural (whey protein isolate, WPI, and soy lecithin) and a synthetic (Tween 20) emulsifier on physicochemical properties and physical stability of food grade nanoemulsions. Emulsions stabilized by these three surfactants and different sunflower oil contents (30% and 50% w/w), as the dispersed phase, were fabricated at two levels of homogenization pressure (500 and 1000 bar). Nanoemulsions were characterized for droplet size distribution, Zeta-potential, rheological properties, and physical stability. Dynamic light scattering showed that droplet size distributions and D50 values were strongly affected by the surfactant used and the oil content. WPI gave similar droplet diameters to Tween 20 and soy lecithin gave the larger diameters. The rheology of emulsions presented a Newtonian behavior, except for WPI-stabilized emulsions at 50% of oil, presenting a shear-thinning behavior. The physical stability of the emulsions depended on the surfactant used, with increasing order of stability as follows: soy lecithin < Tween 20 < WPI. From our results, we conclude that WPI is an effective natural replacement of synthetic surfactant (Tween 20) for the fabrication of food-grade nanoemulsions.

Influence of Composition of Emulsifier Blends on the Rheological Properties of Salad Dressing-Type Emulsions

2003 ◽  
Vol 9 (1) ◽  
pp. 53-63 ◽  
Author(s):  
M. A. Riscardo ◽  
J. M. Franco ◽  
C. Gallegos
Keyword(s):  
Rheological Properties ◽  
Size Distribution ◽  
Droplet Size ◽  
Physical Stability ◽  
Droplet Size Distribution ◽  
Egg Yolk ◽  
Tween 20 ◽  
Binary Blends ◽  
Sorbitan Monolaurate ◽  
Salad Dressing

This paper deals with the influence that composition of emulsifier blends exerts on the rheological properties of low-in-fat salad dressing-type emulsions. Binary blends of egg yolk and different types of amphiphilic molecules (low-molecular weight and macromolecules) were used in several proportions to stabilize emulsions by keeping constant the total amount of emulsifier. The different emulsifiers added to egg yolk were pea protein, sodium caseinate, polyoxyethylene(20)-sorbitan monolaurate (Tween 20) and sucrose distearate. Steady state flow tests and small-amplitude oscillatory measurements within the linear viscoelasticity region were carried out. Rheological tests were complemented with droplet size distribution measurements and observation of physical stability against creaming of these emulsions. It was pointed out that rheological properties, droplet size and physical stability of the emulsions studied depended on the weight ratio of emulsifiers in the binary blends, although the emulsifier total concentration remained constant, as well as the nature of the substance blended with egg yolk. These results have been explained on the basis of the relationship among rheological properties, droplet size distribution, continuous phase characteristics and interactions among different emulsifier molecules.

scholarly journals Whey Protein Isolate Microgel Properties Tuned by Crosslinking with Organic Acids to Achieve Stabilization of Pickering Emulsions

Foods ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1296
Author(s):  
Jéssica Thaís do Prado Silva ◽  
João Vitor Munari Benetti ◽  
Taís Téo de Barros Alexandrino ◽  
Odilio Benedito Garrido Assis ◽  
Jolet de Ruiter ◽  
...  
Keyword(s):  
Contact Angle ◽  
Organic Acids ◽  
Whey Protein ◽  
Physical Stability ◽  
Whey Protein Isolate ◽  
Protein Isolate ◽  
Pickering Emulsions ◽  
Food Grade ◽  
Oil Water ◽  
Coffee Oil

Whey protein isolate (WPI) can be used effectively to produce food-grade particles for stabilizing Pickering emulsions. In the present study, crosslinking of WPI microgels using organic acids (tannic and citric acids) is proposed to improve their functionality in emulsions containing roasted coffee oil. It was demonstrated that crosslinking of WPI by organic acids reduces the microgels’ size from ≈1850 nm to 185 nm and increases their contact angle compared to conventional WPI microgels, achieving values as high as 60°. This led to the higher physical stability of Pickering emulsions: the higher contact angle and smaller particle size of acid-crosslinked microgels contribute to the formation of a thinner layer of particles on the oil/water (O/W) interface that is located mostly in the water phase, thus forming an effective barrier against droplet coalescence. Particularly, emulsions stabilized by tannic acid-crosslinked WPI microgels presented neither creaming nor sedimentation up to 7 days of storage. The present work demonstrates that the functionality of these crosslinked WPI microgels can be tweaked considerably, which is an asset compared to other food-grade particles that mostly need to be used as such to comply with the clean-label policy. In addition, the applications of these particles for an emulsion are much more diverse as of the starting material.

Lagrangian stochastic microphysics at unresolved scales in turbulent cloud simulations

2020 ◽  
Author(s):  
Gustavo Abade ◽  
Marta Waclawczyk ◽  
Wojciech W. Grabowski ◽  
Hanna Pawlowska
Keyword(s):  
Droplet Size ◽  
Cloud Condensation Nuclei ◽  
Droplet Size Distribution ◽  
Cloud Microphysics ◽  
Cloud Droplets ◽  
Adiabatic Cooling ◽  
Subgrid Scales ◽  
The Mean ◽  
Microphysical Processes ◽  
Droplet Size Distributions

&lt;p&gt;Turbulent clouds are challenging to model and simulate due to uncertainties in microphysical processes occurring at unresolved subgrid scales (SGS). These processes include the transport of cloud particles, supersaturation fluctuations, turbulent mixing, and the resulting stochastic droplet activation and growth by condensation. In this work, we apply two different Lagrangian stochastic schemes to model SGS cloud microphysics. Collision and coalescence of droplets are not considered. Cloud droplets and unactivated cloud condensation nuclei (CCN) are described by Lagrangian particles (superdroplets). The first microphysical scheme directly models the supersaturation fluctuations experienced by each Lagrangian superdroplet as it moves with the air flow. Supersaturation fluctuations are driven by turbulent fluctuations of the droplet vertical velocity through the adiabatic cooling/warming effect. The second, more elaborate scheme uses both temperature and vapor mixing ratio as stochastic attributes attached to each superdroplet. It is based on the probability density function formalism that provides a consistent Eulerian-Lagrangian formulation of scalar transport in a turbulent flow. Both stochastic microphysical schemes are tested in a synthetic turbulent-like cloud flow that mimics a stratocumulus topped boundary layer. It is shown that SGS turbulence plays a key role in broadening the droplet-size distribution towards larger sizes. Also, the feedback on water vapor of stochastically activated droplets buffers the variations of the mean supersaturation driven the resolved transport. This extends the distance over which entrained CNN are activated inside the cloud layer and produces multimodal droplet-size distributions.&lt;/p&gt;

Dynamics of Intermittent Sprays

1999 ◽  
Author(s):  
Badih A. Jawad
Keyword(s):  
Droplet Size ◽  
Droplet Size Distribution ◽  
Sampling Technique ◽  
Size Distributions ◽  
Ambient Conditions ◽  
Spray Formation ◽  
Fuel Droplets ◽  
Liquid Immersion ◽  
Particle Sizer ◽  
Droplet Size Distributions

Abstract It is considered that droplet size distribution changes with time and space, since diesel fuel sprays are found to be transient and intermittent due to variations in ambient pressures. Therefore the obscuration signal (extinction of light due to particle field) obtained from a particle sizer for a single injection of fuel over the whole region of spray is necessary to determine the spray characteristics. Previous studies dealing with sprays have observed fuel droplets by use of the sedimentation tower method or liquid immersion sampling technique. However, in these technique droplets are usually sampled after spray formation is complete. The completion time of spray formation appears to vary with ambient conditions, thus making spray measurements under transient conditions during injection difficult. It is the objective of this paper to shine some light on the dynamics of spray motion, leading to a better understanding of the droplet size distributions.

scholarly journals Progress on Predicting the Breadth of Droplet Size Distributions Observed in Small Cumuli

2011 ◽  
Vol 68 (12) ◽  
pp. 2921-2929 ◽  
Author(s):  
Jennifer L. Bewley ◽  
Sonia Lasher-Trapp
Keyword(s):  
Droplet Size ◽  
Cloud Condensation Nuclei ◽  
Droplet Diameter ◽  
Droplet Size Distribution ◽  
Trade Wind ◽  
Droplet Growth ◽  
Size Distributions ◽  
Model Resolution ◽  
Modeling Framework ◽  
Droplet Size Distributions

Abstract A modeling framework representing variations in droplet growth by condensation, resulting from different saturation histories experienced as a result of entrainment and mixing, is used to predict the breadth of droplet size distributions observed at different altitudes within trade wind cumuli observed on 10 December 2004 during the Rain in Cumulus over the Ocean (RICO) field campaign. The predicted droplet size distributions are as broad as those observed, contain similar numbers of droplets, and are generally in better agreement with the observations when some degree of inhomogeneous droplet evaporation is considered, allowing activation of newly entrained cloud condensation nuclei. The variability of the droplet growth histories, resulting primarily from entrainment, appears to explain the magnitude of the observed droplet size distribution widths, without representation of other broadening mechanisms. Additional work is needed, however, as the predicted mean droplet diameter is too large relative to the observations and likely results from the model resolution limiting dilution of the simulated cloud.

Spatial distributions of cloud droplet size distributions from cloudbow observations measured with specMACS

2021 ◽  
Author(s):  
Veronika Pörtge ◽  
Tobias Kölling ◽  
Tobias Zinner ◽  
Linda Forster ◽  
Claudia Emde ◽  
...  
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Cloud Droplet ◽  
Droplet Size Distribution ◽  
Wide Field ◽  
Size Distributions ◽  
Vertical Profiles ◽  
Camera System ◽  
Cloud Droplet Size Distribution ◽  
Droplet Size Distributions

&lt;p&gt;The evolution of clouds and their impact on weather and climate is closely related to the cloud droplet size distribution, which is often represented by two parameters: the cloud droplet effective radius (reff) and the effective variance (veff). The droplet radius (reff) determines the radiative effect of clouds on climate. The effective variance is a measure of the width of the size distribution which is, for instance, important to understand the formation of precipitation or entrainment and mixing processes. We present an airborne remote-sensing technique to determine reff and veff from high-resolution polarimetric imaging observations of the LMU cloud camera system specMACS.&lt;/p&gt;&lt;p&gt;Recently the spectral camera system has been upgraded by a wide-field polarization resolving RGB camera which was operated for the first time on the HALO aircraft during the EUREC&lt;sup&gt;4&lt;/sup&gt;A campaign. The new polarimeter is ideally suited for observing the cloudbow - an optical phenomenon which forms by scattering of sunlight by liquid water cloud droplets at cloud top. The cloudbow is dominated by single scattering which has two implications: Its visibility is significantly enhanced in polarized measurements and its structure is sensitive to the cloud droplet size distribution at cloud top. This allows the retrieval of reff and veff by fitting the observed polarized cloudbow reflectances against a look-up table of pre-computed scattering phase functions.&lt;/p&gt;&lt;p&gt;The characteristics of the polarimeter are optimized for the measurement of the cloudbow. The wide field-of-view is key for observing the cloudbow (scattering angle 135&amp;#176; -165&amp;#176;) for a wide range of solar positions. Another advantage is the high spatial and temporal resolution which allows the study of small-scale variability of cloud microphysics at cloud top with a horizontal resolution of up to 20 m. Combining the polarimetric cloudbow technique with an existing stereographic retrieval of cloud geometry allows to derive vertical profiles of the droplet size distribution at cloud top. Observations of different EUREC&lt;sup&gt;4&lt;/sup&gt;A cloud fields are used to demonstrate the retrieval technique and to present first spatial distributions and vertical profiles of cloud droplet size distributions.&lt;/p&gt;

Comparing Simulation for Turbulent Dispersion and Coalescence of Droplets within a Spray with Two Models

2013 ◽  
Vol 353-356 ◽  
pp. 2473-2476
Author(s):  
Shao Yun Deng
Keyword(s):  
Droplet Size ◽  
Droplet Size Distribution ◽  
Computer Time ◽  
Turbulent Dispersion ◽  
Gas Flows ◽  
Wide Range ◽  
Order Of Magnitude ◽  
Time Required ◽  
And Shifts ◽  
Droplet Size Distributions

Lagrangian and Eulerian modelling approaches are compared for simulating turbulent dispersion and coalescence of droplets within a spray. Both models predict similar droplet dispersion rates and shifts in droplet size distribution due to coalescence within the spray, over a wide range of droplet and gas flows, and for sprays with different droplet size distributions at the nozzle exit. The computer time required for simulating coalescence within a steady axisymmetric spray is of a similar order of magnitude regardless of which formulation, Eulerian or Lagrangian, is adopted. However, the Lagrangian formulation is more practical in terms of the range of applicability and ease of implementation.

scholarly journals Physicochemical Properties and Cellular Uptake of Astaxanthin-Loaded Emulsions

Molecules ◽  
2019 ◽  
Vol 24 (4) ◽  
pp. 727 ◽  
Author(s):  
Xue Shen ◽  
Tianqi Fang ◽  
Jian Zheng ◽  
Mingruo Guo
Keyword(s):  
Whey Protein ◽  
Droplet Size ◽  
Cellular Uptake ◽  
Water Solubility ◽  
Entrapment Efficiency ◽  
Protein Isolate ◽  
Tween 20 ◽  
Natural Pigment ◽  
Physicochemical Stability ◽  
Potential Benefits

Astaxanthin, a natural pigment carotenoid, is well known for its potential benefits to human health. However, its applications in the food industry are limited, due to its poor water-solubility and chemical instability. Six different emulsifiers were used to prepare astaxanthin-loaded emulsions, including whey protein isolate (WPI), polymerized whey protein (PWP), WPI-lecithin, PWP-lecithin, lecithin, and Tween20. The droplet size, zeta potential, storage stability, cytotoxicity, and astaxanthin uptake by Caco-2 cells were all investigated. The results showed that the droplet size of the emulsions ranged from 194 to 287 nm, depending on the type of emulsifier used. The entrapment efficiency of astaxanthin was as high as 90%. The astaxanthin-loaded emulsions showed good physicochemical stability during storage at 4 °C. The emulsifier type had a significant impact on the degradation rate of astaxanthin (p < 0.05). Cellular uptake of astaxanthin encapsulated into the emulsions was significantly higher than free astaxanthin (p < 0.05). Emulsion stabilized with WPI had the highest cellular uptake of astaxanthin (10.0 ± 0.2%), followed, in order, by that with PWP (8.49 ± 0.1%), WPI-lecithin (5.97 ± 0.1%), PWP-lecithin (5.05 ± 0.1%), lecithin (3.37 ± 0.2%), and Tween 20 (2.1 ± 0.1%). Results indicate that the whey protein-based emulsion has a high potential for improving the cellular uptake of astaxanthin.

scholarly journals The Effect of High Shear Homogenization on Physical Stability of Emulsions

2016 ◽  
Vol 8 (4) ◽  
pp. 52 ◽  
Author(s):  
T. M. Silva ◽  
N. N. P. Cerize ◽  
A. M. Oliveira
Keyword(s):  
Droplet Size ◽  
Manufacturing Process ◽  
Stress Condition ◽  
Physical Stability ◽  
Droplet Size Distribution ◽  
Laser Diffraction ◽  
High Shear ◽  
High Shear Homogenization ◽  
Main Factors ◽  
Profile Change

<p class="03Abstract">Emulsions are thermodynamically unstable systems where droplet size is one of the main factors that affect its physical stability and consequently their quality. In this context, this work analyses the incorporation of a high shear homogenization step in the manufacturing process of an emulsion with the objective of maintaining its physical stability. In order to demonstrate the effects of this homogenization in the manufacturing process, the emulsion characterization was carried out by microscopy, rheology, laser diffraction and analytical photo-centrifugation techniques. The effect of high shear homogenization into the emulsion physical results was dependent on the speed applied to the homogenizer pump, with an effective 3600 rpm speed. There was no evidence of change on pH attributes and emulsion density, although there was a change in volumetric relationship between the droplet family presented in each sample, reducing the population of larger droplets to form a third family of intermediate droplets and increasing the volumetric proportion of the population of smaller droplets. This profile change in the droplet size distribution contributed to increased viscosity and emulsion without the presence of separation after it was submitted to the stress condition of temperature and agitation.</p>

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