Oil Droplet Size Research Articles

Exploring the influence of sweet potato powder on the physicochemical characteristics, oxidative potential and sensory perception of mayonnaise

SummaryReduced fat mayonnaise was prepared by substituting oil with sweet potato powder at concentrations of 2%, 4% and 6%. The changes in physicochemical, oxidative, rheological, microbial and organoleptic properties of functional reduced fat mayonnaise were investigated. The results revealed that sweet potato powder significantly improved the antioxidant activity (2.63–31.6%), rheological attributes, nutritional content and shelf life stability of mayonnaise during the storage time of 21 days. Rheological evaluation illustrated the stabilisation of samples with the addition of sweet potato powder, with a significant reduction in oil droplet size (6.78–2.16 μm) and an increase in firmness (0.941–1.84 N) and adhesiveness (41.21–76.78 × 10−3 Nm). Emulsion stability (93.3–99.2%) was significantly (P < 0.05) enhanced by supplementation with sweet potato powder. The presence of carotenoids in sweet potato improved colour and increased the L* (73.4%) and b* (31.4%) values. Preliminary sensory evaluation demonstrated that taste, texture, mouthfeel and overall acceptability were perceived better in the samples supplemented with sweet potato powder. Our findings suggest that sweet potato powder can be a nutrient enhancer and a considerable alternative to synthetic antioxidants and stabilisers for oil‐in‐water food emulsions.

Unraveling the emulsifying activity of bio-based ionic liquids in the formation and stabilization of oil-in-water emulsions

Bio-based ionic liquids (ILs), especially those derived from fatty acids (FAs) have been considered promising compounds for the agri-food and bioproduct industries, due to their sustainable appeal, possibly low or non-toxic effect and the nutritional value of FAs. However, studies have been mainly focused on the use of ILs as greener solvents. This work investigated the application of ILs derived from FAs and diethanolamine as emulsifiers to form and stabilize oil-in-water emulsions using ultraturrax (PM) and high-pressure homogenization (H). The influence of the IL type obtained from different FAs (stearic or oleic acids), and vegetable oil type (sunflower or olive oil) and concentration (30:70 or 70:30, oil:water phase ratio) on the formation and stabilization of emulsions was evaluated. This study was focused on the zeta potential of IL aqueous solutions in different pH conditions, interfacial tension between vegetable oils and IL aqueous solutions at different concentrations, kinetic stability, droplet size and size distribution, optical microscopy, viscosity profile and rheological behavior of the emulsions. ILs presented highly negative ZP charge (−12.97–−74.81), high emulsifying ability at low concentrations (1 %) and led to emulsions with high kinetic stability (>30 days). The electrostatic stabilization mechanism may predominate over the steric in IL-based emulsions. The stabilization of emulsions with ILs was associated to lower oil droplet size (D3,2 = 0.60–4.09 µm, D4,3 = 0.95–9.91 μm) and emulsion viscosity (4.8 mPa·s-1.13 Pa·s), which were related to the IL molecular structure, oil type and concentration, and process. Emulsions prepared with stearic-based IL and sunflower oil by PM+H presented higher kinetic stability. The proposed ILs are presented as highly effective emulsifiers with potential application in the agri-food, pharmaceutical and cosmetic industries.

Influence of Nozzle Geometry and Scale-Up on Oil Droplet Breakup in the Atomization Step during Spray Drying of Emulsions

Spray drying of oil-in-water emulsions is a widespread encapsulation technique. The oil droplet size (ODS) significantly impacts encapsulation efficiency and other powder properties. The ODS is commonly set to a specific value during homogenization, assuming that it remains unchanged throughout the process, which is often inaccurate. This study investigated the impact of atomizer geometry and nozzle dimensions on oil droplet breakup during atomization using pressure-swirl atomizers. Subject of the investigation were nozzles that differ in the way the liquid is set in motion, as well as different inlet port and outlet orifice dimensions. The results indicate that nozzle inlet port area may have a significant impact on oil droplet breakup, with x90,3 values of the oil droplet size distribution decreasing from 5.29 to 2.30 µm with a decrease of the inlet area from 2.0 to 0.6 mm. Good scalability of the findings from pilot to industrial-scale was shown using larger nozzles. A simplified theoretical model, aiming to predict the ODS as a function of calculated shear rates, showed reasonable agreement to the experimental data for different atomization pressures with coefficients of determination of up to 0.99. However, it was not able to predict the impact of different nozzle dimensions, most likely due to changes in flow characteristics. These results suggest that the stress history of the oil droplets might have a larger influence than expected. Further studies will need to consider other zones of high stress in addition to the outlet orifice.

Performance of new synthesized emulsifiers in ecofriendly metal cutting fluid formulations

This study aims to prepare mono and gemini nonionic emulsifiers differing in HLB to utilize in formulated metal cutting fluids. Also, the cationic gemini surfactant (GCS) was prepared and applied as a corrosion inhibitor and biocide in the formulations. FT-IR and NMR confirmed the chemical structure of the prepared compounds. Different oil package formulations were prepared by adding different trial concentrations of the additives (emulsifier, corrosion inhibitor, coupling agent, and biocide) to the eco-friendly vegetable oil (castor oil). Standard procedures were performed to assess the stability of the formulated base oil packages. Six Formulas demonstrated the greatest oil stability. Oil in water emulsions with varying formulated oil ratios (5–15 wt%) were prepared. A standard test was carried out to evaluate their performance as emulsion stability. It’s been demonstrated that Formulas II and V produced stable emulsions. The wettability alteration of formulas II and V on different metal surfaces was evaluated. The droplet size of formulated castor oil in water was determined via DLS. Corrosion test and tribological properties were also performed. The findings of this study indicate that Formula V is a good choice as a renewable addition for enhancing a variety of performance characteristics of the water-based cutting fluid.

The Preparation of Curcumin-Loaded Pickering Emulsion Using Gelatin-Chitosan Colloidal Particles as Emulsifier for Possible Application as a Bio-Inspired Cosmetic Formulation.

In the field of preparing cosmetic formulations, recent advances recommend the usage of excipients derived from biocompatible materials. In this context, the present study aimed to prepare and characterize the curcumin-loaded Pickering emulsion for possible applications in cosmetic formulation. The coconut oil which is often the component of skin care formulations is used as the oily phase. Curcumin, which is well known for absorbing solar radiation, is expected to work synergistically with coconut oil towards improving the sun protection factor (SPF) of the formulation. Additionally, curcumin can also protect the intracellular components through its well-known antioxidant mechanisms. The Pickering emulsion of coconut oil into water was prepared using the composite colloidal particles derived from β-carboxymethyl chitosan (CMC) and Gelatin-A (GA) as the emulsifying agent. The reaction conditions in terms of the weight ratios of CMC and GA, the pH of the reaction medium, the oil volume fraction, and the homogenization speed were optimized to obtain the most stable Pickering emulsion. The obtained systems were physico-chemically characterized by dynamic light scattering, zeta potential, optical microscopy, and rheometric measurements. The final CMC-GA-stabilized emulsion demonstrated an oil droplet size of 100 µm and a SPFspectrophotometric (290-320 nm) value of 8.5 at a curcumin loading of 4 mg/mL. Additionally, the final formulation facilitated the uptake of curcumin into fibroblast (WI26) cells under in vitro conditions. Together, the investigation demonstrates a bio-inspired approach to prepare a curcumin-loaded green Pickering emulsion using biocompatible pharmaceutical grade excipients, which may find utility in cosmetic applications.

Physicochemical and antimicrobial properties of soy protein isolate films incorporating high internal phase emulsion loaded with thymol

Oil-in-water (O/W) high internal phase (HIP) emulsion was prepared to investigate its effects on the physicochemical properties and antimicrobial properties of soy protein isolate (SPI)-based films. The particle size and migration degree of oil droplets in the SPI film-forming solution with HIP emulsion and the films were lower than those with conventional O/W emulsion or oil. The SPI-based emulsion films with HIP emulsion containing 30 % oil had the lowest water vapor permeability (1.15 × 10−10 g·m−1·s−1·Pa−1), glass transition temperature (40.93 °C) and tensile strength (4.47 MPa), and the highest transparency value (12.87) and elongation at break (160.83 %). The antimicrobial test of the SPI-based emulsion films loaded with thymol showed that the thymol encapsulation efficiency, sustained release effect, and growth inhibition effect on microbes were higher for the films with HIP emulsion than those for the films with O/W emulsion or oil.

Experimental investigation of free-rising characteristics of spilled oil droplets in natural waters

This work focuses on investigating the dynamics of different types of oil droplets rising freely in water columns. Fifteen different types of oils were selected to cover most of the conventional oils. The particle size range of the study is 1.41∼13.58 mm, which can cover the largest oil droplet size that may occur in the real environment. Investigation results show that oil droplet characteristics greatly influence the dynamics process of oil droplet motion. The characteristics which play a dominant role will change as the oil droplet particle size increases. Meanwhile, a set of computational models applicable to the terminal velocity and drag coefficient of oil droplets in the range of 20 < Re < 1200 in a non-pure system are obtained by organizing the experimental data and comparing with the traditional correlation equation, respectively. The models involve dimensionless parameters such as Eo, Mo, and We numbers with fitting coefficients up to 0.984.

Multicomponent Photocatalytic-Dispersant System for Oil Spill Remediation.

In the present work, the potential application of a fabricated halloysite nanotubes-Ag-TiO2 (HNT-Ag-TiO2) composite loaded with a binary surfactant mixture made up of lecithin and Tween 80 (LT80) in remediating oil spillages was examined. The as-prepared Ag-TiO2 that was used in the fabrication of the HNT-Ag-TiO2-LT80 composite was characterized by X-ray diffraction, Raman spectroscopy, UV-vis and diffuse reflectance spectroscopy, CV analyses, and SEM-EDX. The synthesized composite was also characterized by thermogravimetric analysis, Fourier-transform infrared spectroscopy, and scanning electron microscopy-energy dispersive X-ray spectroscopy. The synthesized composite was active in both the UV and visible light regions of the electromagnetic spectrum. The oil-remediating potential of the as-prepared composite was examined on crude oil, and aromatics and asphaltene fractions of crude oil. The composite was able to reduce the surface tension, form stable emulsions and smaller oil droplet sizes, and achieve a high dispersion effectiveness of 91.5%. A mixture of each of the crude oil and its fractions and HNT-Ag-TiO2-LT80 was subjected to photodegradation under UV light irradiation. The results from the GC-MS and UV-vis analysis of the photodegraded crude oil revealed that the photocatal composite was able to photodegrade the crude oil, aromatics, and asphaltene fractions of crude oil with the formation of intermediate photodegradation products depicting that the HNT-Ag-TiO2-LT80 has a potential as an oil spill remediation material.

Plant-Based Oil-in-Water Food Emulsions: Exploring the Influence of Different Formulations on Their Physicochemical Properties.

The global focus on incorporating natural ingredients into the diet for health improvement encompasses ω-3 polyunsaturated fatty acids (PUFAs) derived from plant sources, such as flaxseed oil. ω-3 PUFAs are susceptible to oxidation, but oil-in-water (O/W) emulsions can serve to protect PUFAs from this phenomenon. This study aimed to create O/W emulsions using flaxseed oil and either soy lecithin or Quillaja saponins, thickened with modified starch, while assessing their physical properties (oil droplet size, ζ-potential, and rheology) and physical stability. Emulsions with different oil concentrations (25% and 30% w/w) and oil-to-surfactant ratio (5:1 and 10:1) were fabricated using high-pressure homogenization (800 bar, five cycles). Moreover, emulsions were thickened with modified starch and their rheological properties were measured. The physical stability of all emulsions was assessed over a 7-day storage period using the TSI (Turbiscan Stability Index). Saponin-stabilized emulsions exhibited smaller droplet diameters (0.11-0.19 µm) compared to lecithin (0.40-1.30 µm), and an increase in surfactant concentration led to a reduction in droplet diameter. Both surfactants generated droplets with a high negative charge (-63 to -72 mV), but lecithin-stabilized emulsions showed greater negative charge, resulting in more intense electrostatic repulsion. Saponin-stabilized emulsions showed higher apparent viscosity (3.9-11.6 mPa·s) when compared to lecithin-stabilized ones (1.19-4.36 mPa·s). The addition of starch significantly increased the apparent viscosity of saponin-stabilized emulsions, rising from 11.6 mPa s to 2117 mPa s. Emulsions stabilized by saponin exhibited higher stability than those stabilized by lecithin. This study confirms that plant-based ingredients, particularly saponins and lecithin, effectively produce stable O/W emulsions with flaxseed oil, offering opportunities for creating natural ingredient-based food emulsions.

Physical properties and in-vitro gastrointestinal digestion of oil-in-water emulsions stabilized by single- and dual-modified cassava starches with cross-linking and octenylsuccinylation

The different modified cassava starches (MCS) obtained by either single or dual modifications with cross-linking (CL) and octenylsuccinylation (OS), including 2%CL, 3%OS, 2%CL-3%OS, and 3%OS-2%CL, were used to stabilize soybean oil-in-water emulsions (oil content 10% (w/w)) at a concentration of 4.5% (w/w) compared to native cassava starch (NCS) and their physical properties and in-vitro gastrointestinal digestion were investigated. The emulsions stabilized with NCS and 2%CL-MCS had larger oil droplet sizes, higher viscosity, and lower negative charge than the emulsions stabilized by single- or dual-MCS with 3%OS. All MCS-stabilized emulsions showed a higher emulsion stability against creaming than the NCS-stabilized emulsion. Under a simulated gastrointestinal tract, all 3%OS-MCS promoted droplet flocculation, while the less ionic NCS and the 2%CL-MCS showed a decrease in droplet size after passing through the mouth and stomach stages. The lipid digestion rate of emulsions stabilized with different MCS and NCS followed the following order: 3%OS >2%CL-3%OS > 3%OS-2%CL > 2%CL > NCS. The NCS- and 2%CL-stabilized emulsions had a lower lipid digestion rate, possibly due to the larger droplet sizes and higher viscosity of the initial emulsions, which delays access of lipase enzymes to lipid droplet surfaces, compared to all 3%OS-MCS-stabilized emulsions.

Development and characterization of novel ultra-stable high internal phase Pickering emulsions gel: Interface structure, stabilization mechanism, and applications

While both protein-polysaccharide complexes and continuous phase gelation showed great potential for stabilizing high internal phase Pickering emulsions (HIPPEs), it is not known which strategies are more effective and adaptive. In this work, HIPPEs gel was prepared by Ca2+-induced continuous phase gelation of ovalbumin (OVA)-low methoxyl pectin (LMP) electrostatic complexes particles (OLECP)-stabilized HIPPEs. The microstructure, rheological properties, stability, and application of HIPPEs and HIPPEs gel were systematically investigated and compared at different LMP concentrations. The results showed that, compared to HIPPEs, continuous phase gelation effectively improved the viscoelasticity, water binding capacity, and hardness of HIPPEs gel due to its robust and developed interface architecture. CLSM and cryo-SEM observations revealed that OLECP interconnected with each other in the continuous phase to form an advanced network architecture in HIPPEs. Whereas, a firm gel network structure and a thick interfacial layer were found in HIPPEs gel. More importantly, with increasing pectin concentration, the cross-linking phenomenon of OLECP mainly at the interface, transformed into the gelation behavior of excess pectin molecules dominating in the continuous phase. LMP contributed to the formation of a finer 3D gel network structure and a firmer interfacial layer, providing a smaller oil droplet size and superior stability for HIPPEs gel. The photochemical stability of curcumin was increased from 16.1 ± 1.5 % to 93.7 ± 2.2 % after encapsulation in HIPPEs gel. In vitro digestion results testified that HIPPEs gel (10:15, w/w) can promote fat hydrolysis (from 32.35 ± 3.06 % to 45.52 ± 2.75 %) and enhance the bioaccessibility of curcumin (from 20.1 ± 1.5 % to 32.8 ± 2.6 %) compared to bulk oil. Besides, compared with HIPPEs, HIPPEs gel showed poor printability because of improper printing adaptability and liquidity. In a nutshell, our work provides valuable information for developing novel HIPPEs gels for various food applications.

Encapsulation of tuna oil by liquid and solid self‐emulsifying delivery system: in vitro digestion and oxidative stability assessment

SummaryTuna oil, one of the main sources of omega‐3 polyunsaturated fatty acids (omega‐3 or n‐3 PUFAs), is known to have limited bioavailability due to its hydrophobicity. Moreover, the main n‐3 PUFAs found in tuna oil, that is docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are prone to oxidation. To overcome these drawbacks, tuna oil encapsulation via liquid (LSEDS) and solid self‐emulsifying delivery system (SSEDS) was developed. Different LSEDS formulations were prepared and evaluated in terms of tuna oil droplet size and dispersibility. Accordingly, the formulation with small droplets size and narrow size distribution was selected and further developed into SSEDS by spray drying process. SSEDS was thereafter characterised concerning production yield, moisture content, size, size distribution and morphology. Furthermore, the in vitro simulated gastrointestinal model of LSEDS and SSEDS was carried out. The results showed that after intestinal digestion stage, 87% and 72% of DHA were released from LSEDS and SSEDS, respectively. Therefore, these formulations of LSEDS and SSEDS were proven their ability to enhance the bioaccessibility of DHA. Moreover, the oxidative stability of LSEDS and SSEDS formulation was investigated and compared to pure tuna oil using non‐isothermal differential scanning calorimetry (DSC) analysis under oxygen. The results showed that both LSEDS and SSEDS formulations exhibited a high oxidative resistance with a higher energy needed to induce tuna oil oxidation than pure tuna oil. The chemical and thermal stability given by LSEDS and SSEDS may be efficiently applied in food area to enhance the techno‐functional properties of hydrophobic compounds.

Fabrication and characterization of W1/O/W2 double emulsions stabilized with Pleurotus geesteranus protein particles via one-step emulsification

In this study, Pleurotus geesteranus protein isolate (PPI) with low solubility in water was fabricated into nanoparticle (PPIP) that can be uniformly dispersed in pH 7.0 aqueous solution using pH cycle method. PPIP with a zeta potential of −19.21 mV had a mean size of 250.53 nm and two main peaks in particle size distribution profile. This was consistent with the TEM results, which existed both as individual particles and as particle aggregates. The main force responsible for maintaining the structure of protein particles was hydrogen bonding. Interestingly, these protein particles were successfully utilized to fabricate W1/O/W2 double emulsions using one-step homogenous emulsification, and the formation and properties of PPIP-stabilized W1/O/W2 double emulsions were significantly influenced by the protein particle concentration, oil content, and salt concentration in W2 continuous phase. Specifically, higher particle concentration and salt concentration caused a reduction in the number of W1/O droplets and the size of oil droplets. Conversely, an increase in oil content increased the number of W1/O droplets primarily due to the augmentation in the size of oil droplets. The gel strength of double emulsions was enhanced with particle concentration and oil content, as this led to the formation of stronger particle networks and droplet networks. While an opposite phenomenon was found in increasing salt concentration in W2 continuous phase, possibly resulting from the disruption of the ordered gel network. These findings not only provide new food-grade emulsifiers for W1/O/W2 double emulsions, but also broaden the application of edible mushroom proteins in food industry.

Bioactive foamulsion gels: a unique structure prepared with gellan gum and Acanthophyllum glandulosum extract.

Foamulsions have become increasingly popular in the food industry due to their ability to enhance the textural, sensory and health-promoting properties of food products. This study was therefore aimed to design and prepare a novel gelled structure, foamulsion gel containing 0-600 g L-1 oil, with gellan gum (GG; 7, 10 and 13 g L-1) and saponin-rich antioxidant Acanthophyllum glandulosum extract (AGE; 2, 6 and 10 g L-1). The interaction between components was confirmed by infrared spectroscopy. The overrun and porosity of the foamulsion gels increased with antioxidant AGE (1.30 times) and reduced with oil (up to ca 70% and 30%, respectively) and GG levels. The systems were highly stable, and no water or oil was released during the physical stability experiments. Microscopic images showed that the size of air cells was significantly larger than that of oil droplets. The foamulsion gels based on 13 g L-1 GG and 10 g L-1 AGE had markedly higher elastic (G') and viscous (G'') moduli than other samples, and exhibited an elastic and solid-like behavior (G' > G''). The highest gel firmness was found in oil-free sample, and the presence of oil resulted in a lower firmness induced by the larger size and lubrication effect of oil droplets. As a result, the interactions between AGE, GG and oil could lead to the creation of new aerated structures known as bioactive foamulsion gels. These gels exhibit excellent foamability, stability and viscoelasticity and may find applications in the development of novel, healthy and low-calorie aerated foods. © 2024 Society of Chemical Industry.

Impact of the drying rate on product properties of spray dried emulsions to enable a targeted product design

Spray drying of emulsions is a widespread encapsulation technique to produce a large variety of powdered formulations. The oil droplet size (ODS) in the powder is critical for product quality, influencing key product parameters such as the encapsulation efficiency (EE) of the oil. To expand the understanding of changes in ODS and structure formation during the drying step. For this purpose, model oil-in-water emulsions were spray-dried at varying air inlet and outlet temperatures. The powders were characterized regarding ODS and EE. Smaller ODS were observed for parameter combinations where higher drying rates are expected due to decreased coalescence. The results for the EE revealed no clear trend. An increase of air outlet temperature first led to a small decrease in EE followed by a distinct increase of EE. The first decrease may indicate a collapse of the particle morphology but more detailed investigations are necessary to explore these phenomena.

Pretreatment of alkali/surfactant/polymer (ASP)-flooding produced wastewater by electron beam radiation to improve oil-water separation

The management of wastewater produced from alkali/surfactant/polymer (ASP) flooding, known for its considerable volume and high emulsion stability, poses a challenge in oilfields globally. This study has demonstrated that ionizing irradiation is a promising pretreatment method for ASP wastewater to improve oil-water separation. After a settling time of 1 h, approximately 69.5% of oil remained in the raw ASP wastewater, while only 20–29% of the oil persisted in the liquid phase following radiation at absorbed doses ranging from 0.1 to 5.0 kGy. A noticeable increase in the size of oil droplets and reduction in turbidity was observed after irradiation. Further analysis revealed that the combination of surfactant, sodium dodecyl sulfate (SDS) and alkali exhibits a synergistic impact, leading to a substantial reduction in interface tension of ASP wastewater. Notably, ionizing irradiation induces several key changes that are crucial for efficient demulsification. The transformation of the wastewater's rheological behavior from pseudoplastics to a Newtonian fluid accompanied by a reduction in viscosity, the increased interfacial tension at both liquid-air and liquid-oil interfaces, along with the degradation of organic components such as partly hydrolyzed polyacrylamide (HPAM) and SDS, all contribute to the coalescence and floatation of oil droplets.

Intensification of multiphase systems with a jet‐loop reactor: characterization of mass transfer, mixing time, drop oil size, and biomass growth

AbstractBACKGROUNDThe development of processes for transforming vegetable oils into useful products has received increasing attention in the biotechnological field. The reactor used for this purpose should meet adequate mass transfer, mixing, and oil dispersion conditions. In this work, comprehensive research into the use of a jet‐loop reactor as a potential alternative to airlift and stirred tank reactors was conducted in the presence of avocado oil in a water‐air system. Additionally, the assessment of the jet‐loop for biomass growth in the presence of oil was performed.RESULTSThe increase of avocado oil from 1% to 5% v/v resulted in a reduction in the performance of the three reactors. Despite the airlift reactor having the lowest power input, it exhibited the worst performance in terms of mass transfer, mixing, and oil dispersion. The estimation of the energetic oxygen transfer efficiency (Kg O2 KW−1 h−1) allowed the determination that the jet‐loop reactor was superior to the stirred tank. This superiority was attributed to the low values of the mixing time and oil droplet diameter observed in the jet‐loop reactor. Finally, all these parameters had a positive impact on the growth of Wautersia eutropha in the jet‐loop reactor compared with the other two reactors.CONCLUSIONThe results showed that the jet‐loop reactor presented superior performance in most cases compared to the stirred tank and airlift reactors. Particularly, the jet‐loop exhibits an interesting potential to reduce the size of the avocado oil droplets, which could lead to a significative increase in the growth rate of Wautersia eutropha. © 2023 Society of Chemical Industry (SCI).

Effect of different forms of nanocellulose on the stability of pork myofibrillar proteins' emulsion system

SummaryMyofibrillar proteins (MP) and two forms of nanocellulose (cellulose nanofibers [CNFs] and cellulose nanocrystals [CNCs]) were used to prepare oil‐in‐water emulsion. The effect of CNFs and CNCs on the properties of pork MP‐lard emulsion was studied by analysing the emulsion index, microstructure, oil droplet size, zeta potential and rheological behaviour of emulsion. The results showed that both CNFs and CNCs improved MP‐lard emulsion stability. At the same nanofiber concentration, the creaming index of CNFs stabilised emulsion was lower than that of CNCs stabilised emulsion, especially at the concentration of 0.5%, emulsion prepared with CNFs has no phenomenon of creaming index, while emulsion prepared with CNCs still has creaming index phenomenon. At the same nanofiber concentration, the oil droplet distribution of CNFs stabilised emulsion was more uniform, especially at low concentrations (≤0.5%). At higher cellulose concentration (≥0.75%), the particle size of CNFs stabilised emulsion was larger than that of CNCs stabilised emulsion. CNFs stabilised emulsion had a higher zeta potential and modulus than that of CNCs stabilised emulsion and the emulsion formed by CNFs was more viscoelastic.

Foam and emulsion properties of crude saponin extract from saffron (Crocus sativus L.) corm

The emulsion and foam stability of the crude saponin extract from the saffron corm (SS) were compared with commercially available saponin (CS) and Tween 60 (T60). The purity of the SS sample was calculated relative to CS and showed a value of 84.43%. Most stable emulsions with the smallest oil droplet size were acquired with T60. Also, T60 showed the lowest surface tension, interfacial tension, and the lowest contact angle. However, a reduction of interfacial tension and surface tension up to 77% and 32% was recorded for SS, respectively. Commercially available saponin indicated the best foam stability regarding film drainage, coalescence, and bubble disproportionation due to its highest solution viscosity. The antioxidant activity of samples was evaluated regarding the FRAP assay and the DPPH free radical scavenging activity. The results showed FRAP values of 2.41 and 1.20 mmol L−1 Fe (II)/100 g sample, and DPPH IC50 values of 2103 and 2326 mg kg−1 for CS and SS, respectively. The investigation showed that SS can form stable emulsions and abundant and persistent foams. Our results provide valuable insights for using saffron corm saponin extract as a new potential natural surfactant for selected applications of the food and pharmaceutical industries.

Crankcase Explosions in Marine Diesel Engines: A Computational Study of Unvented and Vented Explosions of Lubricating Oil Mist

Accidental crankcase explosions in marine diesel engines are presumably caused by the inflammation of lubricating oil in air followed by flame propagation and pressure buildup. This manuscript deals with the numerical simulation of internal unvented and vented crankcase explosions of lubricating oil mist using the 3D CFD approach for two-phase turbulent reactive flow with finite-rate turbulent/molecular mixing and chemistry. The lubricating oil mist was treated as either monodispersed with a droplet size of 60 μm or polydispersed with a trimodal droplet size distribution (10 μm (10 wt%), 250 μm (10 wt%), and 500 μm (80 wt%)). The mist was partly pre-evaporated with pre-evaporation degrees of 60%, 70%, and 80%. As an example, a typical low-speed two-stroke six-cylinder marine diesel engine was considered. Four possible accidental ignition sites were considered in different linked segments of the crankcase, namely the leakage of hot blow-by gases through the faulty stuffing box, a hot spot on the crankpin bearing, electrostatic discharge in the open space at the A-frame, and a hot spot on the main bearing. Calculations show that the most important parameter affecting the dynamics of crankcase explosion is the pre-evaporation degree of the oil mist, whereas the oil droplet size distribution plays a minor role. The most severe unvented explosion was caused by the hot spot ignition of the oil mist on the main bearing and flame breaking through the windows connecting the crankcase segments. The predicted maximum rate of pressure rise in the crankcase attained 0.6–0.7 bar/s, whereas the apparent turbulent burning velocity attained 7–8 m/s. The rate of heat release attained a value of 13 MW. Explosion venting caused the rate of pressure rise to decrease and become negative. However, vent opening does not lead to an immediate pressure drop in the crankcase: the pressure keeps growing for a certain time and attains a maximum value that can be a factor of 2 higher than the vent opening pressure.