Effect of Salt on the Stability of Vegetable Oil-in-Water Emulsions Stabilized by Soybean Protein and Microgel

2021 ◽  
Vol 43 (5) ◽  
pp. 520-520
Author(s):  
Samuel Olalekan Olusanya Samuel Olalekan Olusanya ◽  
Gbenga Joseph Adebayo Gbenga Joseph Adebayo ◽  
Samuel Olutayo Afolabi and Adewumi Oluwasogo Dada Samuel Olutayo Afolabi and Adewumi Oluwasogo Dada

The preparation of vegetable oil-water emulsions stabilized by soybean protein and microgel is described. The soybean protein was obtained from n-hexane-defatted soybean powder using a Soxhlet extractor. Using equal volumes of oil and water, vegetable oil-water emulsions were formed either by handshaking the mixture or homogenizing the mixture using a Lab homogenizer. The emulsion was characterized using a drop test and microscopy observation. The drop test shows that the preferred emulsion is vegetable oil-in-water (o/w). The effect of salt and emulsifier concentration on the stability and emulsion drop size was investigated. Emulsions stabilized by soybean protein without addition of salt breakdown after 3 days of preparation because of decomposition of the protein. For emulsions stabilized by microgel in the absence of salt, phase separation occurred within 1 hour. At a fixed salt concentration, it was found that increasing the emulsifier concentration has a significant effect on the stability and drop size of the emulsions stabilized by both protein and microgel. For emulsions stabilized by soybean protein, the stability of emulsions increased with increasing salt concentration without any significant influence on the drop size. The results obtained from the surface tension measurement revealed that different mechanisms of stabilization exist in emulsions stabilized by the protein and microgel.

2021 ◽  
Vol 58 (4) ◽  
pp. 271-277
Author(s):  
Zihan Wang ◽  
Liangliang Lin ◽  
Hujun Xu

Abstract In the present work, oil-in-water (O/W) emulsion systems were prepared by using the PEG-7 lauric acid glycerides as the emulsifiers and the liquid paraffin as the oil phase. The influence of processing parameters such as emulsification temperature, stirring speed, emulsifier concentration, oil-water volume ratio and polymer addition on the stability of the emulsion systems was investigated. In order to determine the optimal conditions for the preparation of the emulsion systems based on PEG-7 lauric acid glycerides, a laser drop size analyser and a rotational rheometer were used. As the stability of the O/W emulsion systems increased, the average droplet size of the O/W emulsions measured by the laser droplet size analyser became smaller and the viscosity, storage modulus and loss modulus of the O/W emulsions measured by the rotational rheometer became larger. The following optimal conditions were determined in this study: emulsification temperature 80°C, stirring speed 500 r/min, emulsifier concentration 5 wt%, oil-water volume ratio 1:1 and added amount of xanthan gum 0.2 wt%. The droplet morphology of the O/W emulsion prepared under the optimal conditions, which was characterised by a super high magnification microscope, is small. Furthermore, the long-term stability of the emulsion system prepared under the optimal conditions was investigated over a period of time (4 weeks). The O/W emulsion proves to be well stable even after 4 weeks, with a water separation rate of 0%.


2013 ◽  
Vol 319 ◽  
pp. 233-238 ◽  
Author(s):  
De Hai Yu ◽  
Zhao Yun Lin ◽  
You Ming Li

Octadecenylsuccinic anhydride (ODSA) is an internal sizing agent used to hydrophobize paper and paper board in the process of papermaking. Nano-montmorillonite (MMT) particles and n-dodecane were used as the stabilizer to prepare stable ODSA Pickering emulsions. The effects of pH value, particle concentration, hydrolysis resistance and paper sizing performance of the ODSA Pickering emulsions were investigated. It was found that the stability of ODSA emulsions first increased and then decreased as the pH value decreased. More stable oil-in-water (o/w) emulsion can be made using 10 vol.% n-dodecane. Particle concentration was linked to the formation of particle films at oil–water interface, with a required minimum particle concentration of 1.5 wt.%. Paper sizing degree analysis indicated that the ODSA Pickering emulsions show increased hydrolysis resistance and good sizing performance.


2005 ◽  
Vol 23 (9) ◽  
pp. 777-789 ◽  
Author(s):  
Agnieszka Ewa Wiącek ◽  
Emil Chibowski

The properties of a refined vegetable oil (a mixture of rape and sunflower oils) and of n-tetradecane emulsions in the presence of proteins, i.e. α-lactalbumin and β-casein, were investigated. These proteins differ in their surface affinity, size and structure, and were therefore expected to show some differences in adsorption at the oil droplet/water interface. The oil samples (0.5–5.0 ml in 100 ml water) were emulsified mechanically in the presence of 1.0–5.0 mg of the protein. The stability of the emulsions was investigated via the effective diameter and multimodal size distribution of the droplets using the dynamic light-scattering technique. In addition, the zeta potentials of the emulsions were measured and found to be negative and in the range −5 mV to −20 mV in all systems. Multimodal size distribution analysis showed that soon after preparation the emulsions were quite well monodispersed. In general, α-lactalbumin appeared to be a good or even better emulsifier than β-casein for both kinds of emulsion (vegetable oil and n-tetradecane in water). Moreover, it appeared that for stability of these emulsions, the optimal ratio of oil and protein content was very important.


Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 633
Author(s):  
Firdaous Fainassi ◽  
Noamane Taarji ◽  
Fatiha Benkhalti ◽  
Abdellatif Hafidi ◽  
Marcos A. Neves ◽  
...  

The surface-active and emulsifying properties of crude aqueous ethanolic extracts from untreated olive oil cake (OOC) were investigated. OOC extracts contained important concentrations of surface-active components including proteins, saponins and polyphenols (1.2–2.8%, 7.8–9.5% and 0.7–4.5% (w/w), respectively) and reduced the interfacial tension by up to 46% (14.0 ± 0.2 mN m−1) at the oil–water interface. The emulsifying ability of OOC extracts was not correlated, however, with their interfacial activity or surface-active composition. Eighty percent aqueous ethanol extract produced the most stable oil-in-water (O/W) emulsions by high-pressure homogenization. The emulsions had average volume mean droplet diameters of approximately 0.4 µm and negative ζ-potentials of about -45 mV, and were stable for up to 1 month of storage at 5, 25 and 50 °C. They were sensitive, however, to acidic pH conditions (<5) and NaCl addition (≥25 mM), indicating that the main stabilization mechanism is electrostatic due to the presence of surface-active compounds with ionizable groups, such as saponins.


Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2301
Author(s):  
Man Zhang ◽  
Bin Liang ◽  
Hongjun He ◽  
Changjian Ji ◽  
Tingting Cui ◽  
...  

Appropriate pretreatment of proteins and addition of xanthan gum (XG) has the potential to improve the stability of oil-in-water (O/W) emulsions. However, the factors that regulate the enhancement and the mechanism are still not clear, which restricts the realization of improving the emulsion stability by directional design of its structure. Therefore, the effects of whey protein micro-gel particles (WPMPs) and WPMPs-XG complexes on the stability of O/W emulsion were investigated in this article to provide theoretical support. WPMPs with different structures were prepared by pretreatment (controlled high-speed shear treatment of heat-set WPC gels) at pH 3.5–8.5. The impact of initial WPC structure and XG addition on Turbiscan Indexes, mean droplet size and the peroxide values of O/W emulsions was investigated. The results indicate that WPMPs and XG can respectively inhibit droplet coalescence and gravitational separation to improve the physical stability of WPC-stabilized O/W emulsions. The pretreatment significantly enhanced the oxidative stability of WPC-stabilized O/W emulsions. The addition of XG did not necessarily enhance the oxidative stability of O/W emulsions. Whether the oxidative stability of the O/W emulsion with XG is increased or decreased depends on the interface structure of the protein-XG complex. This study has significant implications for the development of novel structures containing lipid phases that are susceptible to oxidation.


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