Oxidative Stability Of Emulsions Research Articles

Characterization of modified starch-based complexes-stabilized linolenic acid emulsions and their enhanced oxidative stability in vitro gastrointestinal digestion

A new approach of fabricating α-linolenic acid emulsions with enhanced oxidative stability in vitro digestion was established, using covalent octenyl succinic anhydride starch (OSAS)-soy protein (SP)-epigallocatechin-3-gallate (EGCG) complexes as emulsifiers. The physicochemical characteristics and surface morphology of emulsions were mainly characterized by rheological measurements, laser scanning microscope (CLSM) and cryo-scanning electron microscopy (Cryo-SEM). Results indicated that emulsions had dense interfacial layers and strong network structures. As a result, the stability and antioxidant ability of emulsions were improved significantly. In addition, the oxidative stability of emulsions in vitro gastrointestinal digestion was explored. Results showed that emulsions could maintain better oxidative stability owing to antioxidant activity of covalent OSAS-SP-EGCG complexes under gastrointestinal conditions. In particular, lipid hydroperoxide and malondialdehyde contents of emulsions prepared by 1:4 complexes were lower than 0.35 mmol/L and 20.5 nmol/mL, respectively, approximately half those of emulsions stabilized by OSAS (0.65 mmol/L and 39.5 nmol/mL). It was indicated that covalent OSAS-SP-EGCG complexes could effectively inhibit α-linolenic acid oxidation in emulsions during vitro gastrointestinal digestion. This work will provide a theoretical basis for the development of α-linolenic acid emulsions, which will help to broaden application of α-linolenic acid in food industry.

Simulating the behavior of antioxidant to explore the mechanisms of oxidative stability in Pickering emulsion

This study explores effective strategies for bolstering emulsion oxidative stability via optimized interfacial distribution of varying hydrophobicity antioxidants (gallic acid, propyl gallate, octyl gallate) in zein nanoparticle (ZP) stabilized Pickering emulsions. Experimental and simulation methods revealed that antioxidant (AO) with higher hydrophobicity or loaded into ZP demonstrated stronger hydrogen bonding and van der Waals interactions with ZP. This increased interfacial loading of antioxidants resulted in improved oxidative stability in Pickering emulsions. The flow, distribution and orientation of AO, as revealed by dissipative dynamics simulations, highlighted the role of hydrophobic interactions during initial AO migration, influenced by varied alkyl chain lengths. Subsequent interface rearrangements arose from conservative force interactions between the AO's phenol hydroxyl ends and ZP. These findings inform effective interfacial engineering to optimize antioxidant efficiency, guiding practical applications in emulsion systems for improved oxidative stability.

Combined effects of high-intensity ultrasound treatment and hydrogen peroxide addition on the thermal stabilities of myofibrillar protein emulsions at low ionic strengths

In this study, the effects of high-intensity ultrasound (HIU) treatment combined with hydrogen peroxide (H2O2) addition on the thermal stability of myofibrillar protein (MP)–stabilized emulsions in low-salt conditions were investigated. Results showed that compared to using either HIU or H2O2 treatment alone, HIU treatment combined with H2O2 was most effective in enhancing the physical stability of emulsions. Moreover, the emulsion stabilized by MPs co-treated with HIU and H2O2 exhibited the most uniform distribution, highest absolute zeta potential, and optimal rheological properties upon heating. This combination effect during heating was caused by the inhibition of disulfide bond cross-linking of myosin heads by H2O2 and the dissociation of filamentous myosin structures using the HIU treatment. In addition, the results of oxidative stability analysis indicated that the addition of H2O2 increased the content of oxidation products; however, the overall influence on the oxidative stability of emulsions was not significant. In conclusion, the combination of HIU and H2O2 treatment is a promising approach to suppress heat-induced MP aggregation and improve the thermal stability of corresponding emulsions.

Sodium Caseinate–Tannic acid Antioxidant Complex act as a High Internal Phase Pickering Emulsions Stabilizer

Background: Emulsion-based formulations have gained attention in food and pharmaceutical products due to their unique properties. However, their use in food product formulation faces problems because of phase separation and fat oxidation, which seriously reduces the quality of the product. Therefore, finding ways to increase the physical and oxidative stability of emulsions is valuable. This work aimed to assess of physicochemical properties of sodium caseinate (SC)-tannic acid (TA) complex treated with heating and ultrasonication as well as their efficiency in physical and oxidative stability of high internal phase Pickering emulsion (HIPPEs) as antioxidant colloidal particles. Methods: SC 1% (w/v) was mixed with a different concentration of TA (0.1, 0.3, 0.5, 0.7, 1% w/v) and the pH of solutions was adjusted to 9. The unheated, heat-treated, and ultrasonicated SC-TA complexes were analyzed to elucidate possible interaction using FTIR, fluorescence spectroscopy, and DSC. Finally, HIPPEs were prepared by mixing the prepared samples and soybean oil at a volume ratio of 25:75 v/v respectively. The microstructure of the most stable HIPPEs was assessed using SEM. Results: Based on the FTIR results the covalent bond in heat-treated SC-TA was formed via the Maillard reaction. In addition, the reduction of free amino groups confirms Schiff base formation. All treated SC-TA samples showed a superior ability to stabilize emulsion in comparison with native SC when used as an aqueous phase of HIPPEs. The long-term physical was observed in heat-treated SC-TA HIPPEs for over two months. In PEs stabilized by SC-TA complex nanoparticles, primary and secondary oxidation product levels were significantly lower than in SC alone. Conclusion: The fabricating antioxidant emulsions using heat-treated SC-TA are a good guarantee for the physical and oxidative stability of food formulations due to TA's intrinsic antioxidant properties and the protective role of SC-TA colloidal particles against coalescence.

Concentration effect of epigallocatechin-3-gallate-bovine bone protein conjugates on emulsion stability

To improve the application of bovine bone protein (BBP) in the food industry, epigallocatechin-3-gallate (EGCG) was modified to EGCG-BBP conjugate. The effect of EGCG-BBP concentration on the emulsifying and oxidative stability of emulsion during the storage period was studied. After covalent modification, the molecular weight of EGCG-BBP increased, while lower maximum fluorescence intensity and the content of α-helix and β-sheet were decreased. The droplet particle size and ζ-potential of emulsion significantly decreased with increasing concentration of EGCG-BBP. Overall, the emulsion prepared by 0.6 % EGCG-BBP was the best, which had the lowest size (723.5 nm) and highest negative charge (−34.18 mV), and smallest droplets, indicating the improved physical stability of the emulsion. Additionally, the peroxide value and thiobarbituric acid reactive substances value of the EGGCG-BBP emulsion significantly decreased to after 20 d of storage. Moreover, the EGCG-BBP stabilized emulsions exhibited strong antioxidant capacity in vitro in an EGCG-BBP concentration-dependent manner. Mechanistically, EGCG-BBP improved the physical and oxidant stability of the emulsion by forming a thicker surface film and increasing the surface charge of droplets. This study demonstrated that EGCG-BBP conjugate can improve the emulsion stability, suggesting that BBP can be used in emulsified food.

Improving chitosan properties through ionic and chemical cross‐linking and their impact on emulsified systems

SummaryChitosan (CS) nanoparticles were formed by two different methodologies: ionic (with sodium tripolyphosphate ‐TPP) and chemical (with genipin ‐GN) cross‐linking. CS–TPP and CS–GN nanoparticles showed positive zeta potential (+46.24 and +62.86 mV, respectively) and sizes ranging from 83.70 to 835.91 nm, respectively. Ionic cross‐linking (with TPP) resulted in particles smaller than those formed by chemical cross‐linking (with GN). The in vitro antibacterial activity revealed an efficient inhibitory effect, especially regarding CS–TPP. In situ, antibacterial and antioxidant studies were carried out on O/W emulsions. The mesophilic and psychrotrophic counts, peroxide value and quantification of conjugated dienes and trienes during time revealed that nanoparticles tend to improve the microbiological and oxidative stability of emulsions. These findings underline the direct relationship between the reduction of particle size and the increase in biopolymer functional properties and expand the possibilities of CS application as a natural preservative of emulsified systems.

Destabilization of oil-in-water emulsions: Influences of interfacial assembly of octenyl succinic anhydride starch and chitosan

This study investigated the formation and destabilization of emulsions with different interfacial assemblies of octenyl succinic anhydride starch (OSAS) and chitosan (CS) at critical pH values. All emulsion droplets were connected to each other via bridging of interfacial percolation and observed to form gel network structures during prolonged storage. In addition, partial pH-dependent flocculation occurred during preparation and decreased the degree of coalescence and creaming of emulsions. Compared to bilayer (OSAS-CS and CS-OSAS) emulsions, the complex (OSAS/CS)-stabilized emulsions were more resistant to coalescence, creaming, and lipid oxidation because of their thick interfacial layers (∼2 μm) and tight percolation networks. The layer-by-layer adsorption of OSAS and CS at the interface may lead to reduced homogeneity and stability of the bilayers, making them relatively susceptible to destabilization. Moreover, an appropriate pH (6.0) facilitated the oxidation stability of emulsions by influencing inter-droplet electrostatic interactions. For complex-stabilized emulsions, the lipid hydroperoxide content at pH 6.0 was reduced by approximately 22.85% and 12.26% respectively compared with that at pH 5.5 and pH 6.5. This work may provide promising insights into the rational design of emulsions with desirable stability by combing biopolymers.

Recent Trends in Improving the Oxidative Stability of Oil-Based Food Products by Inhibiting Oxidation at the Interfacial Region

In recent years, new approaches have been developed to limit the oxidation of oil-based food products by inhibiting peroxidation at the interfacial region. This review article describes and discusses these particular approaches. In bulk oils, modifying the polarity of antioxidants by chemical methods (e.g., esterifying antioxidants with fatty alcohol or fatty acids) and combining antioxidants with surfactants with low hydrophilic-lipophilic balance value (e.g., lecithin and polyglycerol polyricinoleate) can be effective strategies for inhibiting peroxidation. Compared to monolayer emulsions, a thick interfacial layer in multilayer emulsions and Pickering emulsions can act as a physical barrier. Meanwhile, high viscosity of the water phase in emulsion gels tends to hinder the diffusion of pro-oxidants into the interfacial region. Furthermore, applying surface-active substances with antioxidant properties (such as proteins, peptides, polysaccharides, and complexes of protein-polysaccharide, protein-polyphenol, protein-saponin, and protein-polysaccharide-polyphenol) that adsorb at the interfacial area is another novel method for enhancing oil-in-water emulsion oxidative stability. Furthermore, localizing antioxidants at the interfacial region through lipophilization of hydrophilic antioxidants, conjugating antioxidants with surfactants, or entrapping antioxidants into Pickering particles can be considered new strategies for reducing the emulsion peroxidation.

Physical and oxidative stability of fish oil-in-water emulsions stabilized with emulsifier peptides derived from seaweed, methanotrophic bacteria and potato proteins

This study investigated the emulsifying and antioxidant activity of 10 peptides derived from seaweed, methanotrophic bacteria, and potatoes, which were identified as emulsifiers using quantitative proteomics and predictive bioinformatics. The factors (e.g., interfacial properties, secondary structure, net charge) behind the dual-functionality of peptides were characterized and related to peptides’ ability to provide physical and oxidative stability in 5 % fish oil-in-water emulsions during 10 days of storage. The secondary structure of some of the peptides changed from highly disordered to more α-helical (GIIPATILEFLEGQLQEVDNNKDAR and GIIPGTILEFLEGQLQK) or β-strand (VGFACSGSAQTYLSFEGDNTGRGEEEVAI, ELQVSARVTLEIEL, KVKINETVEIKGKFHV, RSPQKKESDMMKATKFAVVLMAAGLTVGCA) structures when adsorbed at the oil-water interface in comparison to aqueous solution. The physical stability analyses confirmed that three seaweed peptides (IDSSFDSLPTDVVRVANSSCDAVE, VGFACSGSAQTYLSFEGDNTGRGEEEVAI, and ELQVSARVTLEIEL), one of the methanotrophic bacteria peptides (KVKINETVEIKGKFHV) and two of the potato peptides (GIIPATILEFLEGQLQEVDNNKDAR and GIKGIIPAIILEFLEGQLQEVDNNKDAR) can indeed produce physically stable emulsions. The predicted emulsifier peptide embedded in methanotrophic bacteria protein (KVKINETVEIKGKFHV) outperformed all the samples in its ability to retard lipid oxidation in emulsions. This was evident as this sample had the lowest hydroperoxides formation (peroxide value < 10 meq O2/ kg oil), tocopherols consumption, and volatile compound concentration, especially for t,t-2,4-heptadienal (14 ng/g sample) and 2-ethyl-furan (no formation). Non-enzymatic browning, which may indicate advanced stages of oxidation, occurred in all emulsions except for those stabilized with KVKINETVEIKGKFHV and sodium caseinate. Even though the positively charged peptides yielded better oxidative stability compared to negatively charged ones, there are several other factors (i.e., length, structure, charge, ability to decrease oil-water interfacial tension) affecting the physical and oxidative stability of emulsions. Therefore, it must be kept in mind that it is the collective action of these factors that ultimately define the functionality of peptides. In its entirety, KVKINETVEIKGKFHV proved to be highly effective in its technological functions as an emulsifier and antioxidant.

50/50 oil/water emulsion stabilized by pea protein isolate microgel particles/xanthan gum complexes and co-emulsifiers

Properties of 50/50 oil/water emulsion stabilized by pea protein isolate microgel particles (PPIMP)/xanthan gum (XG) and co-emulsifiers were evaluated. Three surfactants with different charging characteristics (lauric arginate, LAE, cationic surfactant; diacetyl tartaric acid esters of mono- and diglycerides, DATEM, nonionic surfactant; sodium stearyl lactate, SSL, anionic surfactant) were selected to co-stable emulsion systems with PPIMP/XG, respectively. The emulsions stabilized by PPIMP/XG with LAE reached the minimal droplet size (21.5 μm). The increased addition of either DATEM or SSL decrease the droplet size of emulsion (except for the 0.8 wt% SSL). The emulsions showed lower apparent viscosity at higher DATEM concentration, whereas the vice-versa was observed in the prepared emulsions with SSL. Surfactants with different charge properties can affect the antioxidant properties of the emulsions. All the emulsions containing LAE, DATEM, or SSL can inhibit oxidation by adjusting the concentration, which could be confirmed in a study on the retention of resveratrol. This study provides a deeper insight into the emulsions co-stabilized by different emulsifiers and can be applied in edible O/W emulsions in the food industry like egg-free mayonnaise. • Pea protein microgels and xanthan gum can obtain stable 50 wt% O/W emulsion. • 0.02 wt% lauric arginate in emulsion reduced droplet size and increased viscosity. • Non-ionic surfactant fell emulsion's viscosity and G′, anionic one did opposite. • The existence of surfactants could enhance the oxidation stability of emulsions.

OSA improved the stability and applicability of emulsions prepared with enzymatically hydrolyzed pomelo peel insoluble fiber

Insoluble fibers are not commonly used as emulsion stabilizers because of their compact physical structure and strong hydrophilicity. In this study, pomelo insoluble fibers (PISFs) prepared via cellulase hydrolysis and cellulase hydrolysis followed by octenyl succinic anhydride esterification were used as emulsifiers. The fabricated fibers are denoted as MPISF and OMPISFs, respectively. Unlike MPISF, the OMPISFs with different degrees of substitution (i.e., OMPISF(I) and (II)) increased in the ζ-potentials and contact angles but decreased in the oil-water interfacial tensions to different degrees. Furthermore, an 0.5 wt% OMPISF(II) content was required to prepare a stable non-creaming emulsion, whereas the corresponding MPISF and OMPISF(I) contents were 0.75 wt%. The OMPISF(II)-stabilized emulsions did not undergo creaming after three freeze-thaw treatment cycles. Therefore, the properties of the OMPISF(II)-stabilized emulsions were superior to those of the MPISF- and OMPISF(I)-stabilized emulsions. Additionally, the final amount of free fatty acids released by the OMPISF(II)-stabilized emulsion was 13.3% lower than that released by the MPISF-stabilized emulsion during simulated gastrointestinal digestion. During lipid oxidation processes, the amounts of lipid hydroperoxide and thiobarbituric acid reactive substance produced in the OMPISF(II)-stabilized emulsion were 41.3% and 40.0% lower, respectively, than those in the MPISF-stabilized emulsion. OMPISFs improved the emulsion properties by increasing the oil–water interface stability, forming more solid three-dimensional structures, and promoting electrostatic repulsion between emulsion droplets. These findings indicate that pomelo peel dietary fiber is a promising emulsifier with excellent application potential for the preparation of emulsion stabilizers. • Dual modification of OSA and cellulase endowed PISF an excellent emulsibility. • Freeze-thaw, digestion and oxidative stability of emulsions were improved by OSA. • Higher DS provide emulsions with higher stabilization and application properties. • Improved network, interface layer and electrostatic value were the main mechanism. • This study facilitates the development of utilization of pomelo peel as emulsifier.

Impact of carrier oil on interfacial properties, CBD partition and stability of emulsions formulated by whey protein or whey protein-maltodextrin conjugate

Oil phase composition may affect properties of the oil-water interface and the characteristics of fabricated emulsions. This study aims to investigate the impacts of varying oil phase composition of medium-chain triglyceride (MCT) and long-chain triglyceride (LCT) at volume ratios ranging from 0/100 to 100/0 on biomechanical properties of cannabidiol (CBD)-loaded emulsions stabilized by whey protein (WP) or whey protein-maltodextrin (WP-MD) conjugate. Interfacial tension, surface protein load, droplet size and zeta potential of emulsions significantly increased with increased LCT ratio (p < 0.05). Partition analysis indicated that CBD was mainly located in the oil phase, and its presence was enhanced from 90% to 96% by increasing the LCT proportion. Increased LCT ratio was not beneficial for the physical or oxidation stability of emulsions, but it did increase CBD retention during an accelerated 16-day storage test (55 °C). At all oil compositions, WP-MD stabilized emulsions showed higher surface protein load, smaller particle size, narrower size distribution, lower zeta potential, better protection towards CBD, and improved oxidation stability in comparison with those emulsified with WP alone. These results provide insight into the influences of carrier oil on emulsion characteristics and offer guidance for the rational selection of suitable oil phases for emulsion-based delivery systems.

Encapsulation of curcumin within oil-in-water emulsions prepared by premix membrane emulsification: Impact of droplet size and carrier oil on the chemical stability of curcumin

Oil-in-water emulsions containing curcumin with different droplet sizes were produced by premix membrane emulsification with different carrier oils: tributyrin (short chain triglycerides, SCT), medium chain triglycerides (MCT) and corn oil (long chain triglycerides, LCT). The influence of carrier oil type and droplet size on the physical stability, chemical stability of curcumin and lipid oxidation stability of emulsions were investigated. Turbiscan results indicated that the physical stability of emulsions was related to both carrier oils and emulsion droplet sizes. The oil type and droplet size of emulsions stored at 25 °C showed limited effect on the stability of curcumin, but significantly affected the stability of curcumin at 55 °C. Chemical stability of curcumin decreased with the decrease of emulsion droplet sizes. For each droplet size emulsions, the stability of curcumin decreased in the order SCT > MCT > LCT. Moreover, the lipid oxidation in LCT-based emulsions resulted in lower zeta potential of droplets, which was independent of emulsion droplet sizes. The presence of curcumin improved the oxidative stability of emulsions.

Impact of pea protein-inulin conjugates prepared via the Maillard reaction using a combination of ultrasound and pH-shift treatments on physical and oxidative stability of algae oil emulsions

Algal oil is an aquatic plant source of polyunsaturated fatty acids, especially docosahexaenoic acid (DHA), which may exhibit health benefits when consumed in sufficiently high quantities. But its application as a healthy lipid in functional foods is often limited by its tendency to rapidly oxidize and produce rancid off-flavors. In this study, algal oil-in-water emulsions were prepared using pea protein isolate (PPI)-inulin conjugates as emulsifiers. These conjugates were prepared via the Maillard reaction using a combination of ultrasound and pH-shift treatments. The algal oil phase was mixed with lemon oil (0 to 1.2 wt%) prior to homogenization to improve its sensory characteristics. The addition of 0.6 wt% of lemon oil did not significantly affect the formation and physical stability of the emulsions but it did mask the unpleasant odor of algae oil. The conjugate-stabilized emulsions exhibited shear thinning behavior and had a higher viscosity than PPI-stabilized emulsions. They also had a higher surface load and formed thicker interfacial layers. The conjugates, especially the conjugates prepared by the combined treatments, also significantly improved the physical and oxidative stability of the emulsions. These effects were attributed to an increase in the steric repulsion between the oil droplets due to the hydrophilic inulin chains, as well as to an increase in the antioxidant activity of the interfacial layers due to the presence of more antioxidant proteins. Overall, our results show that the quality attributes and shelf life of DHA-fortified algae oil emulsions can be significantly improved using a plant-based protein-inulin conjugate.

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.

Recent Progress on Protein-Polyphenol Complexes: Effect on Stability and Nutrients Delivery of Oil-in-Water Emulsion System.

Oil-in-water emulsions are widely encountered in the food and health product industries. However, the unsaturated fatty acids in emulsions are easily affected by light, oxygen, and heat, which leads to oxidation, bringing forward difficulties in controlling emulsion quality during transportation, storage, and retail. Proteins are commonly used as emulsifiers that can enhance the shelf, thermal and oxidation stability of emulsions. Polyphenols are commonly found in plants and members of the family have been reported to possess antioxidant, anticancer, and antimicrobial activities. Numerous studies have shown that binding of polyphenols to proteins can change the structure and function of the latter. In this paper, the formation of protein–polyphenol complexes (PPCs) is reviewed in relation to the latters' use as emulsifiers, using the (covalent or non-covalent) interactions between the two as a starting point. In addition, the effects polyphenol binding on the structure and function of proteins are discussed. The effects of proteins from different sources interacting with polyphenols on the emulsification, antioxidation, nutrient delivery and digestibility of oil-in-water emulsion are also summarized. In conclusion, the interaction between proteins and polyphenols in emulsions is complicated and still understudied, thereby requiring further investigation. The present review results in a critical appraisal of the relevant state-of-the-art with a focus on complexes' application potential in the food industry, including digestion and bioavailability studies.

Enhancement of oil productivity of Mortierella alpine and investigation into the potential of Pickering oil-in-water emulsions to improve its oxidative stability.

Mortierella alpine is an oleaginous fungi known for its tendency to produce oil and polyunsaturated fatty acid. Initial experiment indicated that magnesium oxide nanoparticles (MgONPs) accelerated glucose consumption and, consequently, oil production. After enhancement of Mortierella alpine CBS 754.68' oil production, the oxidative stability of the oil rich in long‐chain polyunsaturated fatty acids (arachidonic acid) encapsulated by modified chitosan (CS) was assayed. To confirm the modification of CS, Fourier transform infrared spectroscopy (FTIR) spectrum indicated that the connection between CS and capric acid (CA) as well as stearic acid (SA) was well formed, leading to a considerable improvement in nanoparticle formation, measured by the SEM photographs, and physical and oxidative stability of emulsions. The oxidative stability of Mortierella alpine' oil emulsion in a period of 20 days at ambient temperature was monitored. Of all treated media, CS‐SA nanoparticles were of the most oxidative stability. The rheological tests showed that viscosity behaviors were dominated by elastic behaviors in the impregnating emulsion with unmodified CS at the applied frequencies, and the elastic behavior of the emulsion sample prepared with CS‐SA was slightly higher than that of the emulsion prepared with CS‐CA. The results of redispersibility indicated that the powdered emulsion stabilized by CS‐SA had the lowest water absorption.

Effect of Retort Processing on Low Sodium Instant Noodle Seasoning Based on Oil-in-Water Emulsions

Increasing consumption of instant noodles with high sodium content could elevate the risk of cardiovascular disease. Making instant noodle seasoning in the form of an oil-in-water emulsion was expected to improve the perception of salty taste without increasing the use of salt. However, the oil concentration in the emulsion affects the perception. The addition of antioxidant and retort processing was needed to overcome the nature of the emulsion that was quite susceptible to oxidation and microbial contamination. Preliminary research determined the optimum concentration of oil and antioxidant based on physical characteristics, the perception/gustation of saltiness, and emulsion oxidative stability and the results were used for further research. The final part of the research determined the effects of retort processing on emulsion stability, the perception of saltiness, and the degree of microbial contamination. Three different oil concentrations (26, 27, and 28%) and three types of antioxidants (natural vitamin E, ascorbyl palmitate and mixed tocopherol) were applied to the instant noodle seasoning oil-in-water emulsions. The results showed that using 28% oil and mixed tocopherol had the most stability, was more viscous, and had optimum salty taste perception, which significantly extended the shelf-life of the emulsion compared with the others. Retort processing for 21.5 minutes in 123.5 °C was applied to the seasoning emulsion with 28% oil content and mixed tocopherol. Although, the microbial contamination was significantly reduced, neither the stability of emulsion nor the perception of salty taste was significantly changed by the process.

Interfacial activity of phenolic-rich extracts from avocado fruit waste: Influence on the colloidal and oxidative stability of emulsions and nanoemulsions

The effects of phenolic-rich extracts from avocado peels (AP) and seeds (AS) on the colloidal and the lipid oxidative stability of oil-in-water (O/W) emulsions/nanoemulsions were evaluated. For this purpose, the interfacial tension (IFT) of avocado oil droplets in the presence of extracts and surfactants (low methoxyl pectin, LMP; Tween 80, T80), individually or combined, was assessed. Individually, T80 led to the lowest IFT values (4.25 ± 0.02 mN/m), followed by AS and AP extracts (9.27 ± 0.86 mN/m and 12.31 ± 0.10 mN/m, respectively) and LMP (14.88 ± 0.05 mN/m). Regarding particle size, the emulsions containing AP and AS extracts were smaller (1.45 ± 0.10 μm and 1.11 ± 0.03 μm, respectively), and stabler, than blank emulsions (4.05 ± 0.51 μm). Conversely, the extracts, especially AS extract, reduced the stability of nanoemulsions causing a 24-fold particle size increase. Nevertheless, AP and AS extracts reduced the formation of secondary oxidation products in emulsions/nanoemulsions. These findings provide novel insights into the potential use of avocado waste.

Interfacial Concentrations of Hydroxytyrosol Derivatives in Fish Oil-in-Water Emulsions and Nanoemulsions and Its Influence on Their Lipid Oxidation: Droplet Size Effects.

Reports on the effect of droplet size on the oxidative stability of emulsions and nanoemulsions are scarce in the literature and frequently contradictory. Here, we have employed a set of hydroxytyrosol (HT) esters of different hydrophobicity and fish oil-in-water emulsified systems containing droplets of different sizes to evaluate the effect of the droplet size, surfactant, (ΦI) and oil (ΦO) volume fractions on their oxidative stability. To quantitatively unravel the observed findings, we employed a well-established pseudophase kinetic model to determine the distribution and interfacial concentrations of the antioxidants (AOs) in the intact emulsions and nanoemulsions. Results show that there is a direct correlation between antioxidant efficiency and the concentration of the AOs in the interfacial region, which is much higher (20–200 fold) than the stoichiometric one. In both emulsified systems, the highest interfacial concentration and the highest antioxidant efficiency was found for hydroxytyrosol octanoate. Results clearly show that the principal parameter controlling the partitioning of antioxidants is the surfactant volume fraction, ΦI, followed by the O/W ratio; meanwhile, the droplet size has no influence on their interfacial concentrations and, therefore, on their antioxidant efficiency. Moreover, no correlation was seen between droplet size and oxidative stability of both emulsions and nanoemulsions.