Physical and oxidative stability of high fat fish oil-in-water emulsions stabilized with sodium caseinate and phosphatidylcholine as emulsifiers

Interfacial effects of gallate alkyl esters on physical and oxidative stability of high fat fish oil-in-water emulsions stabilized with sodium caseinate and OSA-modified starch

Effects of sodium caseinate (SC) and its combination with OSA-modified starch (SC-OS; 1:1) alone and with n-alkyl gallates (C0-C18) on the physical and oxidative stability of high-fat fish oil-in-water emulsion were evaluated. SC emulsion contained the smallest droplets and highest viscosity due to the fast adsorption at droplet surfaces. Both emulsions had non-Newtonian and shear-thinning behavior. A lower accumulation of lipid hydroperoxides and volatile compounds was found in SC emulsion due to its better Fe²⁺ chelating activity. The incorporated short-chain gallates (G1 > G0 ∼ G3) in SC emulsion had a strong synergistic effect against lipid oxidation compared to that of SC-OS emulsion. The better antioxidant efficiency of G1 can be related to its higher partition at the oil-water interface, while G0 and G3 had a higher partition into the aqueous phase. In contrast, G8, G12, and G16 added emulsions indicated higher lipid oxidation due to their internalization inside the oil droplets.

Understanding of the key factors influencing the properties of emulsions stabilized by sodium caseinate

Emulsions can be easily destabilized under various conditions during preparation and storage. Therefore, it is necessary to understand the factors that influence the stability of emulsions, which is essential for their subsequent studies. Sodium caseinate (CAS) is a well-used nutritional and functional ingredient in emulsion preparation due to its good solubility and emulsifying properties. CAS-stabilized emulsions can be considered good food emulsion delivery systems, but their applications are still limited under certain conditions due to their instability to creaming and aggregation. Therefore, the purpose of this review is to provide a complete overview of how different environmental stresses and processing conditions affect the stability of CAS-stabilized emulsions and how to improve their stability. Initially, the general properties of CAS as emulsifiers and the characterization of CAS-stabilized oil-in-water (O/W) emulsions were summarized. Second, the major instability mechanisms that operate in CAS-stabilized emulsions were presented. Furthermore, the general factors such as pH, emulsifier concentration, ionic strength, oxidation, and processing conditions, affecting the stability of CAS-stabilized O/W emulsion, were discussed. On this basis, the commonly used methods for evaluating emulsion stability are introduced. Finally, state-of-the-art strategies to improve CAS-based emulsion stability are also described and summarized. This review is expected to provide a theoretical basis for the future applications of CAS in food emulsions.

Recent progress in fish oil-based emulsions by various food-grade stabilizers: Fabrication strategy, interfacial stability mechanism and potential application

Fish oil, rich in a variety of long-chain ω-3 PUFAs, is widely used in fortified foods due to its broad-spectrum health benefits. However, its undesired characteristics include oxidation sensitivity, poor water solubility, and fishy off-flavor greatly hinder its exploitation in food field. Over the past two decades, constructing fish oil emulsions to encapsulate ω-3 PUFAs for improving their physicochemical and functional properties has undergone great progress. This review mainly focuses on understanding the fabrication strategies, stabilization mechanism, and potential applications of fish oil emulsions, including fish oil microemulsions, nanoemulsions, double emulsions, Pickering emulsions and emulsion gels. Furthermore, the role of oil-water interfacial stabilizers in the fish oil emulsions stability will be discussed with a highlight on food-grade single emulsifiers and natural complex systems for achieving this purpose. Additionally, its roles and applications in food industry and nutrition field are delineated. Finally, possible innovative food trends and applications are highlighted, such as novel fish oil-based delivery systems construction (e.g., Janus emulsions and nutraceutical co-delivery systems), exploring digestion and absorption mechanisms and enhancing functional evaluation (e.g., nutritional supplement enhancer, and novel fortified/functional foods). This review provides a reference for the application of fish oil-based emulsion systems in future precision diet intervention implementations.

Systematic comparison of structural and lipid oxidation in oil-in-water and water-in-oil biphasic emulgels: effect of emulsion type, oil-phase composition, and oil fraction

BACKGROUND

Because many common foods are emulsions (mayonnaise, margarine, salad dressing, etc.), a better understanding of lipid oxidation is crucial for the formulation, production, and storage of the relevant consumer products. We prepared oil-in-water (O/W) and water-in-oil (W/O) emulgels, and their architecture was characterized before monitoring lipid oxidation under thermally accelerated conditions to systematically compare the effect of emulsion type, oil composition, and oil fraction on the structure and lipid oxidation in thee biphasic emulgel systems.

RESULTS

Higher susceptibility of lipids to oxidation (>2.5 times) was observed in the biphasic O/W and W/O emulgels than in soybean oil owing to an interfacial region. In the heterogeneous emulsion systems, W/O emulgels had oxidation resistance than O/W emulgels did. Compared with the oil-phase composition of high oleic sunflower, soybean, and flaxseed oils, oxidation sensitivity of emulsified lipids was significantly raised as the degree of unsaturation increased from 100.72 to 203.07. Moreover, increasing oil fraction from 75% to 85% led to an obvious increase in total oxidation in O/W emulgels but a decrease in W/O emulgels. In addition to emulsion size and oil unsaturation, viscoelasticity had a remarkable effect on the low-unsaturated oil oxidation (e.g. high oleic sunflower oil).

CONCLUSION

Physical and structural phenomena played important roles in lipid oxidation based on a mass transport principle. These findings provide novel information for designing the structures of emulsion gels for controlling lipid oxidation through the cooperation of both formulation and architecture principles. © 2022 Society of Chemical Industry.

Effect of biopolymers concentration and drying methods on physicochemical properties of emulsion-templated oleogel

In current study, oleogel containing surface-active (sodium caseinate) and non-surface active biopolymers (xanthan gum) prepared in different concentrations through emulsion template (containing 60% canola oil) and dried by freeze-drying. Results showed that biopolymer content affects the oleogel structure: applying the biopolymer combination with increased concentration mainly sodium caseinate, resulted in lower droplet size in emulsions and obtained oleogels with higher firmness and less oil loss. Therefore, samples containing 4% sodium caseinate with 0.2% and 0.4% xanthan were selected as the superior formulas for examining deeply the drying methods' effects (freeze and vacuum-oven drying) on oleogel's physicochemical properties such as hardness, rheology, XRD, color, and oxidative stability. Freeze-drying with higher content of xanthan (0.4% w/w) generated a high mechanical strength oleogel. However, reducing xanthan concentration (0.2% w/w) reduced the gel strength, probably due to not enough viscoelasticity in oil droplets interface. Nevertheless, the charm of freeze-drying method is high-quality dried products in optimized biopolymer concentration due to the water removal by sublimation of ice crystals. Contrariwise, vacuum-oven revealed soft-discolored materials even in high biopolymers concentrations due to the higher temperature and structural collapse. Independence of biopolymer concentration and drying method, no significant difference in XRD patterns, and oxidative stability was observed.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-021-05214-1.

The relationship between the structure and functionality of essential PUFA delivery systems based on sodium caseinate with phosphatidylcholine liposomes without and with a plant antioxidant: an in vitro and in vivo study

The aim of this work was to establish the main relationship between the structure and functionality of supramolecular complexes formed by sodium caseinate (SC) with phosphatidylcholine (PC) liposomes filled with fish oil (FO) to an equal mass ratio of n-3 to n-6 polyunsaturated fatty acids (PUFA) in the absence and presence of one of the most effective plant antioxidants, namely the essential oil of clove buds (EOC). The functionality of the supramolecular complexes (SC-PC-FO and SC-PC-FO-EOC) was considered from the point of view of the possibility of their use as effective delivery systems for long-chain n-3 PUFAs (eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids from FO). The laser light scattering method was used in the static, dynamic and electrophoretic modes to characterize the structure and thermodynamic parameters of the supramolecular complexes in an aqueous medium. It was found that the SC-PC-FO and SC-PC-FO-EOC complex particles had the following similar properties: nanosize; a spherical shape; 100% solubility in an aqueous medium (pH 7.0, ionic strength = 0.001 M); a high encapsulating ability of SC (up to 70%) in relation to the studied liposomes; and a high protective ability relative to lipid autooxidation (up to 96% on the 20th day of storage at room temperature in light). In addition, a sequential transformation of both the structural and thermodynamic parameters has been observed for the complex particles under in vitro simulated gastrointestinal (GI) conditions in accordance with the INFOGEST protocol. A greater release of the encapsulated lipids from the enzymatically hydrolyzed complex particles was observed at the small intestine stage compared to their release at the gastric stage. These data were in good agreement with those on the assessment of the bioavailability of the target PUFAs in in vivo experiments based on the chronic intake of aqueous solutions of the complexes (both SC-PC-FO and SC-PC-FO-EOC) by experimental mice for 92 days. Liver lipid profiles of the mice, obtained by gas-liquid chromatography, showed the following: (i) an almost twofold increase in the DHA content as compared with that of the control; (ii) an almost threefold decrease in the mass ratio of arachidonic acid (AA) (C20:4 n-6) to DHA (C22:6 n-3) compared to that of the control due to both a significant decrease in the AA content and a simultaneous pronounced increase in the DHA content; and (iii) an almost twofold decrease in the mass ratio of the total amounts of n-6 to n-3 PUFAs compared to that of the control.

Small-Angle Neutron Scattering Study of High Fat Fish Oil-In-Water Emulsion Stabilized with Sodium Caseinate and Phosphatidylcholine

We report on small-angle neutron scattering (SANS) investigations of separate phase domains in high fat (70%) oil-in-water emulsions emulsified with the combination of sodium caseinate (CAS) and phosphatidylcholine (PC). The emulsion as a whole was studied by contrast variation to identify scattering components dominated by individual emulsifiers. The emulsion was subsequently separated into the aqueous phase and the oil-rich droplet phase, which were characterized separately. Emulsions produced with 1.05% (w/w) CAS and PC fraction which varies between 1.75% (w/w) and 0.35% (w/w) provided droplets between 10 and 19 μm in surface weighted mean in 70% fish oil-in-water emulsions. At least two-third of the overall CAS is associated with the interface, while the rest remains with the aqueous phase. Six percent of PC formed a monolayer in the interface, while the rest of the PC remains in the droplet phase in the form of multilayers. When the separated components were resuspended, the resuspended emulsion showed similar characteristics compared to the original emulsion in terms of droplet size distribution and neutron scattering. Instead, CAS in the aqueous phase separated from the emulsion shows aggregation not present in the corresponding CAS-in-D₂O system.

The composition and oxidative stability of vegetarian omega-3 algal oil nanoemulsions suitable for functional food enrichment

BACKGROUND

Long chain omega-3 polyunsaturated fatty acid (LCn3PUFA) nanoemulsion enriched foods offer the potential to address habitually low oily fish intakes. Nanoemulsions increase LCn3PUFA bioavailability, although they may cause lipid oxidation. The present study examined the oxidative stability of LCn3PUFA algal oil-in-water nanoemulsions created by ultrasound using natural and synthetic emulsifiers during 5 weeks of storage at 4, 20 and 40 °C. Fatty acid composition, droplet size ranges and volatile compounds were analysed.

RESULTS

No significant differences were found for fatty acid composition at various temperatures and storage times. Lecithin nanoemulsions had significantly larger droplet size ranges at baseline and during storage, regardless of temperatures. Although combined Tween 40 and lecithin nanoemulsions had low initial droplet size ranges, there were significant increases at 40 °C after 5 weeks of storage. Gas chromatograms identified hexanal and propanal as predominant volatile compounds, along with 2-ethylfuran, propan-3-ol and valeraldehyde. The Tween 40 only nanoemulsion sample showed the formation of lower concentrations of volatiles compared to lecithin samples. The formation of hexanal and propanal remained stable at lower temperatures, although higher concentrations were found in nanoemulsions than in bulk oil. The lecithin only sample had formation of higher concentrations of volatiles at increased temperatures, despite having significantly larger droplet size ranges than the other samples.

CONCLUSION

Propanal and hexanal were the most prevalent of five volatile compounds detected in bulk oil and lecithin and/or Tween 40 nanoemulsions. Oxidation compounds remained more stable at lower temperatures, indicating suitability for the enrichment of refrigerated foods. Further research aiming to evaluate the oxidation stability of these systems within food matrices is warranted. © 2019 Society of Chemical Industry.

Influence of Ternary Emulsifier Mixtures on Oxidative Stability of Nanoemulsions Based on Avocado Oil

The aim of this work was to study the effect of two emulsifiers (M1: SL-soy lecithin, Tw80-Tween 80 and CasCa-calcium caseinate and M2: SL-soy lecithin, Tw80-Tween 80 and SE-sucrose esters) on the oxidative stability of avocado oil-based nanoemulsions. Oil-in-water nanoemulsions were prepared using 3.6% w/w of two emulsifier mixtures, which were optimized by mixture experimental design in order to minimize particle size (PS) and polydispersity index (PdI). Then, the oxidative stability of nanoemulsions was evaluated through both an induction period and a quantification of hydroperoxides and thiobarbituric acid reactive species (TBARs) under accelerated storage conditions. The simplex-centroid mixture design showed that PS and PdI varied when proportions of different emulsifiers were modified, obtaining an optimized concentration for each mixture of: 85% SL, 10% Tw80 and 5%CasCa (M1) and 85% SL, 7.4% Tw80 and 7.6% SE (M2) that produced nanoemulsions with PS ~116 nm and PdI < 0.2. Nanoemulsions elaborated with M1 and M2 presented similar particle characteristics and physical stability to the control sample with Tw80. However, M1 nanoemulsions were more stable against lipid oxidation, since they showed the highest induction period and lower formation of hydroperoxides and TBARs during storage.

Characterization of gelatin/chitosan ploymer films integrated with docosahexaenoic acids fabricated by different methods

In this study, docosahexaenoic acid powder-enhanced gelatin-chitosan edible films were prepared by casting, electrospinning and coaxial electrospinning, respectively. The color (CR), transparency (UV), light transmission (UV), mechanical strength (TA-XT), thermal stability (DSC), crystalline structures (XRD), molecular interactions (FTIR), and microstructure (SEM) were assessed in the analytical research. The results of the research showed that the electrospinning process and the coaxial electrospinning process produced a smooth surface visible to by the naked eye and a uniform granular network structure in a unique film-forming manner, thereby exhibiting good water solubility and mechanical properties. In contrast, the casted film was smooth, transparent, and mechanically strong but poorly water soluble. It was also found that the addition of docosahexaenoic acid powder affected the optical, physical and mechanical properties of the film to varying degrees.

Effects of Modified DATEMs with Different Alkyl Chain Lengths on Improving Oxidative and Physical Stability of 70% Fish Oil-in-Water Emulsions

The objective of this study was to produce oxidatively and physically stable 70% fish oil-in-water emulsions by combined use of sodium caseinate (CAS), commercial diacetyl tartaric acid esters of mono- and diglycerides (DATEM), and modified DATEM. First, the optimal formula was determined using DATEM and CAS. Subsequently, modified DATEMs (DATEM C12 and DATEM C14) were designed for investigating both the effects of different alkyl chain lengths and caffeic acid conjugation to the emulsifier on physical and oxidative stability of the emulsions. Emulsions produced with modified DATEMs showed better oxidative stability compared with emulsion using commercial DATEM plus an equivalent amount of free caffeic acid, confirming the advantage of having antioxidant covalently attached to the emulsifier. Results indicated that DATEM_C14 replaced more CAS compared with DATEM_C12 from the interface in 70% fish oil-in-water emulsion. Emulsions produced with DATEM_C14 had significantly decreased amounts of primary and secondary oxidation products compared with emulsions using DATEM_C12.