Food Emulsions Research Articles

Development of a complex antioxidant for stabilization of dressing enriched with omega-3 fatty acids

The solution to the problem of developing a complex antioxidant for the oxidative stabilization of emulsion systems with a high content of ω-3 polyunsaturated fatty acids (PUFAs) is considered. The object of the study is the oxidative stabilization of dressing using a complex antioxidant of plant origin. The ratio of ω-3:ω-6 PUFAs in model samples of the emulsion system was 1:5.46 and 1:2.21. The reasonable range of antioxidant ratios in the complex was substantiated. The ratio of tocopherol extract, garlic and laurel essential oils in the complex antioxidant is 1:1:1, respectively. Over 30 days of storage of the emulsion system model samples stabilized with a complex antioxidant, there is a gradual accumulation of organic acids (from 0.73 % to 0.75 %). The content of primary oxidation products increases for sample No. 2 – from 0.7 to 1.9 mmol ½ O2/kg, for sample No. 3 – from 0.4 to 1.2 mmol ½ O2/kg. The obtained values of physicochemical parameters meet the requirements of regulatory documentation (DSTU 4561). The peculiarity of the obtained results is that the complex antioxidant showed a significant increase in the stability of the emulsion system of high nutritional value, in particular, slowed down the accumulation of organic acids and peroxides. From a practical point of view, the development can effectively stabilize food emulsion systems with a high content of oxidation-labile PUFAs. An applied aspect of the obtained scientific result is the possibility of modeling and developing new formulations of emulsion and individual fat systems with high nutritional value, containing high PUFA concentrations

Double (W1/O/W2) emulsions prepared with natural vegetable oils and varied inner glucose concentration: Microstructure, rheology and stability

The objective was to study the microstructure, rheology and stability of double (W1/O/W2) emulsions prepared with Tween 80 as hydrophilic emulsifier and coconut, palm or sunflower oil. The effects of glucose concentration in inner aqueous phase and crystallization of lipid phase were analyzed. Aggregation of oil globules by partial coalescence was observed in emulsions prepared with coconut or palm oil because of the crystallization of the lipid phase. The increase of glucose concentration increased the amount of inner water by osmotic swelling and produced a higher partial coalescence degree due to a higher collision frequency between oil globules. Consequently, higher elastic and viscous modules were observed at higher glucose concentration. Fat crystals in lipid phase allowed a partial retention of inner water in the absence of glucose, but they also favored the release of inner water due to partial coalescence. Creaming stability was enhanced by the presence of glucose, because of the formation of a three-dimensional network of aggregated oil globules in emulsions with coconut or palm oil, and a higher packing and global density of oil globules in systems with sunflower oil. The obtained results contribute to the understanding of partial coalescence in W1/O/W2 emulsions, including its effects on inner water release and creaming stability. This work could be relevant for the design and stabilization of vegetable, lipid-reduced food emulsions prepared with natural oils.

Yeast cell wall-derived proteins: Identification and characterization as food emulsifiers

Emulsification activity has been identified in the cell wall mannoproteins of Saccharomyces cerevisiae—which is widely utilized in food products—and their applications have been explored. However, apart from Gas proteins, no other emulsifying cell wall proteins have been identified. A comprehensive understanding of the cell wall proteins involved in emulsification is crucial for advancing their applications. Herein, emulsifying proteins easily released from the cell wall, unlike Gas proteins that are covalently attached, were purified and characterized. Consequently, fructose 1,6-bisphosphate aldolase 1 (Fba1), Enolase (Eno) 1, and Eno2 showed emulsifying activity, and Fba1 had the highest activity. These are glycolytic proteins localized in the cytoplasm and cell wall. Because Triose-phosphate dehydrogenase (glyceraldehyde-3-phosphate dehydrogenase) 2 (Tdh2)—another glycolytic protein—is also localized in the cell wall, its emulsifying ability was investigated. Results indicated that Tdh2 also had strong activity and was comparable to the activity of casein, an emulsifier. Moreover, Tdh2 displayed higher emulsifying activity with 14 and 16 carbon hydrocarbons and stabilized emulsions in soybean oil. Tdh2—with a smaller molecular weight and nearly absent sugar chains compared to Gas proteins—holds promise for investigating the relationship between protein structure and emulsification. This study identified new emulsifying proteins localized to the cell wall through mechanisms other than covalent bonding. In addition, these proteins have potential applications as yeast-derived emulsifiers.

Interfacial behaviour of human bile and its substitution for in vitro lipolysis studies

This study examined the interfacial evolution of individual bile salts (BSs) and their blends with phosphatidylcholine (BS/PC) to simulate the complex behaviour of human bile (HB) during lipolysis at the triglyceride/water interface. Using adsorption and desorption cycles, mimicking exposure to small intestinal fluids, we demonstrate that the interfacial behaviour of HB can be replicated using simple mixtures of BSs and PC. Interfacial tension (IFT) measurements after lipolysis and desorption showed no significant differences (P > 0.05) between HB samples and BS/PC mixtures across the total BS concentrations analysed (2.23–7.81 mM). However, individual BSs without PC yielded significantly different IFT results (P < 0.01) compared to HB, highlighting the importance of phospholipids. Dilatation rheology further emphasised the need for accurate phospholipid representation in bile models. Our results suggest that phospholipids in HB and BS/PC systems enhance resistance to desorption, potentially affecting lipolysis. This is important, as current in vitro digestion models often replicate only intestinal BS concentrations to mimic the behaviour HB in the intestinal lumen. Furthermore, the specific composition of BSs in HB appears less critical than the overall BS and phospholipid content, suggesting that the kinetics of triglyceride digestion is influenced by the combined luminal concentrations of these components. These findings have significant implications for understanding the role of bile in digestion and offer insights for designing more accurate in vitro models to study food emulsions and lipid-based delivery systems.

Studies on the complex interactions of different egg yolk proteins and their roles on rheological properties and stability of high internal phase Pickering emulsions

Egg yolks (EY) are widely used in food emulsions due to their high contents of amphiphilic proteins. This study investigated the different characterization and interactions among low-density lipoproteins (LDL), high-density lipoproteins (HDL) and phosvitins (Pv) using fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM). The high internal-phase Pickering emulsions (HIPPEs) prepared by those protein complexes were analyzed on the basis of droplet size, optical microstructure, confocal microscopy images, interfacial protein compositions and rheological behavior. Results showed that LDL had a smaller particle size (56.44 ± 1.27 nm) and a greater ability to reduce interfacial tension, resulting in smaller droplet sizes (7.09 ± 0.25 μm) in LDL-stabilized HIPPEs. In contrast, HDL possessed higher hydrophobicity and a greater number of free sulfhydryl groups. The droplets in HDL-stabilized HIPPEs were larger, more compact, and exhibited lower solid lipid balance values in rheological tests. The competing adsorption of HDL and LDL at the interface influenced the properties of HDL-LDL prepared emulsions. However, an appropriate amount of Pv promoted the formation of an electrical double layer between LDL and HDL, further reducing interfacial tension. LDL-HDL-Pv complex stabilized HIPPEs displayed more gel-like rheological properties and the highest stability during the storage. This study provides insights for the development of EY protein-based emulsification systems in food industry.

Combining heat treatment and conjugation between guarana extract and pea protein isolate to produce O/W emulsions loaded with vitamin D3

Growing interest in plant-based materials for stabilizing food emulsions is driven by the clean-label trend. Conjugating plant proteins with phenolic compounds from plant extracts enhances their techno-functionality and allows their use as stabilizers of emulsion-based systems. This study aimed to (i) combine heat treatment (HT) and conjugation with guarana extract (GE) to improve the emulsifying ability of pea protein isolate (PPI); (ii) encapsulate vitamin D3 (VD) in PPI/GE-stabilized emulsions; (iii) evaluate the potential of these formulations in improving VD retention during storage and in vitro bioaccessibility. The particles showed a size distribution ranging from 0.5 to 10 µm, depending on the processing sequence. Furthermore, HT on PPI dispersions followed by conjugation with GE led to microgels that stabilized emulsions during 30 days of storage at 25 °C. Also, the conjugates significantly improved VD retention, ranging from 74 to 100 %, after 30 days of storage at 25 °C, even in the presence of UV light. VD-loaded emulsions produced by PPI-GE conjugates showed higher bioaccessibility values (>65 %) compared to emulsions produced by PPI alone (∼58 %) and VD-incorporated sunflower oil (37 %). Given the above, the technological modification of PPI through conjugation with GE phenolic compounds and HT efficiently produced O/W emulsions loaded with VD, improving its bioaccessibility and tailoring a system with potential application in plant-based beverage and dessert formulations.

Impact of hydrophobically modified cellulose nanofiber on the stability of Pickering emulsion containing insect protein.

Cellulose nanofiber (CNF) is an ideal Pickering emulsion stabilizer because of its high aspect ratio and flexibility. CNF was hydrophobically modified by dodecenyl succinic anhydride and used to stabilize the simulated food emulsion system containing insect protein. The prepared dodecenyl succinate nanofiber (D-CNFs) was characterized by contact angle and laser particle size analyzer. The stability of the emulsion system under different conditions was characterized by zeta potential and appearance observation. Lastly, in vitro digestion simulation experiments were carried out to investigate whether the addition of D-CNFs had an effect on the digestion and absorption of oil. The modification process for dodecenyl succinic anhydride to CNFs was that the system temperature was 40 °C, the system pH value was 8.5 and the reaction time was 6 h. The water contact angle of the modified CNFs increased to 83.2 ± 0.9°. D-CNFs were introduced into the simulated food emulsion system containing insect protein. The increase in the concentration of D-CNFs in the aqueous phase promoted the stability of the simulated emulsion system. Increasing the ratio of insect protein was not conducive to the stability of the emulsion. The final fat digestibility of the emulsion with D-CNFs was lower than that of the emulsion without D-CNFs. Overall, the analysis and characterization results show the potential of the modified CNF as a food simulant emulsion stabilizer containing insect protein, which can be used for the development of specific functional foods. © 2024 Society of Chemical Industry.

Exploring the emulsifying properties of biopolymers from Ulva lactuca in stabilizing high internal phase emulsions

Seaweed is a promising raw material for food emulsion stabilizers due to its abundance, low cost, and rich content of various natural biological macromolecules. This study explores the potential of using Ulva lactuca (UL) to stabilize emulsions by employing high-pressure homogenization (HPH) to release its interfacial active components. The results demonstrate that UL extract (ULE) with emulsifying activity was gradually extracted as the HPH pressure increased from 100 to 800 MPa. Concentrating the macromolecular components, specifically polysaccharides and proteins, in the ULE via membrane filtration resulted in a concentrated fraction, referred to as ULER, which exhibited enhanced emulsification performance. By optimizing the oil volume fraction (φ) and pH, it was found that high internal phase emulsions (φ = 0.7–0.8) showed superior viscoelasticity and stability at pH 3–7. In terms of stability, it was observed that the emulsions stabilized by ULER maintained their structure over extended periods without significant phase separation. The strong interaction between exogenous Ca2⁺ and ULER increased the apparent viscosity and viscoelasticity of the emulsion. However, the addition of Ca2⁺ did not significantly enhance the stability of the ULER-stabilized emulsions and, in some cases, even led to a decrease in emulsion stability. This effect may be probably due to the specific interactions between the Ca2⁺ ions and the polysaccharides and proteins in the ULER, which can affect the network structure of the emulsion. Overall, this study highlights the potential of HPH treatment in processing UL to transform it into an effective emulsion stabilizer for applications in the food industry.

The emulsifying capacity and stability of potato proteins and peptides: A comprehensive review.

The potato has recently attracted more attention as a promising protein source. Potato proteins are commonly extracted from potato fruit juice, a byproduct of starch production. Potato proteins are characterized by superior techno-functional properties, such as water solubility, gel-forming, emulsifying, and foaming properties. However, commercially isolated potato proteins are often denatured, leading to a loss of these functionalities. Extensive research has explored the influence of different conditions and techniques on the emulsifying capacity and stability of potato proteins. However, there has been no comprehensive review of this topic yet. This paper aims to provide an in-depth overview of current research progress on the emulsifying capacity and stability of potato proteins and peptides, discussing research challenges and future perspectives. This paper discusses genetic diversity in potato proteins and various methods for extracting proteins from potatoes, including thermal and acid precipitation, salt precipitation, organic solvent precipitation, carboxymethyl cellulose complexation, chromatography, and membrane technology. It also covers enzymatic hydrolysis for producing potato-derived peptides and methods for identifying potato protein-derived emulsifying peptides. Furthermore, it reviews the influence of factors, such as physicochemical properties, environmental conditions, and food-processing techniques on the emulsifying capacity and stability of potato proteins and their derived peptides. Finally, it highlights chemical modifications, such as acylation, succinylation, phosphorylation, and glycation to enhance emulsifying capacity and stability. This review provides insight into future research directions for utilizing potato proteins as sustainable protein sources and high-value food emulsifiers, thereby contributing to adding value to the potato processing industry.

Synthesis of Linoleic Acid of Conjugated Isomers from Sesame (Sesamum Indicum) Seed Oil: Its Use and Effect in a Microstructured Product Type Oil-in-Water Emulsion

The development of functional foods is an area of great interest and innovation in the food industry. The use of conjugated linoleic acid (CLA) in food formulations has been growing in recent years due to its multiple health benefits. In this study, conjugated linoleic acid was obtained from sesame oil, and its use in the formulation of oil-in-water food emulsions was evaluated. Conjugated linoleic acid (CLA) was synthesized from the linoleic acid present in sesame oil using the alkaline isomerization method using proplyeneglycol as a solvent. The effect of alkali concentration (NaOH) and reaction time on the conversion of linoleic acid to CLA was evaluated. A 96.6% conversion of CLA was obtained with a NaOH concentration of 7% and a reaction time of 2 h. Emulsions were prepared using CLA as oil phase and soy lecithin, tween 80, carboxymethylcellulose as emulsifying agents. Emulsions with mixtures of carboxymethylcellulose and tween 80 were stable, presenting a non-Newtonian fluid behavior of pseudoplastic type (n&lt;1). The Ostwald-de-Waele model shows an optimal fit to the experimental data of apparent viscosity (R2&gt;0.99 ), and its microstructural characterization shows a homogeneous particle distribution. These results show that the alkaline isomerization process using propylene glycol as a solvent is an excellent alternative for the synthesis of CLA from vegetable oils such as sesame oil and its application in the development of microstructured products such as functional emulsions, and their subsequent application in the development of new food products with beneficial health characteristics.

Recent Progress, Application, and Quality Evaluation of Plant-Based Double Emulsions in Low-Fat Foods

Recent Progress, Application, and Quality Evaluation of Plant-Based Double Emulsions in Low-Fat Foods

Mung bean protein pre-fibrils are superior than the mature fibrils in stabilizing HIPEs and controlling the lipid digestion to inhibit in vivo adipose accumulation

Excessive consumption of lipids is one of the major reasons for the prevalence of obesity. Interfacial engineering of food emulsions is highly expected to control the digestion and absorption of lipids, consequently to inhibit adipose expansion. However, this strategy is restricted mainly due to the lack of effective food emulsifiers. In the present study, the mung bean protein fibrils with short worm-like morphology were demonstrated to have superior capabilities than the mature ones in stabilizing high internal phase emulsions (HIPEs) and consequently inhibiting the lipid digestion to control in vivo adipose accumulation. The short worm-like pre-fibrils showed a faster adsorption kinetics to the oil/water interface to reduce the interfacial tension to a substantially lower level compared with the mature fibrils. The HIPEs stabilized by the worm-like pre-fibrils showed a wider range of oil phase volume fractions and protein fibril concentrations, which showed the characteristic connected polygon oil droplets network microstructure due to the squeezing of oil droplets. In comparison, the HIPEs stabilized by the mature mung bean protein fibrils were unstable, undergoing ostwald ripening with the appearance of big oil droplets shortly after the preparation. Consequently, significantly less free fatty acids were released from the HIPEs stabilized by the worm-like pre-fibrils compared with the mature ones in the in vitro stimulating digestion assay. Interestingly, compared with the HIPEs emulsified by the mature amyloid-like fibrils (HIPEs-M group), long-term oral administration of mice with the HIPEs stabilized by the worm-like pre-fibrils (HIPEs-W group) resulted in significantly lower body weight and substantially inhibited adipose expansion. The genes related to lipolysis were over-expressed and the expression of the lipogenesis genes were down-regulated in adipose tissue in HIPEs-W group compared with those in HIPEs-M group. Furthermore, fecal lipid content in HIPEs-W group was higher than that in HIPEs-M group; and the expression of genes related to lipid adsorption in intestine, such as FATP4, FABP-1, PPAR-α, MTTP-1 and CPT1A was down-regulated. Therefore, restriction of lipid digestion and absorption in intestine could serve as the mechanism for the inhibition of in vivo adipose expansion caused by the HIPEs stabilized by the worm-like fibrils compared with the mature fibrils.

Combined effects of high hydrostatic pressure and pulsed electric fields on quinoa starch: Analysis of microstructure, morphology, thermal, and pasting properties

The aim of this study was to evaluate the impact of non-thermal methods, using high hydrostatic pressure (HHP) and pulsed electric field (PEF), on the dual modification of quinoa starch and to analyze the microstructural, morphological, thermal, pasting, and texture properties. Starch was treated with HHP at 400 MPa for 10 min, while PEF was applied using voltages of 10 and 30 kV cm−1 for a total time of 90s. The modification techniques were effective in breaking down amylose molecules and amylopectin branches, where for the dual treatment, higher values of DP6–12 were found. The average diameter and gelatinization temperatures were elevated after HHP, thus forming clusters that require more energy for paste formation. The use of 30 kV cm−1 and 400 MPa (HP30) in starch facilitates the creation of new food products with better texture, stability and nutritional value, making them suitable for use in food emulsions and the cosmetics industry.

Improvement of NaCas/DGMO complex emulsion on resveratrol stability, in vitro bioaccessibility, in vivo bioavailability and gut microbiota

Evaluation for biological impact of food emulsions is fundamental for their application. In present study, we utilized a NaCas-DGMO (sodium caseinate-decylglycerol monooleate) stabilized emulsion to improve resveratrol's (Res) stability, and bioavailability. The in vivo interaction between complex emulsion and gut microbiota was further explored. Results indicated NaCas-DGMO emulsion achieved a loading rate of 92 % for Res and significantly enhanced storage and photo stability of Res. In vitro gastrointestinal digestion highlighted a significant improvement in Res's bioaccessibility. In vivo pharmacokinetic tests showed a notable 3.1-fold increase in oral bioavailability, with a prolonged Tmax of 6 h post-administration. Gut microbiota analysis revealed that the emulsion promoted beneficial bacteria, like Blautia, which produce short-chain fatty acids. Consequently, the findings proved potential of NaCas-DGMO stabled emulsion as carriers for bioactive substances in the food industry. The innovative methodology employed in assessing biological effects provides valuable insights for future research in related field.

Effect of pH and sodium ion on the interfacial adsorption abilities and emulsion stability of soy hull polysaccharide

To investigate the effect of ionic strength and pH on the interfacial adsorption capacity and emulsion stability of soy hull polysaccharide (SHP), a series of SHP emulsions with 10% oil content was prepared with 0–0.30 mol/L Na+ at pH 3.0 and 5.0. The results of droplets size, zeta potential, dilatational rheological, and cryo-scanning electron microscopy analyses showed that the droplets of the emulsion at pH 3.0 were smaller and the system was more stable than at pH 5.0, and Na+ effectively shielded the negative charge on the SHP surface, leading to more SHP adsorption to the interface and increasing viscosity; whereas too much Na+ weakened the repulsive forces between droplets, making it easier for the droplets to merge with each other and causing emulsion destabilization. The best emulsification capacity of SHP was achieved at pH 3.0 with 0.10 mol/L Na+, in which 58.62 ± 0.49% SHP would adsorb to the interface, and kept high zeta potential of interface with −30.00 ± 0.27 mV. Meanwhile, the emulsion prepared under this condition had good storage stability and exhibited small droplet size of 2.425 ± 0.004 µm after 30 days. In conclusion, above indicators demonstrated that SHP-stabilized emulsions were influenced by pH and Na+, this provides theoretical and practical support for selecting the most suitable acid-base and ionic environment to prepare food emulsion by SHP, or other anionic polysaccharides.

4D printing of Pickering emulsion: Temperature-driven color changes

Pickering emulsion inks were employed to demonstrate the temperature-driven 4D printing method. The Pickering emulsion consisted of water phase containing NaHCO3 and oil phase containing curcumin. Upon heating, the movement of pigment molecules was induced, resulting in color changes. The formation mechanism, rheological properties, printing properties and color changes of Pickering emulsion as well as the release kinetic mechanism of curcumin were investigated. The results indicated that relationships were also established between quantified color values (L*, a*, b*) and heating time. Moreover, the release of the curcumin in the Pickering emulsion, which was designated as a swelling process, followed the non-Fickian mechanism due to the occurrence of diffusion and erosion. The Hixson-Crowell model exhibited the highest linearity (R2: 0.9430 to 0.9825) of Pickering emulsions. In conclusion, the research offers a new perspective for the development of personalized Pickering emulsion food with bright colors.

Enzymatically and chemically starch nanoparticles preparation using ultrasonication, precipitation and lyophilization post-treatments: Screening and characterization

Starch nanoparticles (SNPs) have been used in food emulsions as natural stabilizer and emulsifier. SNPs in colloidal form were produced using enzymatically, acidic and alkaline hydrolyses in combination to ultrasonication and precipitation methods. X-Ray diffraction test for produced SNPs indicated that enzymatically and acidic prepared SNPs had amorphous structure while, the resulted SNPs using alkaline hydrolysis had lower relatively crystallinity. Results indicated that, enzymatically prepared SNPs, had minimum particle size (225 ± 10 nm) and polydispersity index (0.472 ± 0.05), and maximum zeta potential (−26.3 ± 1 mV), antioxidant activity (3.36 ± 0.05 %) and specific surface area (1.8 ± 0.1 m2g−1). Transmission electron microscopy revealed that prepared SNPs had spherical shape and enzymatically prepared SNPs had mean particle size of <100 nm. SNPs in powder form were prepared using freeze drying (pressure and temperature of 100 Pa and − 70 °C). Atomic force microscopy results demonstrated that starch granules had smooth surface, with polyhedral shape and particle size ranging 5 to 25 μm, and after hydrolysis, SNPs had particle size in nanometer scale. Emulsion ability test indicated that oil separation time from the prepared emulsions containing 10 % (W/V) starch, and enzymatically, acidic and alkaline prepared SNPs powder were 41, 70, 82 and 101 s, respectively.

How can food frequency questionnaire evaluate the intake of processed foods with added emulsifiers? A pilot study

SummaryEmulsifiers are widely used by food manufacturers, and their consumption has been linked to adverse health outcomes. The average dietary intake of emulsifiers has been poorly reported because no dietary assessment tool is yet available to determine their qualitative or quantitative intake. The present study aimed to validate a newly developed food frequency questionnaire (FFQ) for assessing the intake of foods with added emulsifiers. A cross‐sectional study was conducted on a sample of healthy female adults living in Saudi Arabia. All participants completed the FFQ alongside 3‐day food records (Reference method). Pearson's correlation test, cross‐classification analysis and weighted kappa (κw) statistics were used to assess the validity of the new FFQ against the reference method. The results showed variation in relative validity and level of agreement of food items and/or groups consumption between the two methods. Correlation coefficient values ≥0.5 were reported for some food items (i.e., condensed/evaporated milk, packaged powdered soup/broths and vegetable/nut purees). The FFQ demonstrated an acceptable degree of agreement between the two methods for the confectionery, dairy products and ‘other foods’ with ≥50% of participants classified into the same tertile by both methods (κw = 0.2–0.48). However, poor agreement outcomes were found with bakery products, processed meats and beverages with &lt;50% of participants classified in the same tertile (κw &lt; 0.2). The present study indicated that the new FFQ is a suitable qualitative tool for assessing intakes of food emulsifiers. However, the tool still needs further validation.

Modulation of rapeseed protein nanoparticles by interaction with chitosan: Enhancing the physical stability, antioxidant activity and β-carotene slow-release properties of Pickering emulsion

This study aimed to investigate the physical stability, oxidation, digestibility and β-carotene sustained-release properties of Pickering emulsions stabilized by rapeseed protein (RP) complexed with chitosan (CS). The results showed that adding CS to RP decreased the RP mean particle size from 3575.0 to 130.9 nm, increased its zeta-potential from 29.6 to 41.4 mV, changed its tertiary structure, and enabled its uniform dispersion. Additionally, CS addition improved RP interfacial properties at air/water and oil/water interfaces, thereby enhancing its emulsification activity and stability. Rheological property analysis exhibited that RP/CS complex had a smaller storage modulus (G′) and loss modulus (G") as well as a higher apparent viscosity. Moreover, the RP/CS complex stabilized emulsions showed a smaller average particle size of 100–1500 nm, a higher zeta-potential of 58–66 mV and better physical stability, thus better tolerating environmental factors such as time, temperature and salt ions. Furthermore, the RP/CS complex stabilized emulsions showed better antioxidant properties with a lower peroxide value (POV) and thiobarbituric acid reactant value (TBARS). Finally, the RP/CS complex emulsions exhibited better antidigestive stability and could slow down the β-carotene release rate. These results provide a theoretical basis for the application of RP/CS complex as a new food emulsifier in the nanocolloid transport system.

Tribological properties of real foods using extended Stribeck curves and their relationship with nutritional and rheological parameters.

The tribological properties of 19 commercial food products, grouped into six categories (yogurt, dressings, spreads, porridges, emulsified sauces, and syrups) were investigated in relation to their rheological (dynamic oscillatory shear test) and nutritional properties (fat, carbohydrate, and protein). A tribological system (a glass ball and three polydimethylsiloxane pins) generated the extended Stribeck curve, monitoring friction factors (f) over an extended range of sliding speed (v) (10-8 to 100 m/s). Tribological parameters (f, v) at four inflection points dividing the frictional regimes (X1, breakaway point between the static and kinetic regimes; X1-X2, boundary; X2-X3, mixed; X3-X4, hydrodynamic regimes) and the slope between X3 and X4 (s) were subjected to principal component analysis and hierarchical clustering on principal components, using rheological and nutritional parameters as quantitative supplementary variables. Tribological patterns were predominantly influenced by viscosity, viscoelasticity, yield stress, fat content, and the presence of particles (e.g., sugar, proteins, and fibers) and pasting materials (e.g., starches and modified starches). The 19 tribological patterns were classified into 3 clusters: low f and s for fat- and/or viscoelastic-dominant foods (Cluster 1), low f and high s for food emulsions and/or those with low extent of shear-thinning (Cluster 2), and high f at the boundary regime either for the most viscous foods or for those in the presence of particulates (Cluster 3). These results suggest that the compositional and rheological properties have a more profound impact on the classification of complex tribological patterns than the categories of food products.