Soybean Oil Bodies Research Articles

Loading natural emulsions with nutraceuticals by ultrasonication: Formation and digestion properties of curcumin-loaded soybean oil bodies

Curcumin is often used as a natural food additive because of its many drug functions and biological properties; however, its poor water solubility, chemical instability, ease of degradation, relatively high rate of metabolic degradation, and low bioavailability has limited its use in functional foods and medicines. In this study, we prepared curcumin oil body (COB) emulsions by loading curcumin into soybean slurry and explored the structural characteristics of emulsions prepared using different ultrasound sequences with the aim of enhancing the functionality and digestion properties of the oil bodies. The measured encapsulation efficiencies, particle sizes, ζ-potentials, Turbiscan stability indices, and other indicators reveal that the best COB encapsulation efficiency and stability are obtained using two ultrasound treatment methods and the addition of 10% oil. Structural analysis using infrared spectroscopy and sodium dodecyl sulfate–polyacrylamide gel electrophoresis revealed that the curcumin-loaded oil was mainly bound to the hydrophobic area of the protein on the surface of the oil body through hydrophobic interactions. COB stability was found to positively correlate with the amount of extrinsic protein adsorbed on the surfaces of the oil droplets. Digestion data showed that, compared with the method in which the oil body is prepared and then loaded with curcumin (COB–U), the COB prepared by direct ultrasonication in the soybean slurry (U–COB) realizes sustained oil release in the intestine. U–COB also exhibits higher bioavailability (67.42%), which is important for creating a more effective curcumin delivery system.

Enzymatic activity and stability of soybean oil body emulsions recovered under neutral and alkaline conditions: Impacts of thermal treatments

Two soybean oil body (SOB) creams were recovered from soybean at pH 7 and pH 11, respectively, and dispersed in water to obtain a natural 5% o/w emulsion. The lipoxygenase (LOX) activity and oleosin hydrolysis behavior in two SOB emulsions, as affected by different washing times and thermal treatments (50–110 °C), were investigated. The SOB emulsions recovered under neutral conditions (pH 7) were accompanied by strong enzymatic degradation. The absence of LOX and oleosin hydrolase activities was observed in SOB emulsions recovered under alkaline conditions (pH 11). The oxidative and physical stabilities of two SOB emulsions were examined at 37 °C under 15-day storage. Thermal treatment significantly enhanced the oxidative stability of two SOB emulsions due to enzymatic inactivation or altered interfacial properties. Both SOB emulsions exhibited excellent coalescence resistance after the elimination of enzymatic degradation, but their oxidative stability was different. It was due to the modification of the SOB surface by exogenous proteins that accelerated its oxidation. The results of this study might help design highly stable products based on SOB to meet the demand of people for natural products.

Improvement of soybean product flavor and quality as affected by extraction of soybean oil bodies based on a soymilk model system

ABSTRACT Oil bodies (OBs) are lipid-storing organelles of plant seeds; they provide energy for seed germination and seedling growth by oxidative degradation as substrate. Soybean OBs are assumed to be involved in the enzymatic oxidation reaction of volatile flavor formation of soymilk. In order to establish a soymilk model system with soybean OBs as the enzymatic oxidation substrate to study the formation mechanism of soymilk flavor, the effects of extraction times and extraction pH on the composition, particle size and volatile flavor of soybean OBs extracted from raw soymilk were studied. The results showed that most of the extrinsic proteins on the surface of the OBs were removed with increasing extraction times. When the extraction pH increased from 7.0 to 11.0, the relative content of neutral lipids in OBs increased by 6.22%, and the relative content of protein and phospholipids in OBs decreased by 3.23% and 2.88%, respectively. The particle sizes of the OBs gradually decreased from 424 nm to 334 nm. The concentrations of volatile flavor components also gradually decreased from 129.29 μg/L to 52.75 μg/L. The integrity and stability of the OBs were compromised when the extraction pH was ≥12.0. The pH 11.0-OBs were the appropriate substrate for the soymilk model system because of their high purity and stability, better emulsion dispersion stability, and weaker flavor. These results are of great significance for exploring the formation mechanism of soymilk flavor in soymilk model systems to further improve the flavor of soymilk.

Reaction process and characteristic changes in soybean oil bodies during the formation of volatile flavour compounds in soymilk

Reaction process and characteristic changes in soybean oil bodies during the formation of volatile flavour compounds in soymilk

Effect of water bath-assisted water extraction on physical and chemical properties of soybean oil body emulsion.

Soybean oil body (SOB), rich in polyunsaturated fatty acids and biologically active substances, is used as a natural emulsifier in food processing. In addition, SOB is healthier than synthetic emulsifiers. However, the physical and chemical properties of the SOB emulsion directly affect its application in food processing. In order to study the effect of water bath extraction (WBAE) on SOBs, the effects of WBAE method on the composition of SOBs, the zeta potential, average particle size, oxidation stability, and viscosity characteristics of SOB emulsions were researched. It was found that both protein and moisture contents of SOB decreased with increasing WBAE temperature; however, lipid content increased. These results were attributed to the exogenous proteins gradually denatured and dissociated with extraction temperature from 60°C to 100°C. Increasing the extraction temperature, the average particle size of the SOB emulsions increased, the oxidative stability was improved, the Zeta potential and viscosity decreased, and the fluidity of emulsions was improved. The SOB extracted at 100°C has broad application prospects in food, and this research is meaningful for supplying fundamental information for selecting proper extraction temperature of SOBs.

Effects of preheat treatments on the composition, rheological properties, and physical stability of soybean oil bodies

This study investigated the effects of preheat treatments on the composition, rheological properties, and the physical stability of soybean oil bodies and examined the stability of coffee containing those oil bodies. Three preheat treatment methods were compared, including heating (at 65, 75, and 85°C for 30min) of raw soymilk, high-pressure steam heating (at 110, 120, and 130°C for 10 s, ultra high temperature [UHT] treated) of dry soybeans, and milling of soaked soybeans in boiling water. Three UHT samples showed the highest oil body yields (13.59 to 13.87%) and protein yield (2.47 to 3.03%), while oil content in extracts was the lowest (30.97 to 46.25%). Soymilk heated at 65 or 75 °C for 30min showed high oil body extraction yields (13.38 and 11.46%) and the highest oil extraction yields (6.38 to 8.38%) among all the samples. Three UHT samples had a higher average particle size and higher apparent viscosity compared with those of all the other samples. The results from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and particle size distribution suggested heat treatment at 65 to 85 °C just lead to the partially denaturation and unfolding of storage protein instead of severe aggregation, while UHT (samples 5, 6, and 7) could lead to large amount soluble aggregates within oleosins and storage proteins via disulfide bonds. The diluted emulsion with 12% fat content remained stable during a 15-day storage period at 4 °C. The coffee stability of the diluted oil body emulsion indicated high oleosins and low storage protein content in the oil body was a benefit for the coffee stability. PRACTICAL APPLICATION: Soybean oil bodies are natural sources of pre-emulsified oil derived from soybean and can be dispersed in an aqueous medium to form a stable emulsion system. This study provides the foundation for the preparation and application of soybean oil bodies with differing emulsion stabilities and extraction yields in the food industry.

Combinational effects of acid and salt addition on colloidal, interfacial, and emulsifying properties of purified soybean oil bodies

Soybean oil-storing organelles called oil bodies/oleosomes (OBs) are a potential eco-friendly plant-based emulsifier, whereas combinational effects of acid and salt addition on emulsifying properties of OBs were still unclear. This study aimed at investigating colloidal, interfacial, and emulsifying properties of OBs in the presence of acetic acid and NaCl. The purified OBs isolated from soybean seeds were dispersed into 10 mM acetate or phosphate buffer solutions at pH 4.0–7.0 with different NaCl concentrations between 0 and 100 mM. Without added NaCl, the purified OBs were finely dispersed at pH 4.0 and 4.5 by electrostatic repulsion, whereas they aggregated at pH 5.0 and 5.5 probably due to small net charge. The NaCl addition caused screening of the electrostatic interaction between OBs and induced salting-in of OBs. Interfacial tension and interfacial viscoelasticity analyses showed that strongly-charged OBs tended to more slowly sparsely adsorb onto oil-water interface to form less elastic adsorbed layer; this tendency might result from electrostatic adsorption energy barrier between the adsorbed- and non-adsorbed OBs. The OB-stabilized emulsions slightly coalesced under at pH 4.0 and 4.5 without added NaCl probably due to a relatively small amount of the surface protein load. Under all the other tested pH (4.0–7.0) and NaCl (0–100 mM) conditions, the OB-stabilized emulsions were stable against coalescence because of the improved surface load. These results suggest that OBs can be widely applicable for various food emulsions as a potential eco-friendly emulsifier with the appropriate formulation of acid and salt.

The stability and gastro-intestinal digestion of curcumin emulsion stabilized with soybean oil bodies

The study aimed at stabilizing the curcumin emulsions (CEs) using the soybean seed oil bodies (SSOBs) and investigated the gastrointestinal digestion of the CEs. The particle size decreased (P < 0.05) with the increasing concentration of SSOBs from 1.0 wt% to 5.0 wt%. The CEs stabilized with the SSOBs exhibited excellent stability at pH 2.0 and 6.0–10.0. The CEs were stable against the aggregation at 100–500 mmol/L NaCl concentration and elevated temperature. The droplet size analysis and confocal laser scanning microscope observation results indicated that the fat droplets aggregated in the CEs under the gastric conditions at 30 min and afterward it gradually dispersed. Under the simulated intestinal condition, the droplet size of the CEs significantly decreased compared to the simulated gastric conditions (P < 0.05). The release rate of curcumin continuously increased during 180 min digestion under the intestinal conditions. Therefore, SSOBs could be used as the natural emulsifiers and novel carriers in delivering the lipophilic bioactive compounds.

Structure and tribology of κ-carrageenan gels filled with natural oil bodies

Natural oil bodies (OBs) are micron-sized oil droplets found in parts of plants. Due to their nutritional value and characteristic that they are naturally emulsified, OBs have potential applications in food industry. In this study, κ-carrageenan (KC, 1.0 wt %) gels filled with soybean OBs (up to 10 wt % oil content) bound or unbound with the matrix were constructed. Their structure, rheological and tribological properties were characterized. It was found that in the boundary lubrication regime, the lubrication properties of the OB cream and OB emulsion-gels were significantly improved compared with pure water and the KC gels, and are better than the emulsion-gels with medium chain triglycerides (MCT) droplets stabilized by Tween 80. An ultralow boundary friction coefficient (μ) of 0.038 was achieved. The viscosity of the OB cream, the elasticity of the OB emulsion-gels, as well as the ball-bearing and rolling effect of the OBs in and out the gel fragments under shear were believed to contribute to the promising lubrication properties. It was also found that there was no significant difference in μ between the bound and unbound emulsion-gels, although μ of both types of emulsion-gels decreased with increase of oil concentration. The fragmentation and structure failure of the emulsion-gels under shear were believed to weaken the difference.

Effects of soy protein composition in recombined soy-based cream on the stability and physical properties of whipping cream.

Recombinant plant-based whipping cream (RSWC) has been widely studied in recent years. The present study investigated the effects of soybean protein and its hydrolysates on the stability and physical properties of the RSWC. The RSWC was made with 28% soybean oil bodies and 4% additional soy proteins or its hydrolysates. The proteins used were soy protein isolate, 7S, 11S, oil body protein, soybean proteins isolate hydrolyzed by pepsin (SPHPe) and soybean protein isolate hydrolyzed by papain (SPHPa). RSWC made with SPHPa containing a large amount of small-molecule polypeptide had the lowest apparent viscosity, shortest whipping time, best overrun and worst whipping stability, whereas RSWC made with SPHPe containing the α, β subunit and small-molecule polypeptides exhibited the second highest overrun and best whipping stability. The partial coalescence of fat and confocal micrographs of cream emulsions suggested that oil body protein was displaced by the small peptides from the interface, which led to partial destabilization and sufficient coalescence of fat globules after aging and whipping. Selectively hydrolyzed soy protein, such as SPHPe, can be used for the production of RSWC with sufficient overrun and whipping stability. This research is of great significance and opens a route to production of the recombinant plant-based cream in the future. © 2020 Society of Chemical Industry.

Study on the Salad Dressing Based on Natural Oil Body-Sodium Alginate

A new formula of salad dressing using natural soybean oil bodies as replacement of traditional oil and polysaccharide sodium alginate(ALG)as a stabilizer was proposed. Results showed that,the electrostatic interaction between the negatively charged ALG and the positively charged oil bodies improved the dispersibility and stability of the oil bodies. It was found that 0.35% ALG could stabilize 1.0% oil body emulsion well under pH4.5.The in-vitro intestinal digestion measurement found that the free fatty acid release of natural oil body emulsion was lower than that of Tween 80-soybean oil emulsion by about 10%,and ALG further slowed down the initial digestibility speed of the oil bodies. High concentration of ALG(0.5%,0.6%,0.8%,1.0%)could improve the stability of high concentration of oil body emulsion(10.0%,20.0%,30.0%,40.0%),respectively. Taking the market salad dressing as the control,the amount of oil bodies and ALG in salad dressing formula was optimized. The oil body-ALG emulsion containing 60.0%(containing 40.0% oil body and 1.0%ALG)was used in salad dressing formula,and the salad dressing with better viscosity and better stability was obtained. The new salad dressing formula combined health benefits of both soybean oil bodies and sodium alginate,such as low oil content,natural nutrient-rich,slow fat digestion,and could maintain stability during long-term storage.

Effect of NaCl on oxidative stability and protein properties of oil bodies from different oil crops

The objective of this study was to determine the effect of different NaCl (0, 50, 100, 150 and 200 mmol/L) on oxidative stability and protein properties of soybean oil bodies (SBOBs), peanut oil bodies (PNOBs) and sunflower oil bodies (SFOBs) at 25 °C. Results showed that, with the increase of NaCl concentration, ζ-potential values of these three oil bodies (OBs) were decreased significantly and then remained stable, and their particle sizes were slightly increased. NaCl did not significantly influence protein composition and thermal properties of these three OBs, but increased their total ΔH of proteins. With 50 mmol/L of NaCl, hydrophobicity and emulsifying activity (EAI) of SBOBs, PNOBs and SFOBs, and emulsifying stability (ESI) of SBOBs were significantly reduced. When NaCl concentration was more 50 mmol/L, the surface hydrophobicity, emulsifying activity of SBOBs, PNOBs and SFOBs, and emulsifying stability of PNOBs and SFOBs were then gradually increased. Under the accelerated oxidation conditions at 60 °C and when NaCl concentrations was 150 mmol/L, peroxide values of these three OBs were lower than that when NaCl concentration was 50 mmol/L or 100 mmol/L. And thiobarbituric acid values (TBARS) of these three OBs with different NaCl concentrations were all relatively low.

Fabrication and characterization of soybean oil bodies encapsulated in maltodextrin and chitosan-EGCG conjugates: An in vitro digestibility study

Plant lipids are mostly stored in subcellular organelles known as oil bodies (OBs). The aim of this study was to encapsulate soybean OBs by spray-drying, in order to offer a prospective approach to stabilizing OBs, and to provide a novel spray-dried OB product for potential industrial uses. OB emulsions were prepared with different coatings, namely maltodextrin (MD), chitosan (CS), and CS-EGCG covalent conjugates (CSEG), prior to spray-drying. The highest encapsulation efficiency of 96.68% was achieved for MD-CSEG encapsulated OB microparticles. Morphological analysis of spray-dried samples revealed that encapsulating OBs resulted in remarkably reduced microparticle sizes, even after reconstitution. Furthermore, the CSEG provided an even more effective interfacial barrier that protected OB microparticles. In vitro gastrointestinal digestion results revealed that coating OB with MD and CSEG greatly retarded the oil release from 85.2% to 45.3%. This study demonstrated that this novel encapsulation formulation of OBs has the potential to overcome stability drawbacks and minimize the degree of oil release throughout digestion.

Effect of pH on physicochemical properties of oil bodies from different oil crops.

The objective of this study was to determine the effects of pH on the physicochemical properties of soybean oil bodies (SBOBs), peanut oil bodies (PNOBs) and sunflower oil bodies (SFOBs). The mean particle diameter[4,3] (D[4,3]) of oil bodies (OBs) changed to a stationary trend with increased pH. The surface hydrophobicity (H0) of SBOBs, PNOBs and SFOBs significantly decreased with increasing pH 2-12. The emulsifying activity index of SBOBs, PNOBs and SFOBs decreased with increased pH from 2 to 10. The viscosity modulus (G″) value of SBOBs at pH 4 was significantly higher than at pH 7 and pH 9. The initial elastic modulus (G') and G″ values of PNOBs at pH 9 were significantly higher than at pH 4 and pH 7. The G″ values of SFOBs at pH 4 and pH 9 were significantly lower than at pH 7. The steroleosin protein bands of SBOBs significantly decreased at pH 12. The protein bands of PNOBs were reduced at pH 2-4 and pH 10-12, and protein bands decreased most obviously at pH 2. The enthalpy of denaturation (ΔH) values of the oil body (OB) protein at pH 9 were significantly higher than at pH 4 and pH 7. The results showed that the ζ-potential, D[4,3], emulsifying property and H0 of SBOBs, PNOBs and SFOBs were similar to the change of pH value. The three types of OBs have better stability away from the isoelectric point.

Effect of sodium alginate on the stability of natural soybean oil body emulsions.

In this work, the influence of an anionic polysaccharide, sodium alginate (ALG), on the stability of soybean oil body (OB) emulsions under different environmental conditions, including NaCl, pH and freeze–thaw cycling, was studied by analyzing the particle electric charge, particle size and distribution, and using optical and fluorescence microscopy. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the proteins on the surface of oil bodies were mainly oleosins. It was found that ALG can be adsorbed to the surface of oil bodies by strong electrostatic interactions at pH 4.5 and the optimal concentration of ALG was 0.35 wt% for 1 wt% OB emulsions. At pH 4–8, ALG-coated OB emulsions were more stable than uncoated OB emulsions with smaller particle size and more uniform size distribution due to the interaction between OB and ALG. The ALG-coated OB emulsions were also all stable against NaCl within the concentration range of 0–250 mM at pH 7 while uncoated OB emulsions aggregated gradually with the increase of NaCl concentration. For OB emulsions with higher concentration of 10–40 wt% which are frequently used in the food industry, the minimal concentration of ALG required to make stable emulsions was found to be 0.5–1 wt%, correspondingly. Coating oil bodies with ALG also significantly improved the stability of natural oil body emulsions against freeze–thaw cycling, which is of great significance to the further development of natural oil body-based products in food industry.

Soybean P34 Probable Thiol Protease Probably Has Proteolytic Activity on Oleosins.

P34 probable thiol protease (P34) and Gly m Bd 30K (30K) show high relationship with the protease of 24 kDa oleosin of soybean oil bodies. In this study, 9 day germinated soybean was used to separate bioprocessed P34 (P32) from bioprocessed 30K (28K). Interestingly, P32 existed as dimer, whereas 28K existed as monomer; a P32-rich sample had proteolytic activity and high cleavage site specificity (Lys-Thr of 24 kDa oleosin), whereas a 28K-rich sample showed low proteolytic activity; the P32-rich sample contained one thiol protease. After mixing with purified oil bodies, all P32 dimers were dissociated and bound to 24 kDa oleosins to form P32-24 kDa oleosin complexes. By incubation, 24 kDa oleosin was preferentially hydrolyzed, and two hydrolyzed products (HPs; 17 and 7 kDa) were confirmed. After most of 24 kDa oleosin was hydrolyzed, some P32 existed as dimer, and the other as P32-17 kDa HP. It was suggested that P32 was the protease.

Oil Bodies Extracted from High‐Fat and Low‐Fat Soybeans: Stability and Composition During Storage

Soybeans contain oil bodies (OBs) that encapsulate triacylglycerols (TAGs) with a phospholipid monolayer carrying scattered proteins. In nature, soybean OBs can form natural emulsions in aqueous media and may serve as natural, minimally processed, stable, and pre-emulsified oil for addition into appropriate food systems. In this study, OBs were obtained by aqueous extraction from the mature seeds of 2 soybean crop cultivars, high-fat soybean and low-fat soybeans. The compositions of the extracted OBs were analyzed during storage at room temperature up to 14 d (pH = 7). The oxidative stability of these OBs, stored at 60°C, was evaluated by measuring the presence of primary (lipid hydroperoxides) and secondary lipid oxidation products (malondialdehyde) by determining the standard peroxide value (PV) and thiobarbituric acid-reactive substances (TBARS) value. During storage, the contents of unsaturated fatty acids, phospholipids, and tocopherols declined in both OBs, while their mean particle diameters (d32 ) and ζ-potentials increased. The changes in PV and TBARS values exhibited a similar trend for both OBs, but the OBs from low-fat soybeans had significantly lower PV and higher TBARS values than the OBs from high-fat soybean cultivars (P < 0.05). Overall, the OBs from both soybean cultivars had good stability during storage.

Interfacial and emulsifying properties of crude and purified soybean oil bodies

Soybean oil bodies are natural and environment-friendly emulsifying agents from plant resources required as a substitute for emulsifiers such as low-molecular-weight one and animal proteins. The aim of this study was to reveal the interfacial properties and the emulsifying properties of two types of oil bodies extracted from soybean seeds at different pH conditions, that is purified oil bodies (OB) and crude oil bodies (OBC) including storage and other minor proteins. Particle size and zeta-potential measurements and SDS-PAGE revealed that the presence of the involved storage and other minor proteins promoted oil body aggregations and imparted the high zeta-potential to the oil bodies. OB adsorbed onto the oil-water (O/W) interface in closely packed state and formed more elastic adsorbed layer than OBC according to the results from tensiometry. Emulsions stabilized by OB (OB-E) were more stable against oil droplet coalescence than those by OBC (OBC-E) due to the absence of the involved proteins at the emulsion droplet surfaces. Cryo-SEM observation suggests that during emulsification most of the OB and OBC particles adsorbed onto the newly-created O/W interface and then rapidly ruptured.

Physicochemical and rheological properties and oxidative stability of oil bodies recovered from soybean aqueous extract at different pHs

Soybean oil bodies (OBs), naturally pre-emulsified soybean oil, have great potentials to be used in foods and cosmetics. In this study, OBs were recovered from soybean aqueous extract at pH 6.8, 8.0, 9.5, and 11.0, and recovered OBs contained decreased extrinsic protein amount and composition with increasing recovery pH. In unheated condition, particle size and viscosity decreased, whereas isoelectric point (pI) and oxidative stability increased in the order of pH 6.8-, 8.0-, 9.5-, and 11.0-OB. By heating, it was observed that 1) coalescence of OBs occurred in pH 6.8-OB emulsion, but not occurred in pH 11.0-OB emulsion; 2) pIs of all OB emulsions increased; 3) pH 9.5-OB emulsion showed the highest viscosity, followed by pH 8.0- and 6.8-OB, and pH 11.0-OB still showed the lowest viscosity; 4) gels were formed from OB emulsions with solid content of 40% except pH 11.0-OB; 5) oxidative stability was greatly improved for all OB emulsions. This study is meaningful for supplying fundamental information for selecting proper conditions for aqueous extraction of soybean OBs.

The interplay between diverse oil body extracts and exogenous biopolymers or surfactants

Hazelnuts, sesame seeds and soybeans were selected as three diverse sources of oil bodies. Application of aqueous extraction and centrifugation steps resulted in concentrated oil body creams that were studied for their physical stability after dilution to a series of 5.0wt.% oil-in-water emulsions incorporating sodium caseinate (1.0wt.%), Tween 80 (1.0wt.%) or xanthan gum (0.1wt.%). In terms of aggregation/coalescence and creaming, the stability of the oil body based emulsions was ruled to a large extent by the initial natural oil droplet size and the presence of co-extracted exogenous proteins and secondarily by the added biopolymers and the surfactant. More specifically, soybean oil bodies exhibited the highest physical stability, even though incorporation of Tween 80 into all three oil body emulsions improved the stability against aggregation/coalescence, while xanthan gum was an effective stabilizer against creaming.