Influence of freezing temperature and maltodextrin concentration on stability of linseed oil-in-water multilayer emulsions

Preparation and characterization of astaxanthin-loaded microcapsules stabilized by lecithin-chitosan-alginate interfaces with layer-by-layer assembly method

Astaxanthin is a kind of keto-carotenes with various health benefits. However, its solubility and chemical stability are poor, which leads to low bio-availability. Microcapsules have been reported to improve the solubility, chemical stability, and bio-availability of lipophilic bioactives. Freeze-dried astaxanthin-loaded microcapsules were prepared by layer-by-layer assembly of tertiary emulsions with maltodextrin as the filling matrix. Tertiary emulsions were fabricated by performing chitosan and sodium alginate electrostatic deposition onto soybean lecithin stabilized emulsions. 0.9 wt% of chitosan solution, 0.3 wt% of sodium alginate solution and 20 wt% of maltodextrin were optimized as the suitable concentrations. The prepared microcapsules were powders with irregular blocky structures. The astaxanthin loading was 0.56 ± 0.05 % and the encapsulation efficiency was >90 %. A slow release of astaxanthin could be observed in microcapsules promoted by the modulating of chitosan, alginate and maltodextrin. In vitro simulated digestion displayed that the microcapsules increased the bio-accessibility of astaxanthin to 69 ± 1 %. Chitosan, alginate and maltodextrin can control the digestion of microcapsules. The coating of chitosan and sodium alginate, and the filling of maltodextrin in microcapsules improved the chemical stability of astaxanthin. The constructed microcapsules were valuable to enrich scientific knowledge about improving the application of functional ingredients.

Freeze-thaw stability of Pickering emulsion stabilized by modified soy protein particles and its application in plant-based ice cream

Pickering emulsions are of great interest to the food industry and their freeze-thaw stability important when used in frozen foods. Particles of soybean isolate (SPI) were heat treated and then crosslinked with transglutaminase (TG) enzyme to produce Pickering emulsions. The protein particles produced using unheated and uncrosslinked SPI (NSPI) was used as the benchmark. The mean particle size, absolute zeta potential, and surface hydrophobicity of protein particles produced using heat treatment and TG crosslinking (at 40 U/g) SPI (HSPI-TG-40) were the highest and substantially higher than those produced using NSPI. The thermal treatment of protein particles followed by crosslinking with TG enzyme improved the freeze-thaw stability of Pickering emulsions stabilized by them. The Pickering emulsions produced using HSPI-TG-40 had the lowest temperature for ice crystal formation and they had better freeze-thaw stability. The plant-based ice cream prepared by HSPI-TG-40 particle-stabilized Pickering emulsions had suitable texture and freeze-thaw stability compared to the ice cream produced using NSPI. The Pickering particles produced using heat treatment of SPI followed by crosslinking with TG (at 40 U/g) produced the most freeze-thaw stable Pickering emulsions. These Pickering particles and Pickering emulsions could be used in frozen foods such as ice cream.

Research progress of starch as microencapsulated wall material

Starch is non-toxic, low cost, and possesses good biocompatibility and biodegradability. As a natural polymer material, starch is an ideal choice for microcapsule wall materials. Starch-based microcapsules have a wide range of applications and application prospects in fields such as food, pharmaceuticals, cosmetics, and others. This paper firstly reviews the commonly used wall materials and preparation methods of starch-based microcapsules. Then the effect of starch wall materials on microcapsule properties is introduced in detail. It is expected to provide researchers with design inspiration and ideas for the development of starch-based microcapsules. Next the applications of starch-based microcapsules in various fields are presented. Finally, the future trends of starch-based microcapsules are discussed. Molecular simulation, green chemistry, and solutions to the main problems faced by resistant starch microcapsules may be the future research trends of starch-based microcapsules.

Effect of ultrasonication on emulsion formulation, encapsulation efficiency, and oxidative stability of spray dried chia seed oil

Present study was conducted to develop a stable chia oil emulsion using an ultrasound emulsification technique. Whey protein concentrate, gum Arabic, and xanthan gum stabilized layer by layer chia oil emulsion was developed using an electrostatic deposition. Single-layer and multilayer emulsion of chia oil was developed and their stability is compared. Developed emulsions were characterized by viscosity, stability, surface charge, and droplet size. Layer-by-layer emulsion showed the highest stability (98%) among all the formulations developed. Formulated single-layer and double-layer emulsions were spray dried and the respective powders were characterized for bulk density, tapped density, Hausner ratio, Carr's index, moisture content, color values, encapsulation efficiency, peroxide value, XRD, and SEM. Multilayer emulsion-based powder showed better flowability properties. The encapsulation efficiency of multilayer microparticles was found to be 93% with the lowest peroxide value of 1.08 mEq O2/kg fat. XRD diffractogram of the developed microparticles revealed amorphous nature. The developed ultrasound layer-by-layer emulsification technique is an efficient technique for developing chia oil-loaded microparticles.

Effects of Glucose and Corn Syrup on the Physical Characteristics and Whipping Properties of Vegetable-Fat Based Whipped Creams

The aim of this work is to evaluate the effects of glucose and corn syrup on the physical characteristics and whipping properties of whipped creams. The interfacial protein concentration and apparent viscosity of emulsions increased with an increasing sugar concentration. In whipped creams, a shorter optimum whipping time (top), higher fat coalescence degree, higher firmness and higher stability were detected as sugar concentration increased. The partial coalescence degree, overrun and firmness of whipped cream with 30 wt% glucose reached 76.49%, 306% and 3.82 N, respectively, significantly (p < 0.05) higher than those (67.15%, 235% and 3.19 N) with 30 wt% corn syrup. Compared with glucose at the same sugar concentration, higher interfacial protein concentration and less-shaped aggregates and coalescences were observed for the emulsions upon the addition of corn syrup, which caused a lower degree of fat coalescence and a lower firmness of whipped cream. The differences could be explained by the presence of maltodextrin (MDX) in corn syrup, which protects absorbed protein throughout freezing and retards the formation of a continuous network during whipping. As a result, the addition of sugars could well improve stability of emulsion, firmness and foam stability of whipped cream efficiently. With a 25−30 wt% sugar addition, even if there was a lower partial coalescence degree and firmness compared with glucose, whipped cream with corn syrup exhibited relatively good stability. These results suggest that MDX improves the stability of emulsion and, thus, has a potential use in low-sugar whipped cream.

MCT/LCT Mixed Oil Phase Enhances the Rheological Property and Freeze-Thawing Stability of Emulsion

The main objective of this study was to investigate the effect of different oil phase compositions (medium-chain triglyceride (MCT) and long-chain triglyceride (LCT), the proportion of MCT is 0%, 5%, 10%, 15% and 20%, respectively) on the rheological properties and freeze-thaw stability of emulsions. The emulsions were characterized by differential scanning calorimetry (DSC), rheometer, stability analyzer, Malvern particle size meter and confocal microscope. Results showed that all emulsions exhibited a gel-like characteristic with a storage modulus higher than the loss modulus. The elastic modulus and complex viscosity of the emulsions increased with the increase of MCT proportions. During the heating from 4 °C to 80 °C, the complex viscosity of all emulsions decreased first and then remained unchanged at a continuous high temperature, indicating that the emulsions had good stability and internal structural integrity during the cooling and high-temperature processes. With the increase of MCT proportions, the freeze-thaw stability of the emulsions increased first and then decreased, and showed the optimum with 10% MCT. That could be referred for the production of a product with better freeze-thaw stability and rheological property in the food and cosmetic industries.

Effect of preparation procedure on properties of egg white protein and the fibrous microparticle stabilized complex emulsions

This study, three different procedures were used for preparation of egg white protein (E) and egg white protein fibrous microparticle (EM) complex emulsions, to modify the interfacial and aqueous composition. According to the adding order of EM and E during emulsification, the emulsions were named as type I (EM and E mixed firstly, followed by emulsification), type II (emulsified with EM firstly, followed by the addition of E) and type III (emulsified with EM firstly, followed by the addition of E). The particle size, creaming stability at various salt concentration, elastic module (G'), and lipid oxidation degree were investigated. The results showed that, EM at interface is beneficial for improving salt resistance of the complex emulsions, while E was more effective in terms of preventing oxidation of oil, attributed to the possibility to form continuous elastic interface film. The type III complex emulsion at EM:E ratio of 2:1 showed both improved creaming and oxidation stability, behaving the potential to be used as carrier of lipo-nutrients.

Development of Salt- and Gastric-Resistant Whey Protein Isolate Stabilized Emulsions in the Presence of Cinnamaldehyde and Application in Salad Dressing

Protein-stabilized emulsions tend to be susceptible to droplet aggregation in the presence of high ionic strengths or when exposed to acidic gastric conditions due to a reduction of the electrostatic repulsion between the protein-coated droplets. Previously, we found that incorporating cinnamaldehyde into the oil phase improved the resistance of whey protein isolate (WPI)-stabilized emulsions against aggregation induced by NaCl, KCl and CaCl2. In the current study, we aimed to establish the impact of cinnamaldehyde on the tolerance of WPI-stabilized emulsions to high salt levels during food processing and to gastric conditions. In the absence of cinnamaldehyde, the addition of high levels of monovalent ions (NaCl and KCl) to WPI-emulsions cause appreciable droplet aggregation, with the particle sizes increasing from 150 nm to 413 nm and 906 nm in the presence of NaCl and KCl, respectively. In contrast, in the presence of 30% cinnamaldehyde in the oil phase, the WPI-emulsions remained stable to aggregation and the particle size of emulsions kept within 200 nm over a wide range of salt concentrations (0-2000 mM). Divalent counter-ions promoted droplet aggregation at lower concentrations (≤20 mM) than monovalent ones, which was attributed to ion-binding and ion-bridging effects, but the salt stability of the WPI emulsions was still improved after cinnamaldehyde addition. The incorporation of cinnamaldehyde into the oil phase also improved the resistance of the WPI-coated oil droplets to aggregation in simulated gastric fluids (pH 3.1-3.3). This study provides a novel way of improving the resistance of whey-protein-stabilized emulsions to aggregation at high ionic strengths or under gastric conditions.

Electrolysis soy protein isolate-based oleogels prepared with an emulsion-templated approach

This research focuses on the use of protein-polyphenol complex and protein-polyphenol: polysaccharide complexes to prepare oleogels through an emulsion-templated approach. Electrolysis soy protein isolate (ESPI) could be effectively adsorbed on the surface of a single-layer emulsion to increase the particle size. The order of the negative charges of the emulsion after adding polysaccharides was xanthan gum (XG)> pectin> carboxymethyl cellulose (CMC). Rheological behavior showed that the stability of the double-layer emulsions increased, and the viscoelasticity increased around one order of magnitude with the addition of polysaccharides. The oil binding capacity (OBC) of the oleogel prepared by adding polysaccharides increased to more than 97%. The peroxide value (PV) and anisidine value (AV) of XG oleogel were the minimum values in all samples. The AV and POV were within the regulatory limits of China after storage for 21 days. This provides a reference to design of ESPI-based oleogel for different applications.

Towards the systematic design of multilayer O/W emulsions with tannic acid as an interfacial antioxidant

This work discusses the possibility of designing multilayer oil-in-water emulsions to introduce the maximum possible amount of an antioxidant at the droplet interfaces for the optimal protection of a linseed oil core against oxidation, using a systematic three-step colloidal procedure. An antioxidant (here Tannic Acid - TA) is chosen and its interactions with a primary emulsifier (here Bovine Serum Albumin - BSA) and several polysaccharides are first examined in solution using turbidity measurements. As a second step, LbL deposition on solid surfaces is used to determine which of the polysaccharides to combine with BSA and tannic acid in a multilayer system to ensure maximum presence of tannic acid in the films. From UV-vis and polarization modulation infrared reflection-absorption (PM-IRRAS) spectroscopic measurements it is suggested that the best components to use in a multilayer emulsion droplet, together with BSA and TA, are chitosan and pectin. BSA, chitosan and pectin are subsequently used for the formation of three-layer linseed oil emulsions, and tannic acid is introduced into any of the three layers as an antioxidant. The effect of the exact placement of tannic acid on the oxidative stabilization of linseed oil is assessed by monitoring the fluorescence of Nile red, dissolved in the oil droplets, under the attack of radicals generated in the aqueous phase of the emulsion. From the results it appears that the three-stage procedure presented here can serve to identify successful combinations of interfacial components of multilayer emulsions. It is also concluded that the exact interfacial placement of the antioxidant plays an important role in the oxidative stabilization of the valuable oil core.

Preparation of functional rice cake by using β-carotene-loaded emulsion powder

The purpose of this study was to apply a powdered β-carotene-loaded emulsion to a real food product, Korean traditional rice cakes (Garaedduk). β-Carotene was incorporated into the oil phase of a sodium caseinate-stabilized emulsion. Emulsion powder containing β-carotene was prepared using freeze-drying, and maltodextrin and gum arabic were used as wall materials. Oil/protein/maltodextrin weight ratios of 3:1:2 and 3:1:5 (core-to-wall ratios of 1:1 and 1:2) were used, and gum arabic was added by replacing the amount of maltodextrin for 0.1%, 0.2%, and 0.5% w/w. Manufactured emulsion powders prepared with wall material at a core-to-wall ratio of 1:2 remained stable after reconstitution in terms of particle diameter and ζ-potential. The encapsulation efficiency of the emulsion powder increased by 90% in the presence of maltodextrin at a core-to-wall ratio of 1:2. Garaedduk containing the emulsion powder was then manufactured and it was confirmed that β-carotene was not degraded during the manufacturing process of Garaedduk by using HPLC. The results from this study may be useful for rational designing of functional foods with lipophilic bioactive materials.

Carboxymethyl chitosan-decorated proliposomes as carriers for improved stability and sustained release of flaxseed oil

A flaxseed oil carboxymethyl chitosan-decorated proliposome system was fabricated in this research. The physicochemical characteristics, stability, and in vitro release behaviors of flaxseed oil were studied and compared with that of flaxseed oil-loaded liposomes. The results of dynamic light scattering, transmission electron microscopy, and oxidation stability indicated that the storage stability of proliposomes was better. After 28 days of storage, the peroxide value of flaxseed oil-loaded liposomes (20.1 meq/kg) was significantly (P < 0.05) higher than that of flaxseed oil-loaded proliposomes (9.0 meq/kg); the thiobarbituric acid reactive substances in the former (0.53 mmol/kg) was also higher than that in the latter (0.27 mmol/kg). The in vitro release behavior of flaxseed oil indicated the proliposomes were more stable in the simulated gastrointestinal fluids. Therefore, the flaxseed oil-loaded proliposome system could be a promising vehicle for delivery flaxseed oil in food industry. PRACTICAL APPLICATION: A flaxseed oil-loaded proliposome delivery system was fabricated in this research. Their physical and oxidation stability of flaxseed oil were improved, and the in vitro cumulative release of flaxseed oil was delayed compared with flaxseed oil liposomes. This system may provide an effective strategy for the flaxseed oil encapsulation in the food industry.

Effects of Molecular Weight and Guluronic Acid/Mannuronic Acid Ratio on the Rheological Behavior and Stabilizing Property of Sodium Alginate

The aim of this study was to prepare sodium alginates (SAs) with different molecular weight and G/M ratio, and characterize their rheological behaviors and emulsifying properties. The result of Fourier transform infrared (FTIR) showed that the chemical bonds among the β-d-mannuronic acid- (M-), α-l-guluronic acid- (G-), and MG-sequential blocks in the SA chains were not changed significantly by acid treatment. Meanwhile, the molecular weight and G/M ratio of the SA exhibited drastic variation after acid modification. The result of rheological analysis suggesting that the apparent viscosity of SA reduced from 30 to 16.4 mPa.s with the increase of shear rate, reveals that SA solution belongs to pseudoplastic liquid. Also, the apparent viscosity of acid-modified SA solution dropped rapidly with the decrease of the molecular weight. The properties of emulsions stabilized by SA, SA-Ms, and commercial SAs were evaluated via the interface tensiometry and determination of the zeta potential, droplet size, creaming index (CI), and Turbiscan stability index (TSI). Compared with the SA-stabilized emulsion, the interfacial tension of the emulsion stabilized by SA-M increased with the decrease of the molecular weight reduced at the similar M/G ratio. The decrease in zeta potential and the increase in TSI of the emulsion were observed with the decrease of molecular weight, indicating that molecular weight plays an important role on the emulsifying ability of SA. In addition, the SA with low G/M ratio can form emulsions with stable and fine droplets.

Effect of Emulsifier Type, Maltodextrin, and β-Cyclodextrin on Physical and Oxidative Stability of Oil-In-Water Emulsions

The effect of emulsifiers, emulsion stabilizer (maltodextrin, MD), and β-cyclodextrin (BCD) on physical and oxidative properties of oil-in-water (O/W) emulsions (5%, 20%, 40% of oil, w/w) was investigated. Four different emulsifiers were selected based on their structure: two types of protein-based emulsifiers (sodium caseinate, SC; and whey protein isolate, WPI), and two types low molecular weight emulsifiers (LMEWs: lecithin, LEC; and Citrem, CITREM). Physical and oxidative stability of emulsions prepared with these emulsifiers together with MD were compared based on their creaming index (CI), viscosity, droplet size, zeta potential, peroxide and p-anisidine values. LMWE-stabilized emulsions (with LEC or CITREM) had better creaming stability with lower droplet sizes whereas protein-stabilized emulsions (with SC or WPI) had higher viscosities. Droplet size was the lowest when CITREM was used, which increased with increasing oil concentration for all emulsifiers. Formulation with the lowest CI value and droplet size was considered to be more prone to oxidation; therefore, a 1:1 (w/w) combination of CITREM with BCD was used to stabilize the emulsions to improve the oxidative as well as physical stability. Added BCD significantly increased the storage stability of emulsions by reducing CI and droplet size values with a simultaneous increase in the viscosity, both at room temperature and at storage conditions (at 4 and 55 ^o C). However, the oxidative as well as physical stability of BCD added emulsions were not improved, neither toward heat- nor light-induced lipid oxidation. PRACTICAL APPLICATION: This work investigated the effects of emulsifiers and dextrins on the stability of oil-in-water (O/W) emulsions. Both maltodextrin (MD) and β-cyclodextrin (BCD) addition resulted in enhanced physical stability, the latter being more effective. The findings can be applied to formulate emulsions with improved shelf life within the limits of allowed daily intake (ADI) level of BCD (5 mg/kg bw per day).

Ultrasound-assisted preparation of flaxseed oil nanoemulsions coated with alginate-whey protein for targeted delivery of omega-3 fatty acids into the lower sections of gastrointestinal tract to enrich broiler meat

Flaxseed oil is one of the richest sources of α-linolenic acid (ALA). However, the susceptibility of ALA to oxidation and also lack of the convenient methods to deliver these invaluable compound into the lower sections of gastrointestinal tract (GIT) are still unknown. The objective of the current study was to establish a method for ALA targeted delivery into the lower sections of GIT to enrich broiler meat. An in vitro study was performed to use ultrasound to produce oil-in-water nanoemulsions of flaxseed oil stabilized by different wall materials for controlled release of ALA in GIT. The fabricated nanoemulsions were assessed in terms of particle size distribution, zeta-potential, encapsulation efficiency, field emission scanning electron microscopy (FESEM), and in vitro gastric and intestinal digestions. Results indicated that the nanoemulsions coated by a combination of whey protein-sodium alginate (WP/SA) had a relatively uniform distribution and all particles distributed in less than 1000 nm. The values of zeta-potential for nanoemulsions stabilized by whey protein (WP), sodium alginate (SA) and WP/SA were -31.4, -29.3 and -45.5 mV, respectively. The wall combination of WP/SA showed the best encapsulation efficiency followed by WP. The FESEM results indicated spherical and non-aggregated structures for three types of nanoemulsions. The nanoemulsions stabilized by WP/SA showed a high resistance to in vitro gastric digestion but a relatively rapid release during intestinal digestion. An in vivo study was conducted to enrich broiler meat with ALA, using the best wall material from the in vitro study. In total, 300 one-day-old broilers (Ross, 308) were assigned into 5 experimental treatments including: basal diet (BD), basal diet plus flaxseed oil (BD + FO, 1 mL/kg body weight), basal diet plus ultrasonicated flaxseed oil nanoemulsions stabilized by WP/SA (BD + FON, 1 mL/kg body weight), basal diet plus flaxseed oil and vitamin E (BD + FO + E, 1 mL/kg body weight and 200 mg/kg diet vitamin E) and basal diet plus ultrasonicated flaxseed oil nanoemulsions stabilized by WP/SA and vitamin E (BD + FON + E, 1 mL/kg body weight of nanoemulsion and 200 mg/kg diet vitamin E). Each experimental treatment included 4 replicates in a completely randomized design. Results showed a better feed conversion ratio (FCR) in birds treated with dietary treatments compared with those received basal diet. A greater incorporation of ALA and total poly unsaturated fatty acids (PUFA) omega-3 were observed in thigh and breast meat of birds fed by ultrasonicated flaxseed oil nanoemulsions. In comparison to birds fed with BD, a favourably lower PUFA omega-6/omega-3 ratio was observed in birds received nanoemulsions of flaxseed oil. In general, the current study showed that using ultrasound to produce nanoemulsions stabilized by WP/SA has potential to protect ALA of flaxseed oil from gastric digestion and could be used as delivery carriers of ALA omega-3 fatty acid to the posterior sections of chicken GIT. Moreover, ultrasonic fabrication of nanoemulsion has potential to enrich broiler meat by ALA fatty acid.

Designing biopolymer-coated Pickering emulsions to modulate in vitro gastric digestion: a static model study

The aim of this study was to restrict the degree of gastric destabilization of Pickering emulsions by using electrostatic deposition of a biopolymeric layer at the proteinaceous particle–laden oil–water interface.

Kinetic Analysis of Freeze-Thaw Stability of Mayonnaise

Kinetic analysis was used to study the destabilization of mayonnaise by focusing on the fat crystals. Mayonnaise prepared from rapeseed oil and soybean oil was stored at temperatures ranging from −20 to −40 °C. The destabilization kinetic parameters were measured by observing oil separation over time. The destabilization rate constant, kd, increased with decreasing temperature. The highest value of kd was 1.28 × 10−3 min−1 at −40 °C for rapeseed oil mayonnaise (RoM) and the lowest was 1.95 × 10−6 min−1 at −20 °C for soybean oil mayonnaise (SoM). At each temperature, the kd value in RoM was higher than that in SoM. However, the order of destabilization, n, followed no specific pattern. The crystallization rate constant, Kc, and Avrami constant, n, were calculated using microscopic images of the fat crystals. The increase in crystallization kinetic parameters with decreasing temperature revealed changes in crystal behavior. Both the destabilization rate constant, kd, and the crystallization rate constant, Kc, depended on the temperature. This temperature dependency behavior showed a correlation between kd and Kc, suggesting that the destabilization rate depended on the rate of growth of fat crystals during the freeze-thawing of mayonnaise.

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

For the first time sodium alginate is used to improve the stability of oil body emulsions against salt, pH and freeze–thaw cycling.

The Influence of Maltodextrin on the Physicochemical Properties and Stabilization of Beta-carotene Emulsions

Beta-carotene is important for fortification of nutritional products while its application is limited by instability. The influence of maltodextrin (MDX) on physicochemical properties and stability of beta-carotene emulsions stabilized by sodium caseinate (SC) was investigated. The emulsions were characterized by dynamic light scattering (DLS), laser diffraction (LD), transmission electron microscopy (TEM), rheometer, and turbiscan lab expert. The effects of pH, ionic strength, and freeze-thaw on stability of emulsions were observed. The emulsions could tolerate up to 2 mol/L NaCl or 10 mmol/L CaCl₂ and showed Newtonian behavior. The droplet diameter, polydispersity index, and zeta-potential did not change obviously after 3 months storage at 4°C in dark conditions. The emulsions with MDX showed excellent freeze-thaw stability and gave favorite protection for beta-carotene. The retention ratio of beta-carotene in the emulsions with MDX was above 92.1% after 3 months storage while that in the one without MDX was only 62.7%. The study may provide a promising strategy to improve stability of sensitive nutraceuticals without adding synthetic antioxidants. The findings obtained could provide fundamental basis for rational design of emulsion delivery systems when freeze-thawing is required during manufacturing process or storage period.

Influence of morphology and polymorphic transformation of fat crystals on the freeze-thaw stability of mayonnaise-type oil-in-water emulsions

This study examined the destabilization of an oil-in-water (O/W) emulsion by freeze-thawing with a focus on the influence of the morphology and polymorph of fat crystals. For a model of food emulsion, this study used a mayonnaise-type O/W emulsion containing 70wt% canola oil (canola emulsion) or soybean oil (soybean emulsion) stored at -15, -20, and -30°C. The freeze-thaw stabilities of the emulsions were evaluated by measuring the upper oil layer after freeze-thawing. The soybean emulsion kept at -20°C had the highest stability; the other emulsions were destabilized during 6h of storage. Crystallization in the emulsions was determined using differential scanning calorimetry (DSC), time variation of temperature, X-ray diffraction measurement, and polarized light microscopy. DSC thermograms indicated that crystallization in emulsions occurred first in the high-melting fraction of oil, followed by water and, last, in the low-melting fraction of oil during cooling to -40°C. In the canola emulsion, the amount of fat crystals derived from the low-melting fraction of oil increased during storage at all temperatures, resulting in partial coalescence. The soybean emulsion was expected to be destabilized by polymorphic transformation (sub-α to β' and β) of fat crystals derived from the high-melting fraction during storage at -15 and -20°C. However, the soybean emulsion did not exhibit polymorphic transformation stored at -30°C, and the amount of fat crystals did not increase during freezing; thus, it was destabilized via a different mechanism.