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In this study, the rice protein (RP) fractions (albumin, globulin, glutelin, and prolamin) in rice bran were obtained through the sequential extraction method using 2% (w/w) NaCl, 0.1 N NaOH, and 70% (w/w) ethanol and the proportions of water-soluble protein fractions (albumin) were compared among different degrees of milling (DM; 3%, 5%, 7%). The three types of bran showed different chemical components and populations of the four RP fractions. The 7% DM of brown rice is the stage at which the bran layers are completely removed and white rice is produced. In the 7%-DM bran, the content of water-soluble albumin was the highest. The extracted RP fractions contained eight essential amino acids and among them, albumin had the highest content of lysine. The secondary structures measured by circular dichroism spectroscopy were rich in alpha-helices. These results provide basic data for the extraction and utilization of water-soluble proteins from rice bran.

Dispersion of rice protein (RP) at a neutral pH is highly important for its application in the food industry. We analyzed the solubility of RP at different pH conditions and found higher solubility at pH 8 than at a neutral pH. Furthermore, at pH 2, the RP solubility improved from 30 to 63% with sonication; however, the samples precipitated when the pH was increased from 2 to 7. To circumvent this, anionic pectin and sodium alginate were added to the RP solution at pH 2. Pectin formed a complex with RP at pH 2, showing a shift in the zeta-potential from 17.3 mV (RP only) to − 1.0 mV (RP plus 1% pectin). Interestingly, the formation of this RP-pectin complex allowed RP to remain dispersed when the pH was increased to 7. Moreover, a stable emulsion could be prepared using the RP-pectin complex as an emulsifier.

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.

The phenolic compounds (PCs) abundant in fruits and vegetables are easily browned by oxygen and browning enzymes, with subsequent destruction of nutrients during food processing and storage. Therefore, natural anti-browning additives are required to control these reactions. The aim of the present study was to investigate the feasibility of cycloamylose (CA) complexation as a way to improve stability of PCs against oxidation and browning enzymes. The complex was prepared by reacting enzymatically produced CA with a degree of polymerization of 23–45 with PCs in aqueous solution. No significant differences were observed between the PCs and their CA complexes in 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging experiments. However, the reduction rate of their antioxidant activity was clearly reduced in the presence of CA for as long as 4 weeks. At the studied concentrations, the activity of polyphenol oxidase on all of the tested PC species was inhibited in the presence of CA, although this effect was less evident as the substrate concentration increased. The higher the CA concentration added to apple juice, the lower the variation in the total color difference (ΔE*) during storage, confirming that CA could be used as an effective natural anti-browning agent. Our study is the first to study the potential of CA as a natural material for browning control. The results obtained will provide useful information for active food applications requiring oxidative stability in fruit products.

Photosensitizers conjugated with hyaluronic acid via disulfide linkers were developed for biologically activatable near-infrared fluorescence imaging and photodynamic therapy. The nanoparticles prepared from the conjugate are nonfluorescent and nonphototoxic in their native state, but become highly fluorescent and phototoxic in response to reductive agents inside cancer cells.

This study was performed to examine the effect of emulsifiers used to coat emulsion droplets containing β-carotene on the behavior of lipid digestion and bioaccessibility. Different emulsifiers (whey protein isolate, soy protein isolate, sodium caseinate, Tween 20, and soy lecithin) were used to prepare emulsions with similar sized droplets (200–400 nm). Protein-stabilized emulsions showed a similar behavior of digestion, and morphological change in the simulated gastrointestinal conditions. Soy lecithin-stabilized emulsions showed the lowest rate and extent of lipid digestion probably due to the low emulsifying capability of soy lecithin, showing coalesced droplets occurring after exposure to the gastric phase. Tween 20-stabilized emulsions had a lower rate and extent of lipid digestion than that of protein-stabilized emulsions, even though Tween 20-stabilized emulsions had a more stable structure to resistant to aggregation in gastric phase. Even though the difference in the digestion rate and extent, β-carotene bioaccessibility was not significantly different among emulsions stabilized by different emulsifiers at p

The aim of this study was to examine the effects of xanthan gum on the lipid digestibility, rheological properties, and β-carotene bioaccessibility of rice starch-based filled hydrogels. β-Carotene was solubilized within lipid droplets of emulsion that were then entrapped within rice starch hydrogels fabricated with different concentrations of xanthan gum. At a low concentration of xanthan gum (

The effect of simulated mastication (size reduction and α-amylase addition) on lipid digestion and β-carotene bioaccessibility of starch-based filled hydrogels was examined. The mechanical aspects of mastication were simulated by pureeing the hydrogel samples (semi-solid pieces) for 2 min using a mortar and pestle to mimic the chewing process. The microstructure, lipid digestion, and β-carotene bioaccessibility of the filled hydrogels were then measured as the samples were passed through simulated oral, gastric, and small intestinal phases. A filled hydrogel that was not subjected to simulated mastication in the oral phase had small and evenly distributed lipid droplets in the oral and gastric phases, regardless of the presence or absence of α-amylase. However, the lipid droplets in filled hydrogels that were subjected to simulated mastication became aggregated, especially after exposure to α-amylase. There were also appreciable differences in the initial rate of lipid digestion and in carotenoid bioaccessibility depending on whether or not simulated mastication was employed. These results suggest that the mechanical processing of the hydrogels in the simulated oral phase plays an important role in determining their subsequent gastrointestinal fate.

Rosemary extract (RE) has significant antioxidant and antibacterial properties; however, the application of RE to areas with an aqueous solution is limited due to its poor solubility. There is a need for research focused on finding a method to improve water solubility for incorporating RE into aqueous systems, such as food and cosmetic. Therefore, in this study, the micellar solubilization of RE is conducted using four types of surfactants (Tween 20, polyglyceryl-10-laurate, polyglyceryl-10-myristate, and polyglyceryl-10-monooleate) to increase the water solubility of RE and the effects of various surfactant types and concentration on solubility were investigated. Antibacterial activities of the mixture solutions containing RE and surfactants were also examined. The water solubility of RE significantly improved when surfactants were added into the RE solution and especially in polyglyceryl-10-monooleate, with the longest tail, was the most effective for increasing solubility. In terms of the antibacterial effect on Bacillus subtilis, it was observed that a relatively lower concentration of surfactants was effective. The results of this study provide useful information for the development of a new RE-loaded delivery system for food and cosmetic application.

A whey protein isolate–rhodamine B conjugate (WPI-RB) was synthesized to visualize changes in the location of a protein emulsifier in oil-in-water emulsions during digestion. An oil-soluble dye (Nile Red) was used to visualize changes in the lipid phase during digestion. Protein-labeled and lipid-labeled emulsions were passed through a simulated gastrointestinal tract consisting of mouth, stomach, and intestinal phases, and changes in protein and lipid location and morphology were monitored using confocal laser scanning microscopy. The proteins remained attached to the lipid droplet surfaces in the mouth and stomach, but formed large aggregates in the small intestine. The lipid droplets were highly flocculated in the mouth, highly coalesced in the stomach, and fully digested in the small intestine. Our results show that conjugation of fluorescence dyes to protein emulsifiers is useful for direct visualization of their location, as well as for understanding the behavior of food emulsions within the gastrointestinal tract.

We investigated the molecular characteristics of 4-α-glucanotransferase (4αGTase)-modified rice starch (MRS) and corn starch (MCS) gels and the NaCl release properties depending on their mechanical properties. Also, encapsulation efficiency (EE) and oil globule size of water-in-oil-in-water (W/O/W) emulsions containing MRS or MCS in the inner aqueous phase (W1) with NaCl as a model core material were measured after preparation and 14 days of storage. The characteristics of MRS and MCS were examined by analyzing amylose content, molecular fine structure, microstructure, and mechanical properties to better understand their associations with emulsion stability. At 20 % concentration, the gel strength of MCS (~105 pa) was greater than that of MRS (~103 pa) as MCS had higher apparent amylose content than MRS. The rate of NaCl release from the gel was highly correlated with the gel strength that depended on the type and concentration of the enzymatically-modified starch. As the gel strength increased, EE of freshly prepared and stored W/O/W emulsions increased. Osmotic swelling of NaCl-containing W/O/W was significantly reduced with the incorporation of the modified starch gels in W1 phase. These results indicated that physicochemical properties of 4αGTase-modified starch gels in W/O/W emulsions largely affected the encapsulation efficiency and stability of the emulsions, which could be utilized to formulate W/O/W emulsions with improved stability and the potential for broader applications.

There is considerable interest in controlling the gastrointestinal fate of nutraceuticals to improve their efficacy. In this study, the influence of methylcellulose (an indigestible polysaccharide) on lipid digestion and β-carotene bioaccessibility was determined. The carotenoids were encapsulated within lipid droplets that were then loaded into rice starch hydrogels containing different methylcellulose levels. Incorporation of 0 to 0.2% of methylcellulose had little impact on the dynamic shear rheology of the starch hydrogels, which may be important for formulating functional foods with desirable textural attributes. The microstructure, lipid digestion, and β-carotene bioaccessibility of the filled hydrogels were measured as the samples were passed through simulated oral, gastric, and small intestinal phases. The lipid digestion rate and carotenoid bioaccessibility decreased with increasing methylcellulose. This effect was attributed to the ability of the methylcellulose to inhibit molecular diffusion, promote droplet flocculation, or bind gastrointestinal components thereby inhibiting triacylglycerol hydrolysis at the lipid droplet surfaces. This information may be useful for rationally designing functional foods with improved nutritional benefits.

Waxy and non-waxy rice starches from japonica type Korean rice varieties were esterified with different levels of octenyl succinic anhydride (OSA), and the molecular structure of amylopectin (AP), digestibility, and emulsion stability were investigated. As OSA levels increased, the degree of substitution, granule size, peak and final viscosities, emulsion stability, and short chain of AP increased. However, the gelatinization temperature and enthalpy, and digestibility decreased. All OSA esterified starches showed a new band at 1723 cm&minus, 1, but maintained A-type crystallinity. The DP6-12 of AP in waxy rice starch (WRS) was higher than that in non-waxy rice starch (NRS) with increasing OSA levels. Because the amylose and long chain of AP accessed easily with OSA groups, the digestibility of NRS was lower than that of WRS. The emulsion stability was higher in WRS than in NRS. From the above results, it is suggested that amylose should have a higher affinity with OSA esterification than AP and that the emulsion stability should increase in WRS, but the digestibility should decrease in NRS after OSA modification.

The molecular structures of non-waxy rice starches purified from three Korean rice cultivars, Dongjin1, Hopyeong, and Ilmi, were investigated to determine the main reasons why it is difficult to make manju with Dongjin1 flour compared to other rice flours with similar processing qualities. The molecular structural characteristics of the three rice starches were analyzed by high-performance size-exclusion chromatography and high-performance anion-exchange chromatography. The Dongjin1 starch had lower molecular weight (MW) amylose, a smaller proportion of short a chains, and higher average amylopectin branch chain length than the other two starches. These properties of Dongjin1 starch resulted in a lower water binding capacity, lower swelling power at 80 °C, and lower peak viscosity than those of the other two starches. It is suggested that the MW of amylose and degree of polymerization of amylopectin are important factors to make gluten-free bakery products using non-waxy rice flours.

The emulsifying properties of rice proteins isolated from various non-waxy and waxy rice cultivars were studied to evaluate their potential application as oil-in-water (O/W) emulsifier and to compare the emulsifying properties of the rice proteins isolated from various rice cultivars. The solubility of the rice proteins was measured at different pHs (2–10), and O/W emulsions were prepared with the proteins at pH 2, 7, and 10. The rice protein-stabilized O/W emulsions were analyzed by measurement of particle size and zeta-potential, and observation under an optical microscope. The results indicated the potential of the rice proteins as emulsifiers at low and high pH values, and that, in particular, rice proteins isolated from waxy-rice cultivars could form stable emulsions even at neutral pH. The information obtained in this study may be useful for development of emulsion-based food products using rice protein isolate.

Hydrolysis of the oil phase in a water-in-oil-in-water (W/O/W) emulsion was studied using pancreatic lipase. The influence of the W/O volume fraction, lipase concentration, and concentration of emulsifiers used to prepare W/O/W emulsions on lipid digestion and release of encapsulated material were investigated. The extent of lipid digestion differed depending on the W/O volume and lipase concentration, and the amount of dye released was not dependent on the W/O content or lipase concentration. The concentration of emulsifiers did not affect the extent of digestion. The information obtained in this study will be useful for design of W/O/W emulsion formulations with controlled release profiles and lipid digestion.

This study was performed to examine the stability of retinol contained within oil-in-water (O/W) emulsions under UV and during storage at different temperatures. O/W emulsions were prepared using different emulsifiers and oil concentrations. The stability of the retinol contained in the O/W emulsions was investigated by measuring the percentage of residual retinol in the samples after UV exposure and storage at different temperatures (4, 25, and 40 °C). The oil concentration of the emulsion had a greater impact on UV stability than the type of emulsifier used, whereas the storage stability at different temperatures was affected by both the choice of emulsifier and the oil concentration. The storage stability of the retinol contained in the O/W emulsions may be related to the lipid oxidation properties of the emulsions rather than the latter’s physical stability. Experiments with EDTA and different oil types were performed to confirm this theory.

The aim of this study was to prepare starch-based filled hydrogels fortified with a model lipophilic nutraceutical (β-carotene) and determine the influence of starch type (mung bean or rice starch) and surfactant type (whey protein isolate (WPI) or Tween 20 (T20)) on lipid digestibility and β-carotene bioaccessibility. Microstructure, lipid digestion, and β-carotene bioaccessibility were measured as the emulsions and filled hydrogels were passed through a simulated gastrointestinal tract that included oral, gastric, and intestinal phases. The bioaccessibility was defined as the fraction of β-carotene solubilized within the mixed micelle phase after lipid digestion. Non-encapsulated T20-stabilized emulsions had better aggregation stability than WPI-stabilized emulsions under simulated gastrointestinal conditions, which led to a higher β-carotene bioaccessibility. Both Tween 20- and WPI-stabilized emulsions incorporated in starch-based filled hydrogels led to high lipid digestion and β-carotene bioaccessibility. The release behavior of free fatty acids during lipase digestion depended on the type of starch used as a hydrogel matrix, which was attributed to differences in starch structure. The information obtained in this study may be useful for the fortification of starch-based gelled products with lipophilic nutraceuticals.

The effect of roasting on particle size distribution, water-holding capacity, and viscosity of sunsik was investigated in this study using non-roasted one as control. Roasting increased the size of particles in sunsik, in particular, particles larger than 1 μm in diameter, indicating that roasted sunsik is likely to sediment faster, thereby decreasing the time to maintain dispersibility when mixing with water. Roasting also increased the water-holding capacity of sunsik, indicating that polymerization occurred greater than a pyrolysis during roasting, leading to increased viscosity in roasted sunsik. These results indicate that the roasting affected the dispersibility and viscosity of sunsik by increasing particle size and water-holding capacity, respectively.

A gel-based encapsulation system was developed by incorporating W/O/W emulsions and 4-α-glucanotransferase (4αGTase) treated starch capable of thermoreversible gel formation, and its physical and release characteristics were investigated as functions of preparation conditions and temperature. Release properties of the W/O/W gels were affected by stability and encapsulation efficiency (EE) of W/O/W emulsions embedded within. Lower EE caused by longer sonication time increased fast release dye portion, which resulted in higher dye release rate, even though emulsion stability improved at longer sonication time. Lower dye release rate of W/O/W gels prepared with relatively higher W/O volume fractions slightly increased as temperature increased from room temperature to 90 °C. However, samples prepared with relatively lower W/O volume fractions showed higher dye release rate and a larger increase at 90 °C. The 4αGTase-treated starch gel improved W/O/W emulsion stability and thus retarded dye release even at 90 °C.

Extended Abstract There is considerable interest in controlling the gastrointestinal fate of nutraceuticals to improve their efficacy [1]. In this study, the influence of methylcellulose (an indigestible polysaccharide) on lipid digestion and β-carotene bioaccessibility was determined. The carotenoids were encapsulated within lipid nanodroplets that were then loaded into rice starch hydrogels containing different methylcellulose levels. Incorporation of 0 to 0.2% of methylcellulose had little impact on the dynamic shear rheology of the starch hydrogels, which may be important for formulating functional foods with desirable textural attributes. The microstructure, lipid digestion, and β–carotene bioaccessibility of the filled hydrogels were measured as the samples were passed through simulated oral, gastric, and small intestinal phases. The lipid digestion rate and carotenoid bioaccessibility decreased with increasing methylcellulose. This effect was attributed to the ability of the methylcellulose to inhibit molecular diffusion, promote droplet flocculation, or bind gastrointestinal components thereby inhibiting triacylglycerol hydrolysis at the lipid droplet surfaces. This information may be useful for rationally designing functional foods with improved nutritional benefits.

The modified starch gels prepared from partial enzyme treatments (1, 3, and 6 U/g starch; 2-h incubation) of the corn and rice starch pastes using Thermus aquaticus 4-α-glucanotransferase (TAαGT) were investigated for their molecular characteristics, microstructures, and physicochemical properties. Unlike the native and partially modified normal starches, the native and partially modified waxy starches could not form gels strong enough for textural analysis after 24 h for gel setting. Features of the partially modified normal starches were the specific apparent amylose contents and maximum iodine absorption wavelength ( λ max , ∼567 nm), as well as the tri-modal molecular weight profiles and flatter side-chain distributions. Also, the partially modified normal starch gels possessed fractured surfaces with discontinuous crystalline fibrous assembly that differed from the native starch gels’ porous continuous network, which resulted in more brittle, rigid, and resilient gels compared with the native gels.

Three types of emulsions (β-Lg-, β-Lg-pectin-, and β-Lg-ι-carrageenan-coated emulsions) with controlled electrostatic and/or steric interactions were prepared, and then examined for their freeze-dry stability in the absence or presence of 6% maltodextrin (MD). In the absence of MD, all emulsions were highly unstable to freeze-drying, nevertheless, the β-Lg-pectin-coated emulsions (d 32 =5.37, d 43 =35.11 μm) that were stabilized mostly by steric repulsion showed better stability than the other 2 emulsions (no dried power was obtained). The freeze-dry instability of all emulsions was improved with MD addition, particularly in the β-Lg- (d 43 =1.10 μm) and β-Lg-ι-carrageenan-coated emulsions (d 43 =0.58 μm) that were stabilized by electrostatic repulsive force. In the presence of MD, the β-Lg-ι-carrageenan-coated emulsions showed the highest stability to freeze-drying, which was attributed to the cooperative impact of steric and electrostatic repulsion. This study implicates that the major mechanism for stabilizing emulsions against freeze-drying could be different depending on the absence or presence of MD.

Reduced-fat sausages were prepared by replacing pork back fat with barley flours of different particle sizes. Three barley flour fractions with different particle size were obtained by passing the ground barley material through a sieve. Fraction 1 and 2 had a higher water absorption index than other fraction and showed higher peak and final viscosities due to higher β-glucan content. Therefore, fraction 1 and 2 were used as a fat replacer in preparation of reduced-fat sausages. Response surface methodology was employed to optimize the formulation of reduced-fat sausage and the effects of fat content and barley flour paste concentration on the textural properties were analyzed simultaneously. Using a regression model, the optimum formulation of reduced-fat sausage was calculated. For fraction 1, calculated levels of fat content and paste concentration were 7.6 and 3.9%, and for fraction 2, levels were 6.7 and 6.9%, respectively.

The influences of maltodextrin (MD) addition and multi-layer formation on the freeze-thaw stability of β-lactoglobulin (β-Lg)-stabilized oil-in-water beverage emulsions (0.1 wt% corn oil, 0.006 wt% β-Lg) were investigated. Various beverage emulsions were prepared depending on MD concentration (0–20 wt%), its dextrose equivalent (M150 or M250), and the presence or absence of additional polysaccharides (pectin, alginate, or ι-carrageenan) coatings around the emulsion droplets. All emulsions (β-Lg- and β-Lg-polysaccharide-coated emulsions) were unstable to experimental freeze-thaw cycling in the absence of MD. In the presence of MD, all emulsions containing M250 had better stability to droplet aggregation than those with M150, regardless of MD concentrations and freeze-thawing. The optimum concentrations of M250 required to prevent emulsions destabilization under the freeze-thawing were 6, 15, and 2% for β-Lg-, β-Lg-ι- carrageenan-, and β-Lg-pectin-coated emulsions, respectively. This study implicates practical information to improve freeze-thaw stability of some beverage emulsion products that inevitably go though freezing during processing.

Useful materials can be made from cycloamylose (CA) and the functional properties of CA could be improved by complexation with surfactants. Isothermal titration calorimetry (ITC) was used to investigate interactions between CA and surfactants in buffered solutions. Three surfactants with C12 non-polar tail groups and charged [anionic: sodium dodecyl sulfate (SDS); cationic: dodecyl trimethylammonium bromide (DTAB)] or non-charged headgroups [non-ionic: polyoxyethylene 23 lauryl ether (Brij35)] were used in this study. The effects of temperature, pH, and salt concentration were also studied. All three surfactants bound to CA; however, Brij35 binding to CA was negligible. Enthalpy changes associated with binding of surfactants to CA were exothermic except for interactions measured at 50 °C. There was no effect of pH on surfactant demicellization or CA binding. Salt concentration affected surfactant demicellization, but the amount of SDS bound to CA at saturation was unaffected by salt. When the titration curves obtained for CA with SDS and DTAB were fitted, it could be analyzed using a model based on a single set of identical sites.

The impact of freezing–thawing and freeze–drying on the physical stability of oil-in-water (O/W) emulsions containing protein-coated and protein/polysaccharide-coated droplets has been studied. O/W emulsions (2 wt% corn oil, 0.12 wt% β-lactoglobulin, pH 3.5) were prepared that contained either 0 or 0.2 wt% pectin or ι -carrageenan, and 0–8 wt% maltodextrin. The emulsions were then subjected to either freeze–thaw cycling (−20 °C, 22 h; +30 °C, 2 h; ×2) or freeze–drying and reconstitution (pH 3.5). The stability of the emulsions to freeze–thaw or freeze–dry processing was then analyzed using particle size, microstructure, and creaming stability measurements. All emulsions were unstable to these processes in the absence of maltodextrin, which was attributed to extensive droplet aggregation during freezing and/or dehydration. In the presence of maltodextrin, the emulsions containing polysaccharide coatings had better stability to droplet aggregation after freeze–thaw cycling and freeze–drying than emulsions containing no polysaccharides. Specifically, considerably less maltodextrin was required to form stable emulsions when the polysaccharide coatings were present. We propose that the anionic polysaccharides formed a protective layer around the lipid droplets that improved their stability to freeze–thaw cycling and freeze–drying.

The objective of this study was to investigate the influence of interfacial composition on the in vitro digestion of emulsified lipids coated by various emulsifiers by pancreatic lipase. Sodium caseinate, whey protein isolate (WPI), lecithin and Tween 20 were used to prepare corn oil-in-water emulsions (3 wt% oil). Pancreatic lipase (1.6 mg/mL) and/or bile extract (5.0 mg/mL) were added to each emulsion and the particle charge, droplet aggregation, microstructure and free fatty acids released were measured. In the absence of bile extract, the amount of free fatty acids released per unit volume of emulsion was much lower for lipid droplets coated by Tween 20 (13 ± 16 μmol ml−1) than those coated by lecithin (75 ± 20 μmol ml−1), sodium caseinate (220 ± 24 μmol ml−1) or WPI (212 ± 6 μmol ml−1). In the presence of bile extract, there was an appreciable increase in the amount of free fatty acids released in all the emulsions, with the most appreciable effects being observed in the Tween 20-stabilized emulsions. The stability of the emulsions to droplet flocculation and coalescence during hydrolysis was also strongly dependent on emulsifier type, with the WPI emulsions being the least stable and the Tween 20 emulsions being the most stable. Our results suggest that the access of pancreatic lipase to emulsified fats decreases in the following order: proteins (caseinate and WPI) > phospholipids (lecithin) > non-ionic surfactants (Tween 20). These results may have important consequences for the design of foods with either increased or decreased lipid bioavailability.

Low-fat spreads were developed using a thermoreversible gelling agent, the 4-α-glucanotransferase (4αGT)-modified rice starch. The low-fat spreads consisted of the modified starch paste (or rice starch or maltodextrin), olive oil (0-30% w/w), egg yolk, salt, xanthan gum, and butter flavor, and were produced by homogenization, ultrasonic processing at 50% amplitude for 2min, and cold-gel setting at 4°C for 24h. Formulations with 15% and 20% of the modified starch paste resulted in highly stable oil-in-water low-fat spreads having varied textural properties and acceptable spreadability, whereas formulations with rice starch and maltodextrin did not yield enough stability and consistency. Moreover, the modified starch-based low-fat spreads showed high thermoreversibility. These results indicated that 4αGT-modified starch could be used in the preparation of low-fat spreads, allowing the formulation of functional products for healthy diets.

The purpose of this study was to create water-in-oil (W/O) and water-in-oil-in-water (W/O/W) emulsions containing gelled internal water droplets. Twenty weight percent W/O emulsions stabilized by a nonionic surfactant (6.4 wt % polyglycerol polyricinoleate, PGPR) were prepared that contained either 0 or 15 wt % whey protein isolate (WPI) in the aqueous phase, with the WPI-containing emulsions being either unheated or heated (80 degrees C for 20 min) to gel the protein. Optical microscopy and sedimentation tests did not indicate any significant changes in droplet characteristics of the W/O emulsions depending on WPI content (0 or 15%), shearing (0-7 min at constant shear), thermal processing (30-90 degrees C for 30 min), or storage at room temperature (up to 3 weeks). W/O/W emulsions were produced by homogenizing the W/O emulsions with an aqueous Tween 20 solution using either a membrane homogenizer (MH) or a high-pressure valve homogenizer (HPVH). For the MH the mean oil droplet size decreased with increasing number of passes, whereas for the HPVH it decreased with increasing number of passes and increasing homogenization pressure. The HPVH produced smaller droplets than the MH, but the MH produced a narrower particle size distribution. All W/O/W emulsions had a high retention of water droplets (95%) within the larger oil droplets after homogenization. This study shows that W/O/W emulsions containing oil droplets with gelled water droplets inside can be produced by using MH or HPVH.

The objective of this study was to investigate the influence of interfacial composition and electrical charge on the in vitro digestion of emulsified fats by pancreatic lipase. An electrostatic layer-by-layer deposition technique was used to prepare corn oil-in-water emulsions (3 wt% oil) that contained droplets coated by (1) lecithin, (2) lecithin–chitosan, or (3) lecithin–chitosan–pectin. Pancreatic lipase (1.6 mg mL−1) and/or bile extract (5.0 mg mL−1) were added to each emulsion, and the particle charge, droplet aggregation, and free fatty acids released were measured. In the presence of bile extract, the amount of fatty acids released per unit amount of emulsion was much lower in the emulsions containing droplets coated by lecithin–chitosan (38 ± 16 μmol mL−1) than those containing droplets coated by lecithin (250 ± 70 μmol mL−1) or lecithin–chitosan–pectin (274 ± 80 μmol mL−1). In addition, there was much more extensive droplet aggregation in the lecithin–chitosan emulsion than in the other two emulsions. We postulated that lipase activity was reduced in the lecithin–chitosan emulsion as a result of the formation of a relatively thick cationic layer around each droplet, as well as the formation of large flocs, which restricted the access of the pancreatic lipase to the lipids within the droplets. Our results also suggest that droplets initially coated by a lecithin–chitosan–pectin layer did not inhibit lipase activity, which may have been because the chitosan–pectin desorbed from the droplet surfaces thereby allowing the enzyme to reach the lipids; however, further work is needed to establish this. This information could be used to create food emulsions with low caloric level, or to optimize diets for individuals with lipid digestion problems.

The influence of the nature of the interfacial membrane on the kinetics of droplet growth in hydrocarbon oil-in-water emulsions was investigated. Droplet growth rates were determined by measuring changes in the droplet size distribution of 1 wt % n-tetradecane or n-octadecane oil-in-water emulsions using laser diffraction. The interfacial properties of the droplets were manipulated by coating them with either an SDS layer or with an SDS-chitosan layer using an electrostatic deposition method. The emulsion containing SDS-coated octadecane droplets did not exhibit droplet growth during storage for 400 h, which showed that it was stable to Ostwald ripening because of this oils extremely low water-solubility. The emulsion containing SDS-coated n-tetradecane droplets showed a considerable increase in mean droplet size with time, which was attributed to Ostwald ripening associated with this oils appreciable water-solubility. On the other hand, an emulsion containing SDS-chitosan coated n-tetradecane droplets was stable to droplet growth, which was attributed to the ability of the interfacial membrane to resist deformation because of its elastic modulus and thickness. This study shows that the stability of emulsion droplets to Ostwald ripening can be improved by using an electrostatic deposition method to form thick elastic membranes around the droplets.

β-Carotene was incorporated into three types of delivery system: (i) “emulsions”: protein-coated fat droplets dispersed in water; (ii) “hydrogels”: rice starch gels; and (iii) “filled hydrogels”: protein-coated fat droplets dispersed in rice starch gels. Fat droplets in filled hydrogels were stable in simulated mouth and stomach conditions, but aggregated under small intestinal conditions. Fat droplets in emulsions aggregated under oral, gastric, and intestinal conditions. β-Carotene bioaccessibility was higher when encapsulated in filled hydrogels than in emulsions or hydrogels, which was attributed to increased aggregation stability of the fat droplets leading to a larger exposed lipid surface area. β-Carotene bioaccessibility in starch hydrogels containing no fat was very low (≈1%) due to its crystalline nature and lack of mixed micelles to solubilise it. The information presented may be useful for the design of rice-starch based gel products fortified with lipophilic nutraceuticals.

We have developed an indocyanine green-loaded perfluorocarbon (ICG/PFCE) nanoemulsion as a multifunctional theranostic nanomedicine which enables not only (19)F magnetic resonance (MR)/near-infrared fluorescence (NIRF) bimodal imaging but also subsequent photodynamic/photothermal dual therapy of cancer. The hydrodynamic size of ICG/PFCE nanoemulsions was 164.2 nm. The stability of indocyanine green (ICG) in aqueous solution was significantly improved when loaded on perfluorocarbon nanoemulsions. In addition, ICG/PFCE nanoemulsions showed good dispersion stability in aqueous media containing 10% fetal bovine serum, for at least 14 days. (19)F-MRI of ICG/PFCE nanoemulsions showed that the signal intensity increased with increasing nanoemulsion concentration with no signal observed from the surrounding background. Using NIRF imaging with perfluorocarbon nanoemulsion alone, without ICG, did not produce NIRF, while clear and bright fluorescent images were obtained with ICG/PFCE nanoemulsions at 10-µM ICG equivalent. The capacity of ICG-loaded nanoemulsions to generate heat following light irradiation by using an 810-nm laser was comparable to that of free ICG, while singlet oxygen generation of ICG-loaded nanoemulsions was significantly better than that of free ICG. In vitro cytotoxicity tests and fluorescence microscopy confirmed biocompatibility of the nanoemulsion. Upon light irradiation, U87MG glioblastoma cells incubated with ICG/PFCE nanoemulsions underwent necrotic cell death. The therapeutic mechanism during light illumination appears to be mainly due to the photodynamic effect at lower ICG concentrations, whilst the photothermal effect became more obvious at increased ICG concentrations, enabling combined photodynamic/photothermal therapy of cancer cells.

The physicochemical properties of 4-α-glucanotransferase (4αGTase)-modified rice flours were examined by measuring the molecular weight distribution, moisture sorption isotherm, and melting enthalpy of ice crystals. The results obtained by measuring the moisture sorption isotherm and melting enthalpy of ice crystals revealed that 4αGTase-modified rice flours had high water binding capacity than that of control rice flour. When the textural properties of noodles containing 4αGTase-treated rice flours after freeze-thaw cycling were measured by texture profile analysis, the textural properties of control noodle deteriorated. However, those of noodle with 4αGTase-modified rice flours were retained. For the melting enthalpy of ice crystals formed within cooked noodles, 4αGTase-treated rice flour showed similar effect to sucrose for reducing the melting enthalpy of ice crystals, however, the texture and taste of noodle with sucrose was undesirable for consuming. 4αGTase-treated rice flour appeared to have good potential as a non-sweet cryoprotectant of frozen product.