Droplet Flocculation Research Articles

Novel Oil-in-Water Emulsions Stabilised by Ionic Surfactant and Similarly Charged Nanoparticles at Very Low Concentrations.

Novel oil-in-water (O/W) emulsions are prepared which are stabilised by a cationic surfactant in combination with similarly charged alumina nanoparticles at concentrations as low as 10-5 m and 10-4 wt %, respectively. The surfactant molecules adsorb at the oil-water interface to reduce the interfacial tension and endow droplets with charge ensuring electrical repulsion between them, whereas the charged particles are dispersed in the aqueous films between droplets retaining thick lamellae, reducing water drainage and hindering flocculation and coalescence of droplets. This stabilization mechanism is universal as it occurs with different oils (alkanes, aromatic hydrocarbons and triglycerides) and in mixtures of anionic surfactant and negatively charged nanoparticles. Further, such emulsions can be switched between stable and unstable by addition of an equimolar amount of oppositely charged surfactant which forms ion pairs with the original surfactant destroying the repulsion between droplets.

Influence of oat components on lipid digestion using an in vitro model: Impact of viscosity and depletion flocculation mechanism

Depletion flocculation is a well-known instability mechanism that can occur in oil-in-water emulsions when the concentration of non-adsorbed polysaccharide exceeds a certain level. This critical flocculation concentration depends on the molecular characteristics of the polysaccharide molecules, such as their molecular weight and hydrodynamic radius. In this study, a range of analytical methods (dynamic shear rheology, optical microscopy, and static light-scattering) were used to investigate the interaction between lipid droplets and polysaccharides (guar gum and β-glucans) of varying weight-average molecular weight and hydrodynamic radius, and concentration. The aim of this work was to see if the health benefits of soluble fibers like β-glucans could be explained by their influence on the structure and digestibility of lipid emulsions. The apparent viscosity of the emulsions increased with increasing polysaccharide concentration, molecular weight, and hydrodynamic radius. Droplet flocculation was observed in the emulsions only at certain polysaccharide concentrations, which was attributed to a depletion effect. In addition, the water-soluble components in oat flakes, flour, and bran were extracted using aqueous solutions, to examine their impact on emulsion stability and properties. Then, the rate and extent of lipolysis of a sunflower oil-in-water emulsion in the presence of these oat extracts were monitored using the pH-stat method. However, the inhibition of lipolysis was not linearly related to the viscosity of the oat solutions. The water-soluble extracts of β-glucan collected from oat flakes had a significant inhibitory effect on lipolysis. The results of this study increase our understanding of the possible mechanisms influencing the impact of oat constituents on lipid digestion. This work also highlights the importance of considering the molecular properties of polysaccharides, and not just their impact on solution viscosity.

Encapsulation of vitamin D3 in pickering emulsions stabilized by nanofibrillated mangosteen cellulose: Impact on in vitro digestion and bioaccessibility

Oil-in-water Pickering emulsions stabilized by nanofibrillated cellulose (NFC) were used to encapsulate and deliver vitamin D3. NFC was extracted from a waste product of the food industry, mangosteen (Garcinia mangostana L.) rind, using dissolution in a hot sodium hydroxide solution, bleaching using hydrogen peroxide, and shearing using a high-pressure homogenizer. This yielded cellulose fibers with a diameter of around 60 nm and a length of several micrometers. Emulsions containing 10% w/w oil (0.01% w/w vitamin D3 and 9.99% w/w soybean oil), 0.10–0.70% w/w NFC as emulsifier, and phosphate buffer (pH 7) were prepared. The effect of NFC on lipid digestion and vitamin bioaccessibility was investigated using a simulated gastrointestinal tract (GIT) model, which included mouth, stomach and small intestine phases. The rate and extent of lipid digestion, as well as the vitamin bioaccessibility, decreased with increasing NFC concentration. Numerous physicochemical phenomena may account for this effect, including the ability of NFC to: act as a physical barrier at the lipid droplet surfaces; to promote droplet flocculation in the gastric phase; and, to increase the viscosity of the aqueous phase. The slight decrease in vitamin D3 bioaccessibility at higher NFC levels, was probably due to the lower level of lipid digestion. Our results indicate that mangosteen fiber can be used to stabilize oil-in-water emulsions, and only has a minor effect on lipid digestion and vitamin bioaccessibility when used at relatively low levels. This information may be useful for the rational design of functional foods from natural waste-products, such as mangosteen rind.

Fabrication and Characterization of Quinoa Protein Nanoparticle-Stabilized Food-Grade Pickering Emulsions with Ultrasound Treatment: Interfacial Adsorption/Arrangement Properties.

The natural quinoa protein isolate (QPI) was largely reflected in the nanoparticle form at pH 7.0 (∼401 nm), and the ultrasound at 20 min progressively improved the contact angle (wettability) and surface hydrophobicity of the nanoparticles. Ultrasound process also modified the type of intraparticle interaction, and the internal forces of sonicated particles were largely maintained by both disulfide bonds and hydrophobic interaction forces. In emulsion system, the ultrasound progressively increased the emulsification efficiency of the QPI nanoparticles, particularly at high protein concentration ( c > 1%, w/ v) and higher emulsion stability against coalescence. As compared with the natural QPI-stabilized emulsions, the 20 min sonicated emulsions exhibited higher packing and adsorption at the protein interface. The microstructure of emulsions that occurs is bridging flocculation of droplets at low c (≤1%, w/ v), while the amount of protein particles could be high enough to cover the droplet surface at high c ( >1%, w/ v) with hexagonal array model arrangement. Thus these results illustrated that both natural and sonicated QPI nanoparticles could be performed as effective food-grade stabilizer for Pickering emulsion; however, the sonicated QPI nanoparticles exhibited much better emulsifying and interfacial properties.

Development of food emulsions containing an advanced performance xanthan gum by microfluidization technique.

Gums are often used to increase the viscosity of the continuous phase of oil-in-water emulsions in order to reduce or inhibit some destabilization processes such as creaming. A new type of xanthan gum, advanced performance xanthan gum, which possesses improved rheological properties, has been used as a stabilizer. The addition of advanced performance xanthan gum to egg protein-based emulsions prepared at different homogenization pressures in Microfluidizer was studied. These emulsions showed different droplet size distributions and flocculation degrees. However, all the emulsions studied exhibited the same viscoelastic properties, characterized by a crossover point in the mechanical spectra. This work demonstrates the essential role of this novel gum in the rheology of emulsions. In addition, there is a direct relation between homogenization pressure and flocculation degree. This flocculation led to destabilization by coalescence in these emulsions, being the emulsion processed at the smallest homogenization pressure the most stable.

Fabrication of β-conglycinin-stabilized nanoemulsions via ultrasound process and influence of SDS and PEG 10000 co-emulsifiers on the physicochemical properties of nanoemulsions

Nanoemulsions stabilized by β-conglycinin (7S), β-conglycinin/sodium dodecyl sulfate (SDS) and β-conglycinin/polyethylene glycol 10000 (PEG 10000) were produced via ultrasound process. All the nanoemulsions showed the desired mean particle size and narrow size distribution. The effects of pH, ionic strength and temperature on the properties of the nanoemulsions were investigated, and the long-term stability of the fabricated nanoemulsions was also monitored during storage at 4 °C. The nanoemulsions prepared by 7S exhibited a good stability over various pH (<4 or >5), ionic strength (0–500 mM NaCl), thermal treatment (80 °C) and storage time (0–45 days). The stability of 7S nanoemulsions was enhanced by adding SDS, whereas reduced by adding PEG 10000, which could be attributed to the higher zeta-potential in the present of SDS leading to stronger electrostatic repulsion against droplet flocculation, whereas opposite was observed for the addition of PEG 10000. Therefore, this study provided important evidences for the fabrication of nanoemulsions using protein/surfactant complexes as the emulsion stabilizer via ultrasound process.

Enhancement of physicochemical properties of whey protein-stabilized nanoemulsions by interfacial cross-linking using cinnamaldehyde

The impact of incorporating different levels of cinnamaldehyde (CA) into the oil phase used to prepare whey protein isolate (WPI)-stabilized nanoemulsions was investigated. Stable nanoemulsions could not be formed by pure CA, which was attributed to gravitational separation, but they could be formed from mixtures of CA and triglycerides. The mean particle diameter produced by homogenization decreased with increasing CA, which was attributed to the reduction of oil phase interfacial tension and viscosity. CA enhanced the physical stability of the nanoemulsions to salt addition (0–500 mM) and thermal processing (30–90 °C), but could not prevent droplet flocculation near the protein's isoelectric point (around pH 5). SDS-PAGE and surface load measurements indicated that more protein accumulated at the droplet surfaces in the presence of CA, which was attributed to interfacial crosslinking. CA may therefore be a useful means of modulating the physicochemical properties of protein-stabilized nanoemulsions.

Mechanistic Study of Water Droplet Coalescence and Flocculation in Diluted Bitumen Emulsions with Additives Using Microfluidics

Synthetic crude oils derived from mined oil sands processed via the Clark hot water extraction process do not meet current specifications for pipeline transport and are corrosive to upgrader equipment by virtue of the high residual water content (2–5%) and salts. Formulated chemical additives used in this process can improve the oil quality by accelerating and enhancing the separation of water from oil. The identification and selection of these formulated additives is typically based on performance data collected in field testing for each component or blend. Herein, two methods are reported to study the effect of chemical additives on the phase separation behavior of water in diluted bitumen emulsions prepared in microfluidic devices. First, water droplets in diluted bitumen were created in the presence of chemical additives and the kinetics of droplet coalescence were compared for various additives and concentrations. Second, using a custom-made device geometry, water droplets in diluted bitumen were for...

Formation, stability and in vitro digestibility of nanoemulsions stabilized by high-pressure homogenized lentil proteins isolate

Proteins from pulses such as lentil are seen as an important plant-based alternative to animal proteins in the food and beverage industry. In this research physically modified (homogenized at 5000 psi and 15,000 psi) lentil protein isolate (LPI) solutions (1–2 wt%) were examined as an emulsifier in stabilizing 5 wt% oil-in-water nanoemulsions. High-pressure homogenization was found to significantly decrease LPI particle size distribution, surface hydrophobicity and the interfacial storage moduli relative to the unmodified LPI. However interfacial tension was not affected. No difference in physicochemical properties was observed between the modified LPI solutions prepared at different pressures. All nanoemulsions prepared with modified and unmodified LPI showed droplet flocculation and LPI aggregation, which was increased with protein concentration. Although both the droplet size and instability indices of the modified protein nanoemulsions measured under accelerated gravitation increased after 28 days, they were still better than the unmodified LPI nanoemulsions. In vitro digestion of the nanoemulsions showed significantly higher lipid digestibility for the modified LPI, which was ascribed to the higher interfacial area of smaller droplets and weaker interfacial moduli of modified LPI-stabilized interfaces compared to those with unmodified LPI. Physical modification of LPI by high-pressure homogenization prior to emulsification could be a novel way to utilize pulse proteins in the formation and stabilization of nanoemulsions and improved digestibility under gastrointestinal conditions.

Gel‐like emulsions prepared with zein nanoparticles produced through phase separation from acetic acid solutions

SummaryIn this article, we report the microstructure and rheological property of Pickering emulsions stabilised with zein nanoparticles prepared through phase separation from acetic acid solution. The fresh emulsions showed liquid‐like behaviour and reasonable small droplet size. Interestingly, after 3 days of storage at 25° C, the emulsions changed into solid‐like state. The viscosity remarkably increased, and the storage modulus was much larger than the loss modulus. These results indicate the formation of the gel‐like network in emulsions. The droplet size also showed an obvious increase, while the big droplets could be disrupted into small ones in the presence of sodium dodecyl sulphate. The particle network in the continuous phase was seen in the confocal laser scanning microscopy. Therefore, it is suggested that the gel‐like network is formed by the flocculation of oil droplets and particle network in continuous, mainly through the hydrophobic interactions between the particles.

Effect of extraction condition on properties of pectin from banana peels and its function as fat replacer in salad cream.

Banana peels are wasted from banana processing industry. Pectin is a soluble dietary fibre usually prepared from fruit and vegetable processing wastes. Pectin extraction from banana peels thus should be an effective way of waste utilization. This study aimed to determine the effect of extraction condition on the properties of pectin from peels of Nam Wa banana (Musa (ABB group) 'Kluai Nam Wa') and its role as fat replacer in salad cream. Banana peel pectin (BPP) was extracted with HCl (pH 1.5) and water (pH 6.0) for 30-120min at 90±5°C. Acid extraction yielded 7-11% pectin on a dry basis with galacturonic acid content (GalA), degree of methylation (DM), and viscosity-average molecular weight (Mv) of 42-47, 57-61%, and 17-40kDa, respectively; while water-extracted BPP contained lower DM but higher GalA and Mv. Prolonged extraction raised the pectin yield but lowered the Mv of BPP and the viscosity of their solutions. Incorporation of BPP obtained from 60min acid- and water-extraction into salad cream at 30% oil substitution level resulted in the decreases in viscosity and lightness. All reduced-fat samples were stable to cream separation during 3-weeks storage although the formula containing water-extracted BPP had larger oil droplet size and greater extent of droplet flocculation. There was no difference in sensory scores rated by 50 panelists on thickness, smoothness, and overall acceptability of the full- and reduced-fat salad creams. Therefore, Nam Wa banana peels can be an alternative source of pectin with potential application as fat replacer in food products.

Simulation of phase separation with large component ratio for oil-in-water emulsion in ultrasound field

This paper presents an exploration for separation of oil-in-water and coalescence of oil droplets in ultrasound field via lattice Boltzmann method. Simulations were conducted by the ultrasound traveling and standing waves to enhance oil separation and trap oil droplets. The focus was to the effect of ultrasound irradiation on oil-in-water emulsion properties in the standing wave field, such as oil drop radius, morphology and growth kinetics of phase separation. Ultrasound fields were applied to irradiate the oil-in-water emulsion for getting flocculation of the oil droplets in 420kHz case, and larger dispersed oil droplets and continuous phases in 2MHz and 10MHz cases, respectively. The separated phases started to rise along the direction of sound propagation after several periods. The rising rate of the flocks was significantly greater in ultrasound case than that of oil droplets in the original emulsion, indicating that ultrasound irradiation caused a rapid increase of oil droplet quantity in the progress of the separation. The separation degree was also significantly improved with increasing frequency or irradiation time. The dataset was rearranged for growth kinetics of ultrasonic phase separation in a plot by spherically averaged structure factor and the ratio of oil and emulsion phases. The analyses recovered the two different temporal regimes: the spinodal decomposition and domain growth stages, which further quantified the morphology results. These numerical results provide guidance for setting the optimum condition for the separation of oil-in-water emulsion in the ultrasound field.

Destabilization of Oil-in-Water Emulsions Stabilized by Non-ionic Surfactants: Effect of Particle Hydrophilicity.

We investigate the use of particle hydrophilicity as a tool for emulsion destabilization in Triton-X-100-stabilized hexadecane-in-water emulsions. The hydrophilicity of the particles added to the aqueous phase was found to have a pronounced effect on the stability of the emulsion. Specifically, the addition of hydrophilic fumed silica particles to the aqueous phase resulted in coarsening of the emulsion droplets, with droplet flocculation observed at higher particle concentrations. On the other hand, when partially hydrophobic fumed silica particles were added to the aqueous phase, coarsening of the emulsion droplets was observed at low particle concentrations and phase separation of oil and water was observed at higher particle concentrations. Surface tension and interfacial tension measurements showed significant depletion of the surfactant from the aqueous phase in the presence of the partially hydrophobic particles. The observed changes in the stability of the emulsion and the depletion of the surfactant can be rationalized in terms of changes in the adsorption behavior of the surfactant molecules, from one dominated by hydrogen bonding on hydrophilic particles to one dominated by hydrophobic interactions on partially hydrophobic particles. Our findings also provide, for the first time, an in-depth understanding of antagonistic (destabilizing) effects in mixtures of partially hydrophobic particles and a non-ionic surfactant (Triton X-100) in water.

Impact of short-chain alcohols on the formation and stability of nano-emulsions prepared by the spontaneous emulsification method

The principles of formation and stability of nano-emulsions have been extensively investigated in previous research. In this study, we focus on the impact of short-chain alcohols (C<5) on the formation and stability of oil-in-water nano-emulsions prepared by the spontaneous emulsification method. Due to its smaller droplet size and excellent optical transparency, the nano-emulsion stabilized by Cremophor EL was selected for further study. Addition of alcohol facilitated the nano-emulsion formation, moreover, the droplet size decreased with increasing alcohol chain length (C>2) and hydroxyl groups. Nevertheless, the droplet size then increased further with the addition of alcohols, which we ascribed to the effect of alcohols on droplet flocculation. An optimum Cremophor EL-to-1-butanol ratio of 2:1 was employed to construct the ternary phase diagram. It was found that the fine droplets (r<100nm, PDI<0.2) were obtained only when converting the initial oil drops completely into the lamellar liquid crystalline phase and/or bicontinuous phase and then this phase became supersaturated in oil, so that the nucleation of oil drops occurred spontaneously. According to the dynamic light scattering results, coalescence and Ostwald ripening were the main destabilization mechanisms in our systems. Notably, nano-emulsion stability was greatly improved with ethanol in comparison to 1-propanol and 1-butanol.

Bioaccessibility and antioxidant activity of curcumin after encapsulated by nano and Pickering emulsion based on chitosan-tripolyphosphate nanoparticles

In the current study the influence of different lipid-based formulations (Pickering and nanoemulsions) and their droplet size on curcumin encapsulation and bioaccessibility, as well as on its anti-oxidant activity was investigated. Oil-in-water Pickering emulsion stabilized by chitosan-tripolyphosphate (CS-TPP) nanoparticles and nanoemulsions containing an organic phase (Span80:Tween80), were prepared with either medium chain triglyceride (MCT) or corn oil as long chain triglyceride (LCT). An in vitro gastrointestinal (GIT) model consisting of mouth, gastric and intestinal phases was used to characterize the rate and extent of lipid phase digestion of the ingested samples. A centrifugation method determined fraction of curcumin released into mixed micelles after digestion (bioaccessibility). These findings showed that after subjecting to simulated GIT model, all the emulsion systems experienced a progressive increase in mean particle size, due to droplet flocculation and coalescence after digestion. Electrical charge (ζ) of particles was observed to become highly negative as they passed through GIT due to accumulation of anionic bile salts, phospholipids and free fatty acids at their interfaces. The rate and extent of lipid digestion and bioaccessibility of curcumin increased with decreasing mean droplet diameter (NMCT>NCO>PMCT>PCO). Finally, we showed that as compared to free curcumin, the encapsulated curcumin showed higher radical scavenging activity (RSA), which confirmed the protective effect of the emulsion systems on the antioxidant activity of curcumin.

Improved Low pH Emulsification Properties of Glycated Peanut Protein Isolate by Ultrasound Maillard Reaction.

In this work, peanut protein isolate (PPI) was grafted with maltodextrin (MD) through the ultrasound-assisted Maillard reaction. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed a link between PPI and MD. The substantially increased accessibility of the major subunits (conarachin, acidic subunit of arachin, and basic subunit of arachin) in PPI under high-intensity ultrasound treatment led to changes in the degree of graft (DG), zeta-potential, protein solubility, and surface hydrophobicity of conjugates. Emulsion systems (20% v/v oil, 2.0% w/v PPI equivalent, pH 3.8) formed by untreated PPI, PPI-MDC (PPI-MD conjugates obtained with wet-heating alone), and UPPI-MDC (PPI-MD conjugates obtained with ultrasound-assisted wet heating) were characterized using a light-scatter particle size analyzer and confocal laser scanning microscope. Results showed that emulsions of untreated PPI and PPI-MDC were not stable due to immediate bridging flocculation and coalescence of droplets, whereas that formed by UPPI-MDC with 32.4% DG was stable with a smaller mean droplet size. It was believed that high-intensity ultrasound promoted production of glycated PPI, which was soluble and surface active at pH 3.8 and thus improved emulsification properties for UPPI-MDC. This study shows that glycated PPI by ultrasound-assisted Maillard reaction is an effective emulsifying agent for low pH applications.

Effect of Gum Arabic, Gum Ghatti and Sugar Beet Pectin as Interfacial Layer on Lipid Digestibility in Oil-in-Water Emulsions

The impact of gum arabic (GA), ghatti gum (GG), and sugar beet pectin (SBP) on the digestion rate of emulsified lipids is investigated in vitro under model duodenal digestion condition. The aim was to understand the role of the interfacial layer surrounding the lipid droplets on lipid hydrolysis in order to control lipid digestion. The emulsifier concentration required to provide the same emulsion droplet size decreased in the order: GA > GG > SBP, demonstrating the best emulsifying activity of SBP. The rate and extent of free fatty acid release during lipid digestion did not differ significantly among the three types of gums in emulsions with D[2,3] 2 μm, and the digestive rate decreased in the order: GA > SBP > GG. The difference in digestion rate was attributed to the stability of the emulsified lipid droplets in the stimulated intestinal juice and the resistance of interfacial layer against displacement by bile salts. The difference of resisting against displacement by bile salts for the interfacial layers was detected with bile salts concentration of 0.025 mg/mL, and all of the pre-adsorbed emulsifiers could be completely displaced from interface by bile salts at 5 mg/mL. Emulsions with SBP were susceptible to Ca2+ and Na+ in simulated intestinal juice, resulting in the flocculation and coalescence of emulsion droplets. A reduction of the surface area of lipids would contribute to a slow digestion. Emulsion stabilized by GG was very effective at retarding lipolysis mainly due to the affinity of linked protein moieties of GG and its hydrophobic binding with bile salts. The knowledge gained in the study has important implications in designing proper emulsion-based systems for controlling lipid digestibility at specific sites within the gastrointestinal tract.

Influence of methylcellulose on attributes of β-carotene fortified starch-based filled hydrogels: Optical, rheological, structural, digestibility, and bioaccessibility properties

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.

Production and stabilization of a flaxseed oil multi-layer emulsion containing sodium caseinate and pectin

ABSTRACTThe purpose of this research is the evaluation of a flaxseed oil-in-water emulsion, stabilized by a multi-layer structure consisting of sodium caseinate (Na-caseinate) and pectin to provide a basis for the combination of these materials for future studies. In the first step, the o/w emulsion (10 g oil, 90 g aqueous phase, and a pH 6.8) with varying concentration of Na-caseinate was investigated. Second, the pectin solution (0.05–1.5 g/100 g solution) was added to the primary emulsions and the pH was adjusted to 3.0. The emulsions were characterized by mean particle size (dynamic light scattering and static light scattering techniques), ζ-potential, turbidity value, creaming index, and the visualization of the microstructure. A clear separation of the oil phase at low protein contents and destabilizing by depletion flocculation at high protein content were observed. Extensive droplet flocculation and coalescence were determined until the pectin concentration reached 0.5 g/100 g solution for the secondary emulsion. After 7 days of storage, a 1.5 g/100 g solution pectin content had good stability with a relatively small size distribution, high turbidity value, and no cream phase separation.

Interfacial properties of gelatin from goat skin as influenced by drying methods

Interfacial properties of spray-dried goat skin gelatin (SDGG) and freeze-dried counterpart (FDGG) were determined, in comparison with commercial bovine gelatin (BG). SDGG had the highest surface hydrophobicity (p < 0.05), followed by FDGG and BG, respectively. FDGG became more positively or negatively charged than SDGG at pH below or above pIs (4.83–4.88). Foam expansion and stability of all gelatins increased with increasing concentrations (10–30 g/L) (p < 0.05). SDGG had higher foam expansion and stability than FDGG. Emulsion containing SDGG had the higher droplet size (d32, d43) and flocculation factor than that stabilized by FDGG (p < 0.05). The former also showed the lower stability as indicated by the higher coalescence index with lower negative charge after 10 d of storage. Thus, drying methods affected both foaming and emulsifying properties of goat skin gelatin.