Properties of agents that effectively entrap liquid lipids.

A droplet of an oil-in-water emulsion of methyl linoleate in a saccharide or protein solution that contained with a surfactant, a stabilizer, or both was dehydrated by drying equipment for a single droplet that resembled a spray drier. The lipid exposed on the surface of dehydated samples was extracted and measured by gas chromatography. Gum arabic or gelatin without additives resulted in little lipid being exposed; they were good entrapping agents. Little lipid was exposed with a pullulan solution containing lecithin, sugar ester, carboxymethylcellulose, or sodium caseinate but much was exposed with a maltodextrin solution containing any of the surfactants tested. When both the surfactant lecithin and the stabilizer xanthan gum were added to the emulsion prepared in a maltodextrin solution, lipid was not detected. The results suggested that effective entrapping agents of liquid lipids cause much emulsification, stabilize the emulsion (that is, they cause the continuous phase to be very viscous), and create a dehydrated matrix of fine, dense network layers.     

Development of an optimal formulation for oxidative stability of walnut-beverage emulsions based on gum arabic and xanthan gum using response surface methodology

The susceptibility of lipids to oxidation is one of the most fundamental problems in oil-in-water emulsions. A response surface methodology 5-level-3-factor central-composite rotatable design was applied to study the effects of key formula ingredients including walnut oil (WO, 3-6%, w/w), gum arabic (GA, 5-10%, w/w) and xanthan gum (XG, 0.05-0.15%, w/w) on lipid oxidation in walnut-beverage emulsions. During 30 days’ storage, the oxidation process was monitored by evaluating the peroxide value, anisidine value and total oxidation (Totox) value in different emulsion formulations. Use of XG as a stabilizer at high concentrations considerably inhibited the oxidation of WO in the prepared emulsions. The experimental data were satisfactorily fitted to quadratic models using multiple regression analysis. The optimum conditions to obtain the minimum peroxide (0.923 mequiv. O₂/kg oil), anisidine (0.500) and Totox (2.347) values are met when a walnut-beverage emulsion is formulated with 3% WO, 10% GA and 0.12% XG.     

Preparation of a water-in-oil-in-water (W/O/W) type microcapsules by a single-droplet-drying method and change in encapsulation efficiency of a hydrophilic substance during storage

Microcapsules of a water-in-oil-in-water (W/O/W) emulsion, which contained a hydrophilic substance, 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt (PTSA), in its inner aqueous phase, was prepared by hot-air-drying or freeze-drying the emulsion using a single-droplet-drying method. Pullulan, maltodextrin, or gum arabic was used as a wall material, and the oily phase was tricaprylin, oleic acid, olive oil, or a mixture of tricaprylin and olive oil. An encapsulation efficiency higher than 0.95 was reached except for the microcapsules prepared using gum arabic and oleic acid. The hot-air-dried microcapsules were generally more stable than the freeze-dried microcapsules at 37 degrees C and various relative humidities. The stability was higher for the microcapsules with tricaprylin as the oily phase than for the microcapsules with oleic acid. The higher stability of the microcapsules with tricaprylin would be ascribed to the lower partition coefficient of PTSA to the oily phase. There was a tendency for the stability to be higher at lower relative humidity for both the hot-air- and freeze-dried microcapsules. The volumetric fraction of olive oil in its mixture with tricaprylin did not significantly affect either the encapsulation efficiency or the stability of the hot-air-dried microcapsules.     

Preparation of a Water-in-oil-in-water (W/O/W) Type Microcapsules by a Single-droplet-drying Method and Change in Encapsulation Efficiency of a Hydrophilic Substance during Storage

Microcapsules of a water-in-oil-in-water (W/O/W) emulsion, which contained a hydrophilic substance, 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt (PTSA), in its inner aqueous phase, was prepared by hot-air-drying or freeze-drying the emulsion using a single-droplet-drying method. Pullulan, maltodextrin, or gum arabic was used as a wall material, and the oily phase was tricaprylin, oleic acid, olive oil, or a mixture of tricaprylin and olive oil. An encapsulation efficiency higher than 0.95 was reached except for the microcapsules prepared using gum arabic and oleic acid. The hot-air-dried microcapsules were generally more stable than the freeze-dried microcapsules at 37°C and various relative humidities. The stability was higher for the microcapsules with tricaprylin as the oily phase than for the microcapsules with oleic acid. The higher stability of the microcapsules with tricaprylin would be ascribed to the lower partition coefficient of PTSA to the oily phase. There was a tendency for the stability to be higher at lower relative humidity for both the hot-air- and freeze-dried microcapsules. The volumetric fraction of olive oil in its mixture with tricaprylin did not significantly affect either the encapsulation efficiency or the stability of the hot-air-dried microcapsules.     

Emulsifying behaviour of gum arabic. Part 2: Effect of the gum molecular weight on the emulsion droplet-size distribution

The effect of the molecular weight of the gum arabic sample on droplet-size distributions of n-hexadecane-in-water emulsions (1% wt gum, 10% vol. oil) has been investigated at neutral pH. A high-molecular-weight fraction (0·87% nitrogen) corresponding to 10% of a natural gum (0·38% N) gives initially slightly larger droplets but better emulsion stability than the low-molecular-weight fraction (0·35% N) corresponding to the residual 90% of the original gum. Samples of a different gum arabic (0·35% N) subjected to different degrees of controlled degradation give decreasing emulsion stability with reduction in weight-average molecular weight from 3·1 × 10⁵ to 2·2 × 10⁵Da.     

Rapid exchange of pancreatic lipase between triacylglycerol droplets

Two types of experiments were performed to study the reversibility of interfacial adsorption of pancreatic lipase (PL) to fat droplets during lipolysis. Lipolysis was measured in olive oil/gum arabic emulsions containing radiolabeled triolein in the presence of bile salts and lecithin at rate-limiting concentrations of porcine PL (PPL) or human PL (HPL). The lipolysis rate in a labeled emulsion, i.e. release of [(14)C]oleic acid, was immediately reduced by around 50% upon dilution with an equal amount of an unlabeled emulsion. Further, lipolysis was rapidly and completely suppressed when a non-exchanging lipase inhibitor was present in the second emulsion. These results indicate hopping of lipase between emulsion droplets. Alternative explanations were excluded. Hopping of PL between triolein droplets stabilized with gum arabic at supramicellar bile salt concentrations was observed only in the presence, not in the absence, of lecithin. Displacement from a trioctanoin-water interface of active HPL by an inactive mutant (S152G) was studied in the presence of bile salts by measuring HPL distribution between the water phase and the oil-water interface. Colipase was limiting for HPL binding to the oil-water interface (colipase to lipase molar ratio: 0.5) and, thus, for lipolysis. Upon adding S152G, which has the same affinity for colipase, inactive and active HPL were found to compete for binding at the oil-water interface. When equal amounts of HPL and HPL S152G were used, the lipolysis rate dropped to half the maximum rate recorded with HPL alone, suggesting that half the active HPL was rapidly desorbed from the oil-water interface. Therefore, under various conditions, PL does not remain irreversibly adsorbed to the oil-water interface, but can exchange rapidly between oil droplets, via an equilibrium between soluble and lipid-bound PL.     

Emulsifying behaviour of gum arabic. Part 1: Effect of the nature of the oil phase on the emulsion droplet-size distribution

The influence of the nature of the oil phase on the emulsifying behaviour of gum arabic has been investigated at neutral pH. Time-dependent droplet-size distributions are reported for oil-in-water emulsions (1% wt gum, 10% vol. oil) made with n-hexadecane, -limonene and orange oil. Three different gum samples of known analytical composition have been compared, and it is found that the gum giving the most rapid lowering of the tension at the n-hexadecane-water interface also gives the most stable n-hexadecane-in-water emulsions as well as the smallest droplets with all three oils. On the other hand, the same gum gives the poorest stability of the -limonene-in-water and orange oil-in-water emulsions.     

Oxidation of linoleic acid encapsulated with soluble soybean polysaccharide by spray-drying

Linoleic acid was encapsulated with a soluble soybean polysaccharide, gum arabic, or a mixture of both together with maltodextrin, and the oxidation process of the encapsulated acid was measured at 37 degrees C and at a relative humidity of 12%. The soybean polysaccharide was more effective for encapsulating the acid and suppressing the oxidation of the encapsulated acid than gum arabic. A mixture of the soybean polysaccharide and maltodextrin was also effective for this purpose when the weight fraction of the polysaccharide was equal to or greater than 0.75.     

Stability of cumin oleoresin microencapsulated in different combination of gum arabic, maltodextrin and modified starch

Microencapsulations of cumin oleoresin by spray drying using gum arabic, maltodextrin, and modified starch (HiCap^® 100) and their ternary blends as wall materials were studied for its encapsulation efficiency and stability under storage. The microcapsules were evaluated for the content and stability of volatiles, and total cuminaldehyde, γ-terpinene and p-cymene content for six weeks. Gum arabic offered greater protection than maltodextrin and modified starch, in general, although the order of protection offered was volatiles > cuminaldehyde > p-cymene > γ-terpinene. A 4/6:1/6:1/6 blend of gum arabic/maltodextrin/modified starch offered a protection, better than gum arabic as seen from the t_1/2, i.e. time required for a constituent to reduce to 50% of its initial value. However protective effect of ternary blend was not similar for the all the constituents, and followed an order of volatiles > p-cymene > cuminaldehyde > γ-terpinene.     

Immobilization of inulinase obtained by solid-state fermentation using spray-drying technology

Abstract

This work focuses on the immobilization of a crude inulinase extract obtained by solid-state fermentation using spray-drying technology. Maltodextrin and arabic gum were used as immobilizing agents. The effects of inlet air temperature, maltodextrin/arabic gum ratio and mass fraction of crude enzyme extract on the activity of immobilized inulinase were assessed using a central composite rotatable design (CCRD) (2³). The optimum operational conditions for the immobilization of inulinase by spray-drying was obtained at an inlet air temperature of 200°C, mass fraction of crude enzyme extract of 0.5 wt% and using only arabic gum as immobilizing agent. The immobilized enzyme had good thermostability, comparable with other inulinases obtained from different microorganisms. The method used gave good enzyme activity after immobilization and could be applied to other enzymes which have good thermal stability.     

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. However, considerable difference was observed 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.     

Use of combinations of gum arabic,maltodextrin and soybean protein to microencapsulate ginkgo leaf extracts and its inhibitory effect on skeletal muscle injury

In this study, ethanol extracts of ginkgo leaf were microencapsulated with maltodextrin, gum arabic or a soluble soybean protein by spray-drying. The results indicated that, for the microcapsules, the encapsulation efficiency of 81.3% was achieved when air inlet temperature was 181 °C. The oxidation of ginkgo leaf polyphenol under the conditions was retarded by its microencapsulation with gum arabic, maltodextrin or the soybean protein. Thus, microencapsulation of ethanol extracts of ginkgo leaf significantly improved its oxidative stability. Pharmacological experiment showed that ethanol extracts of ginkgo leaf could enhance ALP activities and collagen I in mouse osteoblast MC3T3-E1 cells. Rabbits pretreated with microcapsules of ethanol extracts of ginkgo leaf significantly inhibited ischemia/reperfusion-induced oxidative injury in rabbits’ skeletal muscle.     

Evaluation of the Stability of Concentrated Emulsions for Lemon Beverages Using Sequential Experimental Designs

The study of the stability of concentrated oil-in-water emulsions is imperative to provide a scientific approach for an important problem in the beverage industry, contributing to abolish the empiricism still present nowadays. The use of these emulsions would directly imply a reduction of transportation costs between production and the sales points, where dilution takes place. The goal of this research was to evaluate the influence of the main components of a lemon emulsion on its stability, aiming to maximize the concentration of oil in the beverage and to correlate its physicochemical characteristics to product stability, allowing an increase of shelf life of the final product. For this purpose, analyses of surface and interface tension, electrokinetic potential, particle size and rheological properties of the emulsions were conducted. A 2^4-1 fractional factorial design was performed with the following variables: lemon oil/water ratio (30% to 50%), starch and Arabic gum concentrations (0% to 30%) and dioctyl sodium sulfosuccinate (0 mg/L to 100 mg/L), including an evaluation of the responses at the central conditions of each variable. Sequentially, a full design was prepared to evaluate the two most influential variables obtained in the first plan, in which concentration of starch and gum ranged from 0% to 20%, while concentration of lemon oil/water ratio was fixed at 50%, without dioctyl sodium sulfosuccinate. Concentrated emulsions with stability superior to 15 days were obtained with either starch or Arabic gum and 50% lemon oil. The most stable formulations presented viscosity over 100 cP and ratio between the surface tension of the emulsion and the mucilage of over 1. These two answers were selected, since they better represent the behavior of emulsions in terms of stability and could be used as tools for an initial selection of the most promising formulations.     

Rheological properties of a double emulsion nutraceutical system incorporating chia essential oil and ascorbic acid stabilized by carbohydrate polymer-protein blends

Four water-in-oil-in water (W₁/O/W₂) double emulsions were made by adding the primary emulsion (W₁/O) containing 74% (w/w) of chia essential oil, 6% (w/w) of ascorbic acid, and a 0.2 dispersed phase mass fraction (φW₁/O) to aqueous solutions (W₂) of mesquite gum (MG), maltodextrin DE-10 (MD) and whey protein concentrate (WPC) in different proportions (MG66-MD17-WPC17 and MG17-MD66-WPC17), and in a ratio of 1:2.12 and 1:4.12 W₁/O to dry biopolymers blends solids. All the double emulsions showed type C morphologies and only slight changes in the volume-weighted mean diameter (d_4,3) throughout the storage time, indicative of good stability, despite they presented bimodal size distributions, but the double emulsion formulated with a predominant proportion of MD and ratio 1:2.12 provided a higher stability against droplet coalescence. All the double emulsions displayed viscoelastic character dependent on frequency.     

Effect of polymeric cosolutes on calcium pectinate gelation. Part 3. Gum arabic and overview

Addition of gum arabic (average M_r≈450 kDa; 0.5–2.0 wt%) to solutions of low methoxy pectin (DE 31; 2.0 wt%; pH≈2.9–3.0) with stoichiometric Ca²⁺ caused massive increases in G′ and G″ in the pre-gel state at 90 °C (attributed to segregative interactions promoting formation of calcium-mediated ‘egg-box’ junctions between pectin chains) but had little effect on the gels formed on cooling to 5 °C. This is in marked contrast to the behaviour of other polymeric cosolutes studied in the investigations reported in the two preceding papers, which caused large reductions in gel moduli (attributed to excessive association of calcium pectinate into large aggregated bundles); the difference is tentatively ascribed to strengthening of the calcium pectinate network by divalent counterions to the uronate residues in gum arabic. When the complication of cation exchange was eliminated by extensive dialysis of gum arabic against 100 mM Na⁺ and use of the final dialysate in preparation of mixtures with calcium pectinate, massive increases in G′ and G″ at high temperature were again observed, but with accompanying reductions in moduli at low temperature, which, at gum arabic concentrations above 1.0 wt%, arose from collapse of the developing calcium pectinate network during cooling. The tentative conclusion from this work, and from the two preceding papers, is that enthalpically unfavourable (segregative) interactions between low methoxy pectin and polymeric cosolutes can be relieved in two ways: (i) Ca²⁺-mediated self-association of pectin into compact ordered assemblies which occupy less of the total volume, and (ii) conformational rearrangement of the cosolute molecules to minimise segmental interactions with pectin; conformational rearrangement is inhibited by chain stiffness and by branching; thus polymeric cosolute molecules of limited flexibility are more effective in promoting self-association of pectin than more flexible molecules of comparable size, and branched molecules are more effective than linear chains of comparable stiffness.     

Emulsifying properties of a marine bacterial exopolysaccharide

Exopolysaccharide produced by a marine Enterobacter cloaceae (designated as EPS 71a) emulsified hexane, benzene, xylene, kerosene, paraffin oil, cottonseed oil, coconut oil, jojoba oil, castor oil, groundnut oil and sunflower oil. However, it could form stable emulsions with groundnut oil and hexane at optimal concentration of 1 mg ml⁻¹. Further increase in concentration of EPS 71a did not show noteworthy increase in emulsification indices. Emulsions with groundnut oil and hexane were stable up to 10 days between pH 2 and 10 and in the presence of sodium chloride in the range of 5–50 mg ml⁻¹ at 35–37 °C. EPS 71a formed stable emulsion with xylene as compared to commercial gums such as arabic, tragacanth, karaya and xanthan.     

Release characteristics of flavor from spray-dried powder in boiling water and during rice cooking

The release characteristics of flavor in boiling water and the flavor retention in the rice after cooking were investigated by using spray dried powder in encapsulated in or emulsified with d-limonene or ethyl n-hexanoate in cyclodextrin and maltodextrin, or in gum arabic and maltodextrin. The behavior of flavor release into the boiling water was well simulated by Avrami's equation. The retention of d-limonene and ethyl n-hexanoate in cooked rice was correlated in each case with the flavor amount of spray-dried powder added.     

Impact of Lipase, Bile Salts, and Polysaccharides on Properties and Digestibility of Tuna Oil Multilayer Emulsions Stabilized by Lecithin–Chitosan

The influence of lipase, bile salts, and polysaccharides (pectin and maltodextrin) on the properties and digestibility of lecithin/chitosan-stabilized tuna oil-in-water multilayer emulsions were studied when they were subjected to an in vitro digestion model. All emulsions became unstable to creaming after passing through the digestion model, as deduced from the formation of large visible brown clumps on the top of the emulsions. The release of free fatty acids and glucosamine from the emulsions suggested that lecithin/chitosan-coated droplets were degraded by lipase under simulated gastrointestinal conditions. The amount of free fatty acids released per unit amount of emulsion was higher when bile salt was included in the digestion model or anionic polysaccharide (pectin) was present in the emulsions. These results have important implications for the utilization of multilayered emulsions for the encapsulation, protection, and delivery of n-3 fatty acids and other bioactive lipids.     

Storage of Yarrowia lipolytica lipase after spray-drying in the presence of additives

Lipase from Yarrowia lipolytica is an enzyme that presents numerous potentialities for biotechnological applications. This work describes the development of powders obtained by atomization of supernatants lipase from Y. lipolytica LGx6481. Two formulations were studied: one formulation with skim milk powder and gum arabic, and the other with maltodextrin, calcium chloride and gum arabic. After drying, powders were stored at 4 and 20 °C in aluminium hermetic bags to evaluate their stability over a period of one year. The influence of water activity and glass transition temperature (T_g) on the powder's storage were also studied.     

Emulsification using environmental compatible emulsifiers and de-emulsification using D.C. field and immobilized Nocardia amarae

As environmental compatible emulsifiers, various polysaccharides were investigated and de-emulsification methods were studied using filtration, direct current (D.C.) field, and also Nocardia amarae. 0.01% (v/v) of alginic acid, arabic gum, chitosan, and curdlan showed more than about 2 h of emulsion stability in the half-life of emulsion layer by a homogenizer and showed about twice synergic effects with other polysaccharides in emulsification activity at the ratio of 9:1 (v/v). De-emulsification by 110V D.C. field took about 1 h for the separation of oils from 1 l of oil-in-water emulsion in case of 0.01% arabic gum. Oil-water separator was designed using non-woven fabrics in filtration system and Nocardia amarae grown in n-hexadecane or kerosene was immobilized in the non-woven fabrics.