Cream Layer Research Articles

Mixtures of Quillaja saponin and beta-lactoglobulin at the oil/water-interface: Adsorption, interfacial rheology and emulsion properties

Aim of the present study was to investigate the interfacial properties of mixed films of Quillaja saponins (QS) and beta-lactoglobulin (β-LG) at the oil/water-interface. It was hypothesized that due to the differences in the physical characteristics of the dispersed phase molecular interactions and film characteristics at the oil/water interface substantially differ from the air/water-interface. Furthermore QS/β-LG-interactions will affect stability of emulsions in a concentration-dependent manner. Oscillating drop experiments were performed with subsequent analysis of raw data (Lissajous-plots) to discover non-linear behavior upon compression and expansion. Interfacial shear rheology as well as dynamic interfacial tension and two-fluid needle experiments were performed to comprehensively characterize interfacial properties of mixtures of QS/β-LG. Finally, emulsions were prepared and their stability, oil droplet size and ζ-potential were determined. It became obvious that QS dominates the interfacial film in a binary mixture as indicated by dynamic interfacial tension and dilational rheology. Strain stiffening was observed for mixed QS/β-LG interfacial layers upon dilational expansion at an amplitude above 2.8%. Intermolecular interactions increased in mixtures of QS/β-LG as indicated by shear rheology. Emulsion experiments showed extensive aggregation of oil droplets in QS/β-LG-emulsions with high content of β-LG. Aggregation of oil droplets increased velocity of creaming and after 7days a distinct creaming layer was visible. Changes in dispersity were influenced by concentration and ratio of QS and β-LG.

Phase behaviour and droplet size of oil-in-water Pickering emulsions stabilised with plant-derived nanocellulosic materials

The preparation, stability and phase behaviour of oil-in-water emulsions formed by dodecane and water and stabilised by naturally amphiphilic, chemically unmodified cellulose nanofibrils (CNF), TEMPO-oxidized cellulose nanofibrils (T-CNF) and cellulose nanocrystals (CNC) were investigated. The stability towards prolonged storage, high temperature (maximum 85°C), shear and dilution with water was evaluated. Droplet size distributions were determined from micrographs and by NMR diffusion measurements. Oil-in-water Pickering emulsions were formed at all stabiliser and O/W ratios (20–35% oil, 0.1–1.5% nanocellulose) for all three nanocellulosic materials, without the use of any additives. All emulsions creamed rapidly; the creaming layers remained stable for at least one month. The volume of creaming layers formed by CNF and T-CNF are larger and the stability towards coalescence, low shear and high temperature of CNF and T-CNF are higher than the corresponding properties of emulsions stabilised with CNC. This is probably due to the networks formed by the longer fibrils. T-CNF forms a dilute stable emulsion in equilibrium with the creaming layer. No emulsion droplets were visible in the water phases in equilibrium with the creaming layers formed by emulsions stabilised by CNC or CNF. The stability of the dilute T-CNF emulsions is probably due to the ionic charge of the nanofibrils, which is higher than that of the CNF or CNC. It seems that nanocellulosic materials primarily act as stabilisers against coalescence rather than flocculation.

Short communication: Improved method for centrifugal recovery of bacteria from raw milk applied to sensitive real-time quantitative PCR detection of Salmonella spp.

Centrifugation is widely used to isolate and concentrate bacteria from dairy products before assay. We found that more than 98% of common pathogenic bacteria added to pasteurized, homogenized, or pasteurized homogenized milk were recovered in the pellet after centrifugation, whereas less than 7% were recovered from raw milk. The remaining bacteria partitioned into the cream layer of raw milk within 5 min, and half-saturation of the cream layer required a bacterial load of approximately 5×108 cfu/mL. Known treatments (e.g., heat, enzymes or solvents) can disrupt cream layer binding and improve recovery from raw milk, but can also damage bacteria and compromise detection. We developed a simple, rapid agitation treatment that disrupted bacteria binding to the cream layer and provided more than 95% recovery without affecting bacteria viability. Combining this simple agitation treatment with a previously developed real-time quantitative PCR assay allowed the detection of Salmonella spp. in raw milk at 4 cfu/mL within 3 h. To our knowledge, this is the first report of an effective method for achieving high centrifugal recovery of bacteria from raw milk without impairing bacterial viability.

Process optimization for in-line production of <italic>Rabri</italic>

Scraped surface heat exchanger (SSHE) was integrated with conical process vat (CPV) for in-line production of <italic>rabri</italic>. Response surface methodology was applied to optimize the process parameters on the basis of sensory score, chromatic and textural attributes. The four factors considered for optimization were initial concentration of milk in SSHE, final concentration of milk in CPV, ratio of clotted cream layer (CCL) to sweetened concentrated milk (SCM) and steam pressure of CPV during removal of CCL. Optimum parameters predicted for <italic>rabri</italic> production were initial concentration of milk to 30% total solids (TS) in SSHE, final concentration of milk to 40% TS in CPV before sugar addition, 0.167 CCL/SCM ratio and 0.8 kg/cm<sup>2</sup> steam pressure of CPV during removal of CCL. The observed values for flavour, body and texture, colour and appearance, overall acceptability, firmness, L*, a* and b* were 7.97, 7.93, 8.23, 8.067, 0.3540, 75.907, 01.14 and 16.3197 respectively.

Avoiding skin creams right before radiation: Myth or sound advice?

51 Background: Radiation dermatitis in breast cancer patients is common and often treated with topical creams. Patients are traditionally advised to avoid lotions for several hours before radiotherapy (RT) based on concern that creams might increase skin dose. With modern RT’s improved skin sparing, this recommendation may be irrelevant. We hypothesize that applying either metallic or non-metallic creams before treatment would have minimal effect on skin dose. Methods: We conducted an online, 24-question OncoLink survey of patients and providers to determine current skin cream practices. To evaluate the dosimetric effect of creams, we delivered 200 MU at 100 cm SSD and measured the dose at the surface and 2 cm depth in a tissue equivalent phantom, with or w/o 2 common skin creams, Aquaphor and silver sulfadiazine. We assessed the effect of various photon and electron energies, cream thicknesses and beam incidence on dose. The effect of creams on skin dose was also evaluated in C57BL/6 mice using γ-H2AX IHC staining. Results: 27 of 33 surveyed breast cancer patients (82%) and 43 of 45 providers (96%) either received or gave the advice to avoid applying creams prior to RT treatments. Measurements showed no difference in dose at the surface or 2 cm depth with or w/o a 1-2 mm application of either cream when using enface 6 or 15 MV photons. The same application of cream had no effect on surface dose as a function of beam incident angle from 15-60°, except for a 7% increase at 60° with the silver cream. Surface dose for 6 & 15 MV beams were significantly increased with a thicker (≥3 mm) layer of cream. For 6 MV, the surface dose was 105 cGy (Aquaphor), 102 cGy (silver cream) and 88 cGy (controls). For 15 MV, the doses were 70, 60 and 52 cGy. With 6 and 9 MeV electrons, there was only a 2-5% increase in surface dose with use of creams. There were no dose differences at 2 cm depth. Irradiated skin in mice showed no difference in γ-H2AX positive foci with or w/o creams. Conclusions: This is the first dosimetric assessment of the effect of skin creams for RT dermatitis. Our findings suggest that thin or moderately applied creams, even if applied just prior to RT, have minimal impact on skin dose, regardless of beam energy or beam incidence. Applying very thick amounts of cream just prior to RT increased surface dose and should be avoided.

A Raman spectroscopic study of meat protein/lipid interactions at protein/oil or protein/fat interfaces

SummaryStructural changes in proteins of meat, FC (fat cream layers) and OC (soya bean oil cream layers) were studied by Raman spectroscopy. Results revealed that adsorption of proteins to the cream layers resulted in a maximum scattering change from 1657 to 1661 cm−1, the intensity of amide I was significantly increased (P < 0.05), the percentages of secondary structures of proteins in the raw meat and meat cream layers were significantly different (P < 0.05), the bands near 540 and 475 cm−1 were significantly (P < 0.05) higher in intensities in the soya bean oil cream layer samples compared to raw meat alone, the normalised intensity of the tryptophan band near 758 cm−1, from 0.52 in the raw meat to 1.11 (fat cream layer) or 0.72 (soya bean oil cream layer). These results indicated that disulphide bonds, hydrophobic interactions and hydrogen bonding were of the main interactions observed in proteins and lipids at the emulsion interface.

Characterizing the structural and surface properties of proteins isolated before and after enzymatic demulsification of the aqueous extract emulsion of peanut seeds

We isolated and characterized various proteins (adsorbed and unadsorbed) from the aqueous extract emulsion of peanut seeds. The peanut emulsion was further subjected to a freeze-thaw treatment or enzymatic hydrolysis by the alkaline endopeptidase Mifong®2709. The proteins in the residual cream layer and the aqueous phase, obtained from the freeze-thaw treatment as well as the cream layer peptides and aqueous phase peptides obtained at various periods of hydrolysis (namely 5, 10, 30, and 60 min), were isolated and analyzed for structural (molecular weight, disulfide bond content, and surface hydrophobicity) and surface (dynamic interfacial tension, emulsifying activity, and stability indices) properties. The peanut proteins adsorbed at the oil-water interface showed superior emulsification properties and unique structural characteristics consisting of large molecular weight proteins and small molecular weight oleosins, and also possessed a higher disulfide bond content and greater surface hydrophobicity. The proteins in the residual cream layer derived from the freeze-thaw treatment had a higher disulfide bond content, surface hydrophobicity, and emulsification indices than the proteins in the aqueous phase. In contrast, following the hydrolysis of the emulsion, the resulting cream layer peptides and the aqueous phase peptides exhibited a significantly lower disulfide bond content, weaker surface hydrophobicity and lower emulsification indices than the intact proteins. These protein structural changes following hydrolysis contributed to the destabilization of the peanut emulsions. We also observed a positive correlation for the disulfide bond content and the surface hydrophobicity with the emulsifying activity index (EAI), R2 = 0.963 and 0.982, respectively as well as the emulsion stability index (ESI), R2 = 0.920 and 0.906, respectively.

Physicochemical and acid gelation properties of commercial UHT-treated plant-based milk substitutes and lactose free bovine milk

Physicochemical and acid gelation properties of UHT-treated commercial soy, oat, quinoa, rice and lactose-free bovine milks were studied. The separation profiles were determined using a LUMiSizer dispersion analyser. Soy, rice and quinoa milks formed both cream and sediment layers, while oat milk sedimented but did not cream. Bovine milk was very stable to separation while all plant milks separated at varying rates; rice and oat milks being the most unstable products. Particle sizes in plant-based milk substitutes, expressed as volume mean diameters (d4.3), ranged from 0.55μm (soy) to 2.08μm (quinoa) while the average size in bovine milk was 0.52μm. Particles of plant-based milk substitutes were significantly more polydisperse compared to those of bovine milk. Upon acidification with glucono-δ-lactone (GDL), bovine, soy and quinoa milks formed structured gels with maximum storage moduli of 262, 187 and 105Pa, respectively while oat and rice milks did not gel. In addition to soy products currently on the market, quinoa may have potential in dairy-type food applications.

Multilayer emulsions as a strategy for linseed oil microencapsulation: Effect of pH and alginate concentration

The influence of pH (4–7) and sodium alginate (SA) concentration (0.125–0.25 wt%) on the properties of linseed oil-in-water emulsions stabilized by a whey protein isolate (WPI) was investigated. Droplet size, droplet charge, creaming stability and optical microscopy measurements as well as determination of non-adsorbed biopolymers at the oil–water interface were made. At pH 6 and 7, anionic alginate did not adsorb onto the surfaces of WPI-coated droplets due to strong electrostatic repulsion between biopolymers. Remaining SA molecules in the continuous phase induce emulsion destabilization by depletion flocculation, with the formation of floc chains that, after a period of latency, promoted phase separation with high creaming indexes. Both the delay time and the cream layer thickness increased when increasing SA concentration. At pH 5, ζ-potential measurements demonstrate deposition of SA onto WPI interfacial membrane to form a bilayer around oil droplets. Besides, no droplet aggregation was observed and emulsions were stable to creaming after one-week storage. At pH 4, 0.125 wt% SA emulsions were prone to extensive droplet aggregation probably enhanced by bridging flocculation, exhibiting a gel-like microstructure of interconnected flocs, which then promoted phase separation. However, when increasing initial SA concentration in these systems, the degree of droplet aggregation decreased. These results suggest that the best conditions to produce stable emulsions as encapsulation matrices for the delivery of high polyunsaturated fatty acid oils would be 0.25 wt% SA pH 5.

Influence of the plate-type continuous micro-separator dimensions on the efficiency of demulsification of oil-in-water emulsion

The objective of this article is to find the optimal dimensions of rectangular plate-type micro-separators in order to enhance the continuous separation of immiscible liquids. The main structure of the separators contains two plates: a hydrophobic (PTFE) upper plate and a hydrophilic (stainless steel) bottom plate which formed the contact surfaces for the fluids in the channel. The devices have two outlets, one for the aqueous phase and the other for the organic phase enabling the continuous separation and withdrawal of the separated phases. Demulsification has been carried out using Shellsol/water emulsion in the presence of a non-ionic surfactant (Tween 80). The separation efficiency is investigated as a function of micro-separator sizes, channel depths, flow rates and plate configurations. The major parameter that controls the destabilization mechanism is the ratio between the droplet size and the channel depth. When the size of the dispersed droplets remains smaller than the height of the separator (channel depths: 25–100μm), creaming is the main demulsification mechanism. Creaming refers to the migration of the dispersed phase of an emulsion, under the influence of buoyancy. The particles float upwards and rise to the top due to the difference in the densities of the particles and the medium. The separation efficiency depends mainly on the residence time of the liquid/liquid mixture in the device regardless of the separator dimensions and channel heights. The separation rate is limited by the removal of the cream layer, formed at the top of the upper plate, from the separator. When the size of the dispersed droplets is larger than the depth of the separator (channel height of 9μm), the separation performance and mechanism become different. The coalescence of the dispersed droplets occurs by passing through the device. The comparison of the data corresponding to creaming and coalescence phenomena emphasizes that the coalescence greatly enhance and accelerate the separation action. The phase separation in the micro-coalescer takes place considerably faster than in the micro-separators.

Stabilization of water in oil in water (W/O/W) emulsion using whey protein isolate-conjugated durian seed gum: Enhancement of interfacial activity through conjugation process

The present work was conducted to investigate the effect of purification and conjugation processes on functional properties of durian seed gum (DSG) used for stabilization of water in oil in water (W/O/W) emulsion. Whey protein isolate (WPI) was conjugated to durian seed gum through the covalent linkage. In order to prepare WPI–DSG conjugate, covalent linkage of whey protein isolate to durian seed gum was obtained by Maillard reaction induced by heating at 60°C and 80% (±1%) relative humidity. SDS-polyacrylamide gel electrophoresis was used to test the formation of the covalent linkage between whey protein isolate and durian seed gum after conjugation process. In this study, W/O/W stabilized by WPI-conjugated DSG A showed the highest interface activity and lowest creaming layer among all prepared emulsions. This indicated that the partial conjugation of WPI to DSG significantly improved its functional characteristics in W/O/W emulsion. The addition of WPI-conjugated DSG to W/O/W emulsion increased the viscosity more than non-conjugated durian seed gum (or control). This might be due to possible increment of the molecular weight after linking the protein fraction to the structure of durian seed gum through the conjugation process.

Comfrey root extract in combination with methylnicotinate in the treatment of acute upper or lower back pain: Results of a double-blind, placebo-controlled, multicenter, three-arm RCT

Several RCTs have confirmed the efficacy of comfrey root extract (Symphytum officinale L.) (CRE) in painful muscle and joint complaints. The topical pharmacotherapeutic approach has also included hyperaemising drugs to relax the contracted muscle area. Thus, the extract has also been used in combination with methylnicotinate (MN). The objective was to show the superiority of a CRE plus MN cream (Kytta-Balsam® f) to MN and placebo cream in patients with acute upper or low back pain. In this RCT 379 patients were assigned to three groups (combination of 35% CRE plus 1.2% MN, n = 163; MN, n = 164; placebo, n = 52) and applied a 12 cm layer of cream 3 times daily for 5 days. The trial included four visits. The primary efficacy variable was the AUC (area under the curve) of the VAS (Visual Analogue Scale) on active standardised movement values at visits 1 to 4. Patients performed standardised, muscle group specific tests. Secondary measures included back pain at rest, pressure algometry, consumption of analgesic medication, functional impairment measured with Oswestry Disability Index, and global assessment of response. The AUC of the VAS on active standardised movement was markedly smaller in the combination treatment group than in the MN and the placebo group (ANOVA: p < 0.0001). The pairwise comparisons of the mean AUCs of VAS sums showed values 27% lower in favour of the combination compared to MN, and values 50% lower in favour of the combination compared to placebo. MN alone reached a reduction in this variable of 31% compared to placebo. All pairwise comparisons were statistically significant (t-test: p < 0.0001). The results were consistent across the primary and all secondary variables. Patients treated with the combination had significant superior reductions in pain scores and were more satisfied with the treatment effect. The combination demonstrated superiority to the two other treatment arms, while methyl nicotinate displayed a considerable effect as well.

Interaction between Whole Buttermilk and Resveratrol

The interaction between buttermilk and resveratrol (trans-3,5,4'-trihydroxystilbene) was examined using fluorescence spectroscopy. Ultracentrifugation of buttermilk (10% total solids, TS)-resveratrol (100-1600 μM) mixtures yielded three fractions comprising cream (14.79% w/w, 1.12% TS), milk serum (75.94% w/w, 5.56% TS), and a casein-rich precipitate (9.27% w/w, 2.94% TS). The majority of the added resveratrol was partitioned into the casein-rich precipitate (50.5-56.8%), with lesser amounts in the milk serum (35.3-41.2%) and cream layer (7.9-8.7%), demonstrating that most of the resveratrol interacted with the proteins. The interaction of the milk proteins with resveratrol was investigated by measuring the quenching of protein intrinsic fluorescence. Complex formation was spontaneous and exothermic. The apparent binding constants between milk proteins in buttermilk and resveratrol were ≥ 2.47 × 10(4), 1.65 × 10(4), 1.11 × 10(4), and 0.72 × 10(4) M(-1), respectively, at 278, 288, 298, and 308 K. The increased aqueous solubility of resveratrol by complexation to whole buttermilk makes it useful as a food vehicle for carrying resveratrol.

The influence of carrageenan on interfacial properties and short-term stability of milk whey proteins emulsions

In this work the effects of ι-carrageenan and κ-carrageenan on macroscopic properties of commercial sunflower oil/water systems, stabilised by whey proteins, were investigated by measuring the interfacial and bulk rheological properties, the particle size distribution and the creaming stability. The main aim was to investigate the relationship between interfacial characteristics and emulsion stability, evidencing the conditions to be used to improve the emulsion properties.Transient interfacial tension and dilatational dynamic moduli were measured with a “pendant drop” tensiometer; experimental results have shown that, in the investigated range, the carrageenan increases the interfacial tension and yields a more resistant layer surrounding the oil drops, mostly in the presence of ι-type.Bulk rheological tests carried out on emulsions, manufactured by using the same components and sunflower oil, have evidenced that the addition of the carrageenan to the protein system causes an increase of the emulsion viscosity and, as a consequence, a reduction of droplet movement and aggregation.The analysis of Drop Size Distribution (DSD), adopted to investigate the coalescence stability, evidenced that polysaccharide addition yields larger droplets but reduces significantly the change of polydispersity with time (within the tested range), suggesting greater emulsion stability. This result was also confirmed by an analysis of the “creaming index”, carried out measuring the separated cream layer of samples stored up to 24 h: low values were obtained when carrageenan was used. Moreover, it was observed that stability improves significantly by adding ι-carrageenan rather than κ-carrageenan.Finally, experimental results have shown that DSD seems more affected by interfacial tension values, whereas stability is dependent on the viscoelasticity of the interfacial layer.

Lipid Digestion of Protein Stabilized Emulsions Investigated in a Dynamic In Vitro Gastro-Intestinal Model System

This study investigated the effect of gastric passage of protein stabilized emulsions, i.e., whey protein isolate (WPI) and lysozyme, under dynamic in vitro conditions on both the gastric and intestinal lipolysis. Emulsions were prepared at neutral pH to enable an opposite surface charge. Experiments were performed in a multi-compartmental digestion model (TNO Gastro-Intestinal Model) including a gastric compartment simulating in vivo conditions, i.e., gradual acidification, mixing, lipolysis and proteolysis. Under gastric conditions, lysozyme-stabilized emulsions remained macroscopically homogenous, whereas WPI-stabilized emulsions separated into a cream and serum layer. Microscopy revealed flocculation of both emulsions, but larger particles were found for the initial negatively charged WPI-stabilized emulsions compared to the positively charged lysozyme-stabilized emulsions. This suggested that creaming was due to larger flocs formation caused by a change from net negative to net neutral charge as an effect of the gradual decreasing pH. Analysis of lipid composition, i.e., free fatty acids (FFA), monoglycerides, diglycerides (DG) and triglycerides revealed mainly FFA and DG in the gastric compartment. As a result of creaming, the entry of lipids into the small intestinal part was delayed for WPI-stabilized emulsions. However, the total amount of FFA released at the end of the experiment was similar for both emulsions. Our results show, that the charge differences affected the creaming behavior, but not the lipase activity, on the two studied emulsions.

Preparation and characterization of Mentha × piperita oil emulsion for housefly (Musca domestica L.) control

Emulsified concentrate (EC) formulation of Mentha×piperita oil was prepared by taking (w/w) 40% oil, 45% aeromax, 3% butanol-1 and 12% surfactant (CABS-70 and NP-20 in variable ratio). Three ECs (designated as A, B and C) were screened amongst prepared ECs on the basis of physical criteria. Emulsions were assessed for their stability through creaming volume, particle size and zeta potential determination. Particle size of emulsions varied between 536.7 and 1133.6nm, while zeta potential value (−45.9 to −47.3mV) was strongly negative suggesting stability. Characterization of emulsion for its pH (≈6.6–7.5) and flash point analysis (≈90–92°C) indicated a stable formulation, which was safe to handle and transport. Prepared emulsions were stable at various temperatures (4–60°C), and showed a thin creaming layer at the upper surface without any phase separation, when subjected to centrifugation. Freeze/thaw cycles showed no visible change in appearance in EC ‘A’ and ‘B’, while EC ‘C’ showed tendency to rupture, i.e. dispersion of oil droplets in emulsion, after 6 cycles. Bioefficacy of EC ‘B’, adjudged as most stable emulsion, against adults of housefly (Musca domestica) showed 70–88% repellency with freshly prepared EC. The repellency decreased to 34–72% after 12 months storage at room temperature. Assay against housefly larvae showed an LC50 value of 0.08μL/cm2 (emulsion from freshly prepared EC) and 0.34μL/cm2 (emulsion from stored EC).

Creaming enhancement in a liter scale ultrasonic reactor at selected transducer configurations and frequencies

Recent research has shown that high frequency ultrasound (0.4–3MHz), can enhance milkfat separation in small scale systems able to treat only a few milliliters of sample. In this work, the effect of ultrasonic standing waves on milkfat creaming was studied in a 6L reactor and the influence of different frequencies and transducer configurations in direct contact with the fluid was investigated. A recombined coarse milk emulsion with fat globules stained with oil-red-O dye was selected for the separation trials. Runs were performed with one or two transducers placed in vertical (parallel or perpendicular) and horizontal positions (at the reactor base) at 0.4, 1 and/or 2MHz (specific energy 8.5±0.6kJ/kg per transducer). Creaming behavior was assessed by measuring the thickness of the separated cream layer. Other methods supporting this assessment included the measurement of fat content, backscattering, particle size distribution, and microscopy of samples taken at the bottom and top of the reactor. Most efficient creaming was found after treatment at 0.4MHz in single and double vertical transducer configurations. Among these configurations, a higher separation rate was obtained when sonicating at 0.4MHz in a vertical perpendicular double transducer setup. The horizontal transducer configuration promoted creaming at 2MHz only. Fat globule size increase was observed when creaming occurred. This research highlights the potential for enhanced separation of milkfat in larger scale systems from selected transducer configurations in contact with a dairy emulsion, or emulsion splitting in general.

Microencapsulation of oil droplets using freezing-induced gelatin–acacia complex coacervation

A freezing process was applied to control the kinetics of a gelatin–acacia complex coacervation technique for encapsulating emulsified oil droplets. An oil-in-water emulsion was stabilized with a gelatin–acacia solution, and the pH of the solution was adjusted to a selected value with acetic acid. When the pH of the emulsion was adjusted to 4.7, the system was visibly stable at ambient temperature for up to 12h. Freezing the emulsion caused polymer phase separation (complex coacervation) in the cryoconcentrated phase and resulted in encapsulated oil droplets and the accumulation of a cream layer in the freeze-thawed solution. Observation by transmission electron microscopy clarified the formation of 50–4000nm core–shell nano-microparticles, the surfaces of which were surrounded by polymeric membranes. The membrane properties of the particulate systems were dependent on the cooling rate that was used during freezing. For example, when an emulsion with a pH of 4.7 was frozen, a cooling rate of −1.0°C/min maximized the encapsulation yield, whereas a rate of −2.0°C/min was effective in limiting the release rate of the ingredient (β-carotene) from the oil phase through the shell membrane. The results of this study suggest that the formation of nano-microparticles could be highly associated with the kinetics of freezing, so their resultant properties could be fine-tuned using a freezing operation. This is a potential concept providing a novel strategy for engineering core–shell nanoparticles.

Extraction, isolation and characterisation of oil bodies from pumpkin seeds for therapeutic use

Pumpkin, a member of the Cucurbitaceae family has been used frequently as functional medicines for therapeutic use. Several phytochemicals such as polysaccharides, phenolic glycosides, 13-hydroxy-9Z, 11E-octadecatrienoic acid from the leaves of pumpkin, proteins from germinated seeds, have been isolated. Here the influence of pH, ionic strength, and temperature on the properties and stability of oil bodies from pumpkin (Cucurbita) were determined with a view to patterning oil body size and structure for future therapeutic intervention. Oil bodies from pumpkin seeds were extracted, isolated, characterised using optical microscopy, zeta potential and particle size distribution obtained. During microscopic analysis, the oil bodies were more intact and in an integrated form at the time of extraction but were ruptured with time. Water extracted oil bodies were spherical for all four layers where cream had larger oil bodies then upper curd. Lower curd and supernatant had considerably smaller size with lower curd densely packed and seemed to be rich in oil bodies than any of the four layers. At pH 3, in the absence of salt, the zeta potential is approximately +30 mV, but as the salt concentration increases, the ζ potential rises at 10 mM but then decreases over the salt range. This trend continues for the upper curd, lower curd and the supernatant and the degree of the reduction (mV) in zeta potential is of the order cream<upper curd<lower curd<supernatant. At pH 7.4, physiological pH, the changes in salt concentration from 10 to 100 mM reduce the zeta potential significantly across all layers such that increased salt concentrations induce negative potentials. Increasing the salt concentrations still further, however, does not make the ζ potential more negative. However, at pH 9 the zeta potential falls from 0 to -50 mV as the salt concentration increases with the largest reduction shown with 100 mM salt. Particle size distribution at increasing pH salt concentration shows the average size distribution of pumpkin seed oil bodies at an increasing pH (3, 7.4 and 9) and salt concentration (0, 10, 50 and 100 mM) across all four layers. The lowest average size distributions are seen at pH 7.4 across all four layers especially within the cream and upper curd layers. At pH 3 and 9, the highest average size distributions are seen in the lower curd and cream layers. Oil bodies can be extracted, isolated and from pumpkins using an aqueous extraction method and may prove to be a useful new source of lipids for application in patterning therapeutics for clinical use.

Vaginal distribution and retention of a multiparticulate drug delivery system, assessed by gamma scintigraphy and magnetic resonance imaging

BackgroundFor any new vaginal dosage form, the distribution and retention in the vagina has to be assessed by in vivo evaluation. We evaluated the vaginal distribution and retention of starch-based pellets in sheep as live animal model by gamma scintigraphy (using Indium-111 DTPA as radiolabel) and in women via magnetic resonance imaging (MRI, using a gadolinium chelate as contrast agent). A conventional cream formulation was used as reference in both studies. MethodCream and pellets were administered to sheep (n=6) in a two period-two treatment study and to healthy female volunteers (n=6) via a randomized crossover trial. Pellets (filled into hard gelatin capsule) and cetomacrogol cream, both labeled with Indium-111 DTPA (for gamma scintigraphy) or with gadolinium chelate (for MRI) were evaluated for their intravaginal distribution and retention over a 24h period. Spreading in the vagina was assessed based on the part of the vagina covered with formulation (expressed in relation to the total vaginal length). Vaginal retention of the formulation was quantified based on the radioactivity remaining in the vaginal area (sheep study), or qualitatively evaluated (women study). ResultsBoth trials indicated a rapid distribution of the cream within the vagina as complete coverage of the vaginal mucosa was seen 1h after dose administration. Clearance of the cream was rapid: about 10% activity remained in the vaginal area of the sheep 12h post-administration, while after 8h only a thin layer of cream was detected on the vaginal mucosa of women. After disintegration of the hard gelatin capsule, the pellet formulation gradually distributed over the entire vaginal mucosa. Residence time of the pellets in the vagina was longer compared to the semi-solid formulation: after 24h 23±7% radioactivity was detected in the vaginal area of the sheep, while in women the pellet formulation was still detected throughout the vagina. ConclusionA multi-particulate system containing starch-based pellets was identified as a promising novel vaginal drug delivery system, resulting in complete coverage of the vaginal mucosa and long retention time.