Rheological study and sensory analysis about four commercial detergents called “gel-detergents”

Gel detergents possess some advantages compared to podwer detergents, such as easyness to transport, high eficiency considering number of washes per bottle and the reasonable use of water and package. In order to check if a specific product shows gel behaviour, rheological studies are carried out; namely, Small Amplitude Oscillatory Shear tests. With this in mind, we report the influence of temperature (5 – 40) ºC on the mechanical spectra of four commercial detergents whose labels claim they are gels. The experimental results obtained supported that two out of four samples exhibited the expected weak gel viscoelastic properties. The remaining two detergents showed typical viscoelastic behaviour of viscous solutions (liquid-like response instead of gel-like), whose structure is not significant. We also conducted stepwise flow curves in the same temperature range. Most detergents studied showed shear thinning properties, which fitted the power law equation. The results obtained supported that the more shear thinning was the detergent sample, the more marked gel-like properties were observed. Finally, a sensory analysis was carried out in order to know the perception of the gel character for 30 panelists.Los detergentes gel poseen ciertas ventajas frente a los detergentes en polvo que los hacen muy interesantes, como facilidad en el transporte, alta eficiencia considerando el número de lavados por botella y el uso razonado de agua y embalaje. Para comprobar si un determinado producto tiene comportamiento gel, se realizan estudios reológicos; concretamente, ensayos en cizalla oscilatoria. Con este fin, en este estudio, se muestra la influencia de la temperatura (5 a 40 ºC) en el espectro mecánico de cuatro productos comerciales en cuyas etiquetas aparece la información de que son geles. Los resultados experimentales obtenidos demuestran que solo dos de las cuatro muestras exhiben las propiedades reológicas esperadas. Los dos detergentes restantes muestran propiedades de disoluciones viscosidad (respuesta líquida en vez de respuesta gel), cuya estructura no es significativa. También se llevaron a cabo curvas de flujo en el mismo rango de temperaturas. La mayoría de los detergentes mostraron comportamiento pseudoplástico, el cual se ajustó a la ley de la potencia. Los resultados obtenidos revelaron que el detergente con mayor grado de pseudoplasticidad fue el que mostro mayor carácter gel. Por último, se realizó un análisis sensorial para conocer la percepción de 30 panelistas del carácter gel de estos detergentes.Ministerio de Economía y Competitividad del Gobierno de España y por la Comisión Europea (Programa FEDER

Relationship of rheological and microstructural properties with physical stability of potato protein-based emulsions stabilized by guar gum

Despite potato protein is a great potential ingredient in food products due to its nutritional quality, it is not useful for the formation of sufficiently stable emulsions. For this reason, a widely used polysaccharide in the food industry, Guar gum, was added. The addition of guar gum to potato protein-based emulsions results in enhanced stability as demonstrated by the cooperative information provided by the combination of different techniques (rheology, optical microscopy and multiple light scattering). We established a relationship between a critical time for the onset of creaming and two rheological functions, namely the zero shear viscosity and the storage modulus. In addition, we propose a fast rheological method consisting of non-linear creep tests to detect shear-induced microstructural transitions

Injectable Hydrogels Based on Pluronic/Water Systems Filled with Alginate Microparticles for Biomedical Applications

A (model) composite system for drug delivery was developed based on a thermoresponsive hydrogel loaded with microparticles. We used Pluronic F127 hydrogel as the continuous phase and alginate microparticles as the dispersed phase of this composite system. It is well known that Pluronic F127 forms a gel when added to water in an appropriate concentration and in a certain temperature range. Pluronic F127 hydrogel may be loaded with drug and injected, in its sol state, to act as a drug delivery system in physiological environment. A rheological characterization allowed the most appropriate concentration of Pluronic F127 (15.5 wt%) and appropriate alginate microparticles contents (5 and 10 wt%) to be determined. Methylene blue (MB) was used as model drug to perform drug release studies in MB loaded Pluronic hydrogel and in MB loaded alginate microparticles/Pluronic hydrogel composite system. The latter showed a significantly slower MB release than the former (10 times), suggesting its potential in the development of dual cargo release systems either for drug delivery or tissue engineering

Shear-induced microstructural transitions in aqueous systems containing an esterquat cationic surfactant

Se presenta un estudio basado en técnicas reológicas y de microscopía electrónica de barrido de bajas temperaturas (cryo-SEM) sobre los cambios de microestructura provocados por el flujo en cizalla de dispersiones acuosas de un tensioactivo catiónico tipo esterquat. Se comparan micrografías de cryo-SEM y las respuestas bajo cizalla oscilatoria de dispersiones sin y con cloruro de calcio. Esta última no presenta zona de comportamiento viscoelástico lineal, apuntando su respuesta no lineal a un fenómeno de estructuración inducida por cizalla. Ensayos transitorios de inicio al flujo, entre 0,1s-1 y 2000s-1, confirman que se producen aumentos de viscosidad más acusados con el tiempo de flujo a medida que aumenta la velocidad de cizalla. La técnica de cryo-SEM apoya que los resultados transitorios se deben a que un exceso de energía mecánica provoca transiciones de bicapas de tensioactivo a vesículas. Diferentes ensayos reológicos realizados en serie avalan la naturaleza irreversible, en la escala de tiempo de esta investigación, de las transiciones microestructurales inducidas por cizalla. Se demuestra que a pesar de la presencia de cloruro de calcio (0,1%), la aplicación de una velocidad de cizalla excesiva puede dar lugar a la aparición de respuestas viscoelásticas lineales significativas.This paper deals with a rheological and microstructural (cryo- SEM) characterization of shear-induced microstructure transitions in aqueous dispersions of an esterquat cationic surfactant. Cryo-SEM micrographs and oscillatory shear results of systems containing or not calcium chloride are compared. The addition of calcium chloride precluded the occurrence of significant viscoelastic properties and the estimation of the linear viscoelastic range. The non-linear oscillatory response pointed to the occurrence of incipient shear-induced build-up phenomena. Start-up flow tests between 0.1s-1 and 2000s-1 showed that the increase of viscosity with shear time was more marked as shear rate was increased. Cryo-SEM observations supported that build-up results in transient flow were due to an excess of mechanical energy, which resulted in transitions from surfactant bilayers to vesicles. Several series of rheological tests were carried out to demonstrate that shear-induced microstructure transitions were irreversible in the time scale of this investigation. Despite the addition of calcium chloride (0.1% wt), the shear-induced dispersion of vesicles may provoke the onset of significant linear viscoelasticity.Es presenta un estudi basat en tècniques reològiques i de microscòpia electrònica d’escombratge de baixes temperaturas (cryo-SEM) sobre els canvis de microestructura provocats pel flux en cisalla de dispersions aquoses d’un tensioactiu catiònic tipus esterquat. Es comparen micrografies de cryo-SEM i les respostes sota cisallament oscil•latòri de dispersions sense i amb clorur de calci. Aquesta darrera no presenta zona de comportament viscoelàstic lineal, apuntant la seva resposta no lineal a un fenomen d’estructuració induïda per cisallament. Assaigs transitoris d’inici al flux, entre 0,1s-1 y 2000s-1, confirmen que es produeixen augments de viscositat més acusats amb el temps de flux a mesura que augmenta la velocitat de cisallament. La técnica de cryo-SEM recolza que els resultats transitoris es deuen a que un excés d’energia mecànica provoca transicions de bicapes de tensioactiu a vesícules. Diferents assaigs reològics realitzats en sèrie avalen la naturalesa irreversible, a la escala de temps d’aquesta investigació, de les transicions microestructurals induïdes per cisallament. Es demostra que, tot i la presència de clorur de calci (0,1%), l’aplicació de una velocitat de cisallament excessiva pot donar lloc a l’aparició de respostes viscoelàstiques lineals significatives

Injectable hydrogels based on pluronic/water systems filled with alginate microparticles: Rheological characterization

In this paper the rheological characterization of Pluronic/water systems filled with alginate microparticles is presented. The rheological characterization of the Pluronic/water systems allowed for the choice of the best Pluronic concentration taking into account its applications as injectable hydrogels for tissue repair. The effect on the rheological behavior of the addition of alginate microparticles, to be loaded with the drug, was analyzed and the maximum concentration of microparticles determined.Spanish Ministerio de Economia y CompetitividadV Plan Propio Universidad de SevillaEuropean Union (EU)Portuguese Foundation for Science and Technology 288 UID/CTM/50025/201

Influence of the formulation on double emulsions containing ecological ingredients prepared by a microfluidic technique

Multiple emulsions have significant potential in myriad applications, including foods, cosmetics, drop networks, controlled microreactors, synthesis of microcapsules and drug delivery systems. Great control of multiple-emulsion drops production can be achieved using microfluidic devices. The field of emulsification through microfluidic devices has in recent years become a popular topic of research. In this work, we used a practical approach to make monodisperse double-emulsions drops with an ultrathin middle layer using a single step emulsification in a capillary microfluidic device. The goal of this study was to investigate the influence of different surfactants and additives on stability and droplet size of W/O/W eco-friendly emulsions formulated with a green solvent (D-Limonene). The incorporation of Pluronic F108 destabilised the double emulsions due to a process of precipitation, forming microcapsules. By contrast, there was a necessity to include Span 80 in the formulation in order to achieve stable double emulsions. The addition of rosin gum or silicone oil did not show any improvement in the stability of these complex emulsions. Finally, the formulation used in ultrathin shell microfluidic device did not produce stable double emulsions in the traditional microfluidic device.Las emulsiones múltiples tienen multitud de aplicaciones en la industria alimentaria, cosméticos, microreactores controlados, síntesis de microcápsulas y sistemas de liberación controlada. Se puede conseguir un gran control de la producción de gotas en emulsiones dobles usando técnicas microfluídicas. En este trabajo se desarrollaron emulsiones dobles formuladas con D-Limoneno usando un dispositivo de microfluídica en un solo paso. El D-Limoneno, el componente principal del aceite esencial de naranja, es un monoterpeno natural que tiene propiedades antioxidantes, bactericida, quimiopreventivas y terapéuticas. El objetivo del presente estudio fue investigar la influencia de diferentes tipos de tensioactivos y aditivos en la formulación de emulsiones dobles ecológicas tipo corteza-ultrafina-núcleo sobre la estabilidad física. Las emulsiones dobles tipo corteza ultra fina y núcleo preparadas con Pluronic P108 sufrieron un fenómeno de desestabilización debido a la precipitación de este tensioactivo polimérico creando microcápsulas. Las emulsiones dobles necesitaron un tensioactivo hidrófobo (Span 80) en la fase media para estabilizarlas. Se consiguieron emulsiones dobles estables utilizando Span 80 como tensioactivo en la fase oleosa y PVA en la fase exterior para la configuración tipo corteza ultrafina-núcleo. Estas condiciones no son extrapolables al tradicional dispositivo de microfluídica.Ministerio de Economía y Competitividad del Gobierno de España-CTQ2015-70700-PComisión Europea (Programa FEDER)-CTQ2015-70700-

Processing and formulation optimization of mandarin essential oil-loaded emulsions developed by microfluidization

Emulsions can be used as delivery systems for bioactive ingredients for their incorporation in food products. Essential oils are natural compounds found in plants that present antioxidant and antimicrobial activity. Therefore, the main goal of this work was to develop emulsions, containing mandarin essential oil stabilized by two food-grade surfactants and guar gum, and to evaluate their physical stability. The initial droplet size of emulsions developed by microfluidization was optimized, obtaining diameters below one micron regardless of the processing conditions. However, the emulsion processed at 25,000 psi and one pass exhibited the lowest mean droplet sizes and polidispersity, and therefore, a higher stability. Different ratios of Tween 80 and Span 80 were assessed as stabilizers. Results obtained indicated that the ratio of surfactants had a significant effect on the mean droplet sizes, physical stability, and rheological properties. Thus, we found that the optimum ratio of surfactants was 75/25 (Tween80/Span80) on account of the lowest droplet mean diameters, lack of coalescence, and a low creaming rate. The rheological characterization of the stable emulsions showed a shear thinning flow behavior, and G" (loss modulus) values higher than G0 (storage modulus) values, in all the frequency range. The rheological behavior may be governed by the guar gum, which was confirmed by field emission scanning electron microscopy (FESEM). This research can be considered as the starting point for future applications of mandarin essential oil in emulsions, which can be incorporated in products as food preservatives.Ministerio de Economía y Competitividad CTQ2015-70700-

Caracterització reològica d’una suspoemulsió comercial per a ús agroquímic

Se estudian las propiedades reológicas de una suspoemulsión comercial para uso agroquímico. Se comparan los resultados obtenidos mediante curvas de flujo y ensayos en cizalla oscilatoria de baja amplitud para cinco temperaturas distintas en el intervalo de 5 a 25ºC. Las curvas de flujo, ponen de manifiesto que la suspoemulsión se caracteriza por presentar un comportamiento pseudoplástico, menos acusado a medida que aumenta la temperatura, que se ajusta al modelo de Sisko. Barridos de esfuerzo realizados a 0,1Hz permiten determinar el reducido rango viscoelástico lineal de la suspoemulsión, que depende de la temperatura. Los espectros mecánicos, entre 3Hz y 0,01 Hz, revelan que el sistema manifiesta propiedades viscoelásticas con un comportamiento típico de gel débil. La aparición de un mínimo en el valor de G” respecto a la frecuencia ha permitido estimar el módulo plateau, el cual desciende con el aumento de temperatura según una ecuación tipo Arrhenius. Aún así, la suspoemulsión presenta un carácter elástico que favorece su estabilidad física con el tiempo de almacenamiento. Se ha demostrado además que el sistema no sigue la regla de Cox-Merz.This study deals with a rheological characterization of a commercial suspoemulsion used for agrochemical application. Steady state flow and low amplitude oscillatory shear (SAOS) behaviour at five different temperazatures in the range of 5 to 25 °C are compared. Flow curves revealed that the pseudoplastic behaviour obeying the Sisko model was less pronounced as temperature was increased. Stress sweeps performed at 0.1 Hz allowed to determine the small linear viscoelastic range of the suspoemulsion, which depended on the temperature. The suspoemulsion at the different temperatures studied exhibited the typical weak-gel viscoelastic behaviour under SAOS between 3 and 0.01 Hz. The occurrence of a minimum of G” allowed to calculate the “Plateau” modulus, which decreased with temperature according to an Arrhenius type equation. Despite of that, the suspoemulsion showed an elastic character, which favoured its physical stability. Also, It has been demonstrated that the system did not follow the Cox-Merz superposition rule.S’estudien les propietats reològiques d’una suspoemulsió comercial per a ús agroquímic. Es comparen els resultats obtinguts mitjançant corbes de flux i assajos en cisalla oscil•latòria de baixa amplitud per a cinc temperaturas diferents en l’interval de 5 a 25 ºC. Les corbes de flux, posen de manifest que la suspoemulsió es caracteritza per presentar un comportament pseudoplàstic, menys acusat a mesura que augmenta la temperatura, que s’ajusta al model de Sisko. Els escaneigs d’esforç realitzats a 0,1Hz permeten determinar el reduït rang viscoelàstic lineal de la suspoemulsió, que depèn de la temperatura. Els espectres mecànics, entre 3Hz i 0,01 Hz, revelen que el sistema manifesta propietats viscoelàstiques amb un comportament típic de gel feble. L’aparició d’un mínim en el valor de G” respecte a la freqüència ha permès estimar el mòdul plateau, el qual disminueix quan augmenta la temperatura segons una equació de tipus Arrhenius. Tot i això, la suspoemulsió presenta un caràcter elàstic que afavoreix la seva estabilitat física durant el temps d’emmagatzematge. S’ha demostrat a més que el sistema no segueix la regla de Cox-Merz.Ministerio de Ciencia e Innovación del Gobierno de EspañaBayer-Crop Scienc

Influence of the Homogenization Pressure on the Rheology of Biopolymer-Stabilized Emulsions Formulated with Thyme Oil

Different continuous phases formulated with ecofriendly ingredients such as AMIDET®N, an ecological surfactant, as well as welan and rhamsan gums were developed. An experimental design strategy was been in order to study the influence of the ratio of these two polysaccharides and the homogenization pressure applied in a microfluidizer on the critical shear stress for the continuous phases developed. A pure rhamsan gum solution was selected as the starting point for further study based on the production of thyme oil-in-water emulsions. The effect of the homogenization pressure on the physical stability, critical shear stress and droplet size distribution was analyzed for emulsions with optimized values of the rhamsan–welan ratio. These bioactive thyme oil-in-water emulgels could be considered as delivery systems with potential applications in the food industry.Ministerio de Economía y Competitividad CTQ2015-70700-PEuropean Commission (FEDER Programme