P. Dokić

Influence of different maltodextrins on properties of O/W emulsions

Abstract Maltodextrins, low converted products of starch hydrolysis, are used in various emulsions to provide desirable viscosity, texture and mouthfeel. In order to assess behaviour of such emulsions in process of production (emulsification) as well as end products in application (pouring, spreading) it is necessary to investigate emulsification dynamics, globule size changes and rheological behaviour. In this work emulsification dynamics and the influence of different factors on dispersion and rheological characteristics of sunflower oil in water emulsions stabilized with food grade emulsifier with addition of maltodextrins were studied. Influence of oil and maltodextrin concentration and partial substitution of oil with equivalent quantity of maltodextrin were investigated, too. It was concluded that certain specific maltodextrin characteristics such as DE value (dextrose equivalent-measure of the degree of starch polymer hydrolysis) i.e. size of maltodextrin molecules significantly influence dispersion and viscous properties and stability of emulsions. With increase of oil concentration for the same concentration of maltodextrin in continuous phase emulsions undergo changes in flow type from shear-thinning to thixotropic and antithixotropic. Antithixotropy induced by shear, was result of formation of network due to two competing factors: orientation of deformed oil droplets and maltodextrin molecules and linking of oil droplets through maltodextrin molecules.

Action of emulsifiers during homogenization of o/w emulsions

Droplet size and size distribution changes at homogenization of paraffin oil emulsions, stabilized by different concentrations of various emulsifiers, were investigated. During homogenization, samples were taken from emulsions and the most frequently occuring diameter, mean droplet diameter and standard deviation (distribution width) were determined. Mathematical relations describing changes of mean diameter and distribution width, as a function of the homogenization period and emulsifier concentration, were derived and applied to the experimental data. Emulsifier efficiencies and capabilities were characterized by physical constants and graphically. Optimal homogenization time interval, optimal emulsifier concentrations and corresponding droplet size distribution parameters were computed.

Colloid Characteristics and Emulsifying Properties of OSA Starches

The objective of this paper was to characterize commercially available octenyl-succinate starches (OSA starches), Purity Gum 2000 and Hi-cap 100, by determining their viscous behaviour and characteristics and molecular mass, as well as to examine their emulsifying properties in corn oil-in-water emulsion system.

Study on thermal induced phase inversion of concentratedO/W emulsions stabilized by various tween emulsifiers

SummaryThermal induced phase inversion of concentrated oil-in-water emulsions stabilized by various fatty acid polyoxyethylene esters of sorbitan (Tween 21, Tween 61, Tween 65, Tween 80 and Tween 81) has been studied. Phase inversion temperature (PIT) was determined by differential thermal analysis and the changes in internal structure of emulsions caused by heating were followed microscopically. The PITS obtained were dependent on the kind of Tween. When the emulsions were stabilized by Tween 65, the PIT also depended on whether the emulsifier was dissolved in water or in oil phase or in the both. Microscopic examination of the emulsions during heating showed that the appearance of water droplets within the oil drops, i.e. the development of a multiphase (W/O/W) emulsion structure precedes phase inversion.ZusammenfassungDie thermische Phaseninversion konzentrierter Öl-in-Wasser-Emulsionen (durch verschiedene Emulgatoren des Tween-Typs stabilisiert) wurde untersucht und die Phasen-inversionstemperatur durch Differentialthermoanalyse bestimmt.Die Phaseninversionstemperatur hängt von der Tweenart ab. Mit Tween 65 ist die Phaseninversionstemperatur auch davon abhängig, ob der Emulgator in Wasser, in Öl oder in beiden Phasen gelöst wird. Mikroskopische Untersuchungen haben gezeigt, daß Wassertröpfchen innerhalb der Öltropfen entstehen, d. h., daß die Entwicklung einer mehrphasigen Wasser-Ö1-Wasser-Struktur der Phaseninversion vorangeht.

Investigation on the particle size distribution of O/W emulsions

SummaryThe aim of this research has been the investigation of a general equation of the particle size distribution in emulsions, applicable to different emulsions, especially to particle size distribution at homogenization processes.It has been supposed that at homogenization particles tend to assume a characteristic, most probable diameterX, due to different conditions, so that bigger particlesX disintegrate, while smaller ones coalesce. It may be assumed that the “ability” of altering particles of a certain diameterx depends, in that case, on the difference (X−x). The speed of particle number alterations at their diameter, i. e.dn/dx may be presented by the eq. [1], which when integrated gives a statistic distribution eq. [2] having a function form, i.e.:

MATHEMATICAL AND EXPERIMENTAL ESSENTIALS OF THE MULSIFICATION PROCESS: OPTIMAL PARAMETERS DETERMINATION

\frac{n}{N} = \frac{{a^{aX + 1} }}{{\Gamma (aX + 1)}}x^{aX} e^{ - ax}

Rheological characteristics of β-lipoproteins

wherea andX are the constants,n—the particle number of diameterx, andN—the total particle number.Experimental checkings proved satisfactory regarding the emulsions O/W, which differ in their characteristics and composition. The equation has also proved satisfactory for the emulsions of identical composition, homogenized for different periods of time, as well as for the ones that suffered certain particle distribution due to aging.ZusammenfassungZiel der Forschung war, eine allgemeine Gleichung des Verteilens der Tröpfchengröße in den Emulsionen zu finden. Diese Gleichung sollte für die verschiedenen Emulsionen, besonders bei der Verteilung der Tröpfchengröße in dem Prozeß der Homogenisierung, gelten.Es ist dargestellt, daß Tröpfchen während der Homogenisierungszeit streben, einen charakteristischen wahrscheinlichen DurchmesserX zu bekommen, was in der Abhängigkeit von den verschiedenen Bedingungen steht, so daß im Prozeß der Homogenisierung alle größeren Tröpfchen vonX zerfallen, und alle kleineren vonX koaleszieren werden. Man kann annehmen, daß die „Fähigkeit“ des Wechseins der Tröpfchengröße mit irgendeinem Durchmesserx, in diesem Zufall von dem Unterschied ¦X−x¦ abhängig ist. Die Schnelligkeit des Wechselns der Tröpfchenzahl mit ihren Durchmesser, d. h.dn/dx, kann durch die Abhängigkeit, die mit der Gl. [1] gegeben ist, dargestellt werden. Diese Gl. [1] gibt, nach der Integration, die statistische Gleichung des Verteilens [2], die eine Gammafunktion besitzt, d. h.