Effect of Tween Emulsifiers on the Shear Stability of Partially Crystalline Oil-in-Water Emulsions Stabilized By Sodium Caseinate (original) (raw)
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Colloids and Surfaces A-physicochemical and Engineering Aspects, 2003
Confectionery coating fat (CCF ) emulsions (40 wt.%) were prepared by mixing liquid fat with solutions (1 Á/4 wt.%) of selected polymeric and small molecule surfactants, and homogenizing to a mean particle diameter of 0.719/0.05 mm. Aliquots of the emulsions were temperature cycled (40 to (/10 to 40 8C at 1.5 8C min (1 ) four times in a differential scanning calorimeter. The stable emulsion droplets crystallized at 0 Á/6 8C (depending on the type of emulsifier) while the non-emulsified fat crystallized at Â/15 8C. The ratio of the enthalpies at these temperatures was used to calculate the proportion of the emulsion that had destabilized after each thermal cycle. All of the small molecule-stabilized emulsions largely destabilized after one cycle. The caseinate-stabilized emulsions were relatively resistant to several thermal cycles unless ethanol (30 wt.%) was added or the pH lowered to 5, in both cases they destabilized during the first cycle. When a small molecule surfactant was added to displace the caseinate from the interface, there was a sharp reduction in stability at the surfactant to protein molar ratio R !/25. Whey protein-stabilized emulsions were partly unstable to freeze Á/thaw even following a thermal pretreatment to denature the proteins. Cryo-SEM confirmed the destabilization of the emulsions was due to partial coalescence. #
Water-in-triglyceride oil emulsions. Effect of fat crystals on stability
Journal of The American Oil Chemists Society, 1995
The influence of low concentrations (0.1-5%) of fat crystals on the stability of water-in-soybean oil emulsions was examined by light scattering and sedimentation experiments. Both the initial flocculation/coalescence rate and long-term stability against water separation were determined. The initial flocculation/coalescence rate increased upon addition of small amounts of fat crystals. When the crystal concentration was increased above a critical concentration (specific to a system), a decrease in the flocculation/coalescence rate occurred. The increased flocculation/coalescence rate is likely the effect of bridging of water droplets by fat crystals. Fat crystal wetting by water is an important criterion for this phenomenon to occur. Emulsion stabilization for crystal concentrations above critical is caused by a mechanical screening of water droplets. The presence of considerable amounts of crystals in oil also lowered the density difference between droplet and medium, and enhanced viscosity. The degree of increase in viscosity depended upon the emulsifier. Both a decrease in density difference and an increase in viscosity play a role in hindering flocculation/coalescence of droplets. In long-term studies of water separation, all concentrations of fat crystals stabilized the water-in-oil emulsions. The droplet size of these emulsions increased until the critical droplet size was approached where the screening effect of crystals on the droplets no longer stabilized the emulsions. The stabilizing effect for emulsions with monoolein was continuously improved by increasing the amount of crystals up to 5%. For lecithin-stabilized emulsions, an optimal effect was achieved for fact crystal concentrations of 1–2%.
Journal of The American Oil Chemists Society, 2003
A double emulsion system [oil-in-water-in-oil (O/W/O)] with 16.3% (w/w) water and 83% (w/w) oil was prepared and stabilized using a novel method of mixing two oil-in-water (O/W) emulsions together. The first emulsion consisted of 85% (w/w) liquid canola oil, 14.4%(w/w) water, 0.5% (w/w) sodium caseinate, and 0.1% (w/w) lecithin and the second emulsion contained 73% (w/w) canola oil, 8% (w/w) palm-cotton stearin (50∶50), 0.2% (w/w) lecithin, 18.2% (w/w) water, and 0.6% (w/w) sodium caseinate. Mixing the two emulsions (50∶50) by weight produced a product with 79% (w/w) liquid canola oil and 4% (w/w) palm-cotton stearin. The two O/W emulsions were prepared separately at 50°C, mixed together at 45°C for 2–5 min, and then supercooled in a −5°C ice/salt bath while mixing at low shear rates (2,000–3,000 rpm). Under supercooling conditions the fat globules in the second emulsion (containing liquid oil and stearin) began to break down as a result of fat crystal growth and shearing action and release plastic fat. During this stage, the continuous aqueous phase underwent a phase transition and the emulsion viscosity dropped from 37,000–50,000 to 250 cP. The released plastic fat continued to harden as the temperature dropped and stabilized the first O/W emulsion (containing only liquid oil). The low shear rate mixing was stopped when the temperature dropped below 15°C and before the O/W/O emulsion hardens. Microstructural analysis of the first emulsion before and after supercooling showed essentially intact fat globules. The microstructure of the second emulsion before supercooling showed the same intact globules as the first emulsion, but after supercooling, an amorphous mass with only a few intact globules was seen. By mixing the two emulsions together and supercooling, a stable O/W/O emulsion was formed with plastic fat as the continuous phase and the first O/W emulsion as the dispersed phase.
Food Research International, 2013
The effect of selected monoglycerides on droplet morphology and rheology of palm kernel oil emulsions was studied. Combination of lactic acid ester of monoglycerides (LACTEM) and unsaturated monoglycerides (GMU) yielded highly viscous emulsions caused by partial coalescence. LACTEM combined with saturated monoglycerides (GMS) or diacetyl tartaric acid ester of monoglycerides (DATEM) gave low-viscous emulsions. The rheological behavior was found not to be related to polymorphic transformations of fat in the emulsions. A possible relationship between structural changes of emulsions and the effect of monoglyceride crystallization behavior of PKO was examined by studying the monoglycerides' influence on crystallization of bulk PKO. Polymorphic transformation, crystallization kinetics and melting/crystallization profile of bulk PKO were analyzed. The monoglycerides had minor effect on crystallization behavior of bulk PKO compared to the major impact on emulsion stability. This indicates that emulsifiers act differently in bulk and dispersed fat. For PKO the structural changes of the emulsions were independent of the effects of monoglycerides on the crystallization of bulk fat.
Journal of the American Oil Chemists' Society, 2008
The objective of this research was to systematically study the effect of processing conditions on the crystallization behavior and destabilization mechanisms of oil-in-water emulsions. The effect of crystallization temperature (T c) and homogenization conditions on both thermal behavior and destabilization mechanisms were analyzed. Results show that the crystallization of lipids present in the emulsions was inhibited when compared with bulk lipids as evidenced by a lower onset and peak temperature (T on and T p , respectively) in differential scanning calorimetry crystallization exotherms. The smaller the droplet size in the emulsion, the more significant the inhibition (lower T on and T p). Lower values of T on and T p were not necessarily indicators of emulsion stability. Homogenization conditions not only affected the T on and T p of crystallization but also the crystallization profile of the samples. Lipids present in emulsions with small droplets were crystallized and melted in a less fractionated manner when compared to lipids in bigger droplets or even to the bulk lipids. The amount of lipid crystallized as evidenced by enthalpy values, did not have a direct relationship with the emulsions stability. Although enthalpy values increased as T c decreased, the destabilization kinetics did not follow the same tendency as evidenced by back scattering measurements.
Effect of Oils with Different Fatty Acids Profile on the Physical Properties of Formulated Emulsion
2015
The effects of different fatty acids composition of oils on the physical properties of formulated oil emulsions were investigated. To achieve this goal, milk fat as the choice on the basis it contains saturated fatty acids (SFAs) higher than unsaturated fatty acids (USFAs) (~ 2:1), while the choice of palm oil on the basis it contains SFAs equal to the USFAs (~ 1:1), and commercial oil consists of soybean, cottonseed and coconut oils on the basis it contains SFAs lower than USFAs (~ 1:2). Oil emulsions (20% oil w/w) were formulated with 20% melted butter oil (FBO), palm oil (FPO), oils blend (FOB), butter oil and palm oil (FBOPO) (1:1) or butter oil and oils blend (FBOOB) (1:1), and 80% reconstituted skim milk. The results revealed that surface tension, protein load and viscosity were the highest in FOB, but those were the lowest in FPO and FBOPO. Inversely, FBO and FBOPO had the best foaming capacity, while FOB had the lowest foaming capacity. The amount of freeze-thaw serum leakag...
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2019
Water-in-oil-in-water (W/O/W) technology enables the development of an emulsion-based delivery system for functional food applications. The functionality of this system depends on the oil barrier of the double emulsion, whereby the fat matrix properties (e.g. solid fat content) play an important role. First, the effect of W/O/W emulsification on fat crystallization and melting behavior was studied and compared to bulk fat. Second, the effect of fat composition was investigated. As such, W/O/W emulsions were produced with a slow and fast crystallizing fat, i.e. soft palm mid fraction (sPMF) and partially hydrogenated sunflower oil, respectively, upon cooling and subsequent isothermal crystallization. Low resolution NMR and DSC techniques were applied, and indications about the polymorphic behavior were verified by real-time synchrotron XRD measurements. Except from increased supercooling, the overall fat crystallization dynamics in the W/O/W emulsions were similar to bulk, irrespective of the used fat. Yet, broadening of the long spacing peaks in the W/O/W emulsions indicated less ordered triacylglycerol longitudinal stacking compared to bulk. This effect was more pronounced in case of α-crystals than β'-crystals. With respect to W/O/W functionality, the-XRD (X-ray diffraction)
Rheological and physical analysis of oil-water emulsion based on enzymatic structured fat
Rheologica Acta, 2020
Structured triacylglycerols play an important role in determining the functional properties of fat-based emulsion products. The aim of the study was to evaluate the physical properties of the emulsion systems manufactured on the basis of enzymatically modified rabbit fat with pumpkin seed oil in the presence of sn-1,3 regioselective lipase. Emulsions containing variable contents of thickener and variable fat ratios were analyzed for rheological behavior and particle size changes during storage, and their stability was assessed using the Turbiscan test. The results showed that the emulsion containing the majority of rabbit fat and 1 wt% of carboxymethylcellulose was characterized by the highest stability. On the other hand, the emulsions containing higher amounts of pumpkin seed oil in a fatty base characterized the lowest resistance to destabilization processes. The research confirmed the possibility of producing structured fat which can be the basis for new emulsion systems propose...