Peer Review Publications

Several food proteins, together with some naturally occurring water-soluble gums (viscosity builders) and lecithin, are evaluated as clouding agents for formulated orange drinks. The use of these three types of natural products represents a significant advantage over the present formulations in which synthetic emulsifiers and weighting agents are used. The effects of concentration of each of the above ingredients, pH, temperature and mode of preparation are explored and related to cloud stability, droplet size distribution and the opacity of the emulsion both in concentrated and diluted formulations. A mechanism for protein adsorption onto the droplets is suggested.
N Garti and A Kovacs. 1991. “Facilitated emulsion liquid membrane separation of complex hydrocarbon mixtures.” Journal of Membrane Science, 56, 3, Pp. 239–246. Abstract
Solvent extn. and sepn. of polar components from kerosine was based on the formation of an emulsion liq. membrane; such extns. were successful if a facilitating agent (e.g., N-methylpyrrolidone, I) was used in conjunction with a high HLB surfactant (e.g., Tween 20). Phase sepn. of an oil-in-water emulsion of kerosine and I dispersed in n-hexane was achieved in a mixer-settler (at 300-350 rpm) for 10 min.; mass transfer was estd. quant. Surfactants with low HLB inhibited sepn. of polar components but participated in the sepn. of apolar components. The emulsion system behaved like a regular liq.-liq. extn. process with increasing addns. of I in the presence of Tween 20; however, a lower yield of non-polar components was obsd. with increasing polarity of the permeate stream. [on SciFinder(R)]
N Garti, D OSTFELD, R GOUBRAN, and EJ Wachtel. 1991. “Solubilization of hydrocortisone in lyotropic liquid crystals.” Journal of Dispersion Science and Technology, 12, 3-4, Pp. 321–335. Abstract
The solubilization of hydrocortisone (HC) in lamellar liq. crystals (LC) contg. monoglyceride laurate (MGL) and water was studied. The max. capacity of the 70:30 (wt./wt.) MGL/water system to solubilize HC is larger than any other reported solubilization system (such as microemulsions and micelles), and exceeded 1.0 wt.%. The systems were tested by polarized light microscopy, small angle x-ray diffraction, DSC, and deuterium NMR. The addn. of HC caused no change in the interplanar spacing of the system, and had no effect on the gel-to-LC transition temp. However, the solubilization enlarged the quadrupole splitting of the water deuteron. These results suggest that the HC mols. are positioned in the vicinity of, or within, the polar head groups of the monoglyceride. [on SciFinder(R)]
Orange oil cloudy emulsions based on naturally occurring oil-soluble gum elemi and naturally occurring water-soluble gum arabic have been prepared and evaluated. Cloud and emulsion stability, as well as the opacity of each emulsion, were recorded and compared. It was demonstrated that the emulsion stability is determined by the gum elemi/orange oil ratio, the orange oil content, and the gum arabic/orange oil ratio. The opacity is a function of the orange oil content and to a lesser extent also depends on the gum elemi/orange oil ratio. Since the gum elemi/orange oil ratio is a critical parameter affecting both opacity and stability it should be carefully chosen and controlled. Gum arabic is not the sole emulsifier, as gum elemi also adsorbs on the oil droplets and plays a role in emulsion stability.
Shlomo Magdassi and Nissim. Garti. 1991. “Surface activity of proteins.” Surfactant Science Series, 39, Interfacial Phenom. Biol. Syst., Pp. 289–299. Abstract
A review, with 42 refs., on (1) adsorption at fluid-fluid interfaces, (2) surface activity response to factors, (3) adsorption at solid-liq. interfaces, (4) proteins at interfaces of biol. interest, and other topics. Proteins at surfaces in pharmaceutical and food industries as well as in natural processes are discussed. [on SciFinder(R)]
Dov Reichman and Nissim. Garti. 1991. “Galactomannans as emulsifiers.” Special Publication - Royal Society of Chemistry, 82, Food Polym., Gels, Colloids, Pp. 549–556. Abstract
Carob or guar gum was used as the only emulsifier in the prepn. of nonviscous oil-in-water food model emulsions, and the structure and properties of the emulsions were studied. Microscopy under polarized light showed liq. crystals of the gums arranged in Maltese cross shapes around the oil droplets. The gums adsorbed on oil droplets, formed layers of lamellar liq. crystals, and enhanced emulsion stability to coalescence and flocculation. [on SciFinder(R)]
The role of emulsifiers in polymorphic transformations of fats and fatty acids is treated in this paper. Their effect as crystal modifiers in soln.-mediated transformations (in fatty acids) is compared to that of a dynamic controller of polymorphic transformations in triglycerides. The importance of chem. structure both in the hydrophilic and in the hydrophobic moieties of the emulsifier for an inhibitory effect on phase transitions has been emphasized. The emulsifier soly. and crystn. behavior in different solvents are probably the main factors affecting its ability to interfere with the kinetics of soln.-mediated transformations. On the other hand, certain requirements for a specific chem. structure of the emulsifier which provides good structure compatibility must be met to affect the kinetics and mechanism of solid-solid or melt-mediated transformations. A mechanism of emulsifier incorporation in the fat and its effect in delaying the polymorphic transformation of tristearin is proposed. It has been concluded that the presence of the emulsifier does not dictate the formation of any preferred polymorph but rather controls the mobility of the mols. and their facility to undergo polymorphic transformations. The relationship between polymorphism in fats and presence of additives plays a major role in the food industry, because of the serious quality implications involved in phase transitions. [on SciFinder(R)]
Dov Reichman and Nissim. Garti. 1990. “Interaction of galactomannans with ethoxylated sorbitan esters. Surface tension and viscosity effects.” In Gums Stab. Food Ind. 5, [Proc. Int. Conf.], 5th, Pp. 441–446. IRL. Abstract
In the present work, surface tensions of LBG (locust bean) and guar gum have been studied. It has been demonstrated that galactomannans, although highly hydrophilic in nature, can adsorb at interfaces, reducing surface tension to levels whereby they can be categorized as surfactants. Surface tensions of LBG solns. with ethoxylated sorbitan trioleate indicate the formation of a new species (complexes) with improved surface properties. The viscosities of aq. solns. of guar gum, LBG and their mixts. with ethoxylated mono- and trioleates (Tween 80 and 85) were measured at different shear rates. At high emulsifier concns. (5.0 gr/dL) a significant increase in viscosity is shown with Tween 85 in comparison to a sharp decrease with Tween 80. Both LBG and guar gum exhibited similar performance. The results are discussed in relation to the mol. structure of the galactomannan-emulsifier complex and the hydrophobicity of the constituents. [on SciFinder(R)]
A Aserin, N Garti, and E YANIR. 1989. “New surfactants for soluble extreme pressure cutting oils.” Journal of Dispersion Science and Technology, 10, 3, Pp. 251–264. Abstract
Brominated or chlorinated nonionic surfactants for sol. extreme pressure cutting oils are significantly more efficient than cycloparaffins. The performance of the surfactants is a function of the emulsion stability and its availability to the surface in contact with the metal. Surfactants with sufficient Cl or Br contents have excellent wear and friction properties. [on SciFinder(R)]
M FRIEDMAN and N Garti. 1989. “Preparation and surface properties of new sulfosuccinic derivatives of fatty polyglycerol esters.” Journal of Dispersion Science and Technology, 10, 3, Pp. 285–306. Abstract
Oligomeric polyglycerol was esterified with C12-16 fatty acids and then maleated. The maleates were sulfonated with Na2SO3 to give anionic sulfosuccinate surfactants. Higher crit. micelle concn. (CMC) and better foaming performance but lower wetting power were obtained by increasing the hydrophilic chain length to d.p 6; above this length the opposite trend was noted. A linear relation between hydrophobic chain length and log(CMC) was obsd. Optimization of surface properties could be obtained by regulating the maleation conditions. [on SciFinder(R)]
N Garti, JS ARONHIME, and S SARIG. 1989. “The role of chain length and an emulsifier on the polymorphism of mixtures of triglycerides.” JAOCS, J. Am. Oil Chem. Soc., 66, 8, Pp. 1085–1089. Abstract
The appearance of the $\beta$' form in the $\alpha$-$\beta$ transformation in tristearin was hardly detectable. On the other hand, in mixts. of tristearin and tripalmitin at different ratios, $\beta$' formation was favored. This observation confirmed the statement in the literature that in mixts. of different chain lengths orthorhombic packing was stabilized. When an emulsifier (sorbitan monostearate) was added to the mixts., both the $\beta$' and $\beta$ formation were inhibited. The effect caused by the addn. of the emulsifier as an impurity to tristearin was compared to that caused by the addn. of tripalmitin: their effects, although both kinetic, were very different. [on SciFinder(R)]
Olga Jacome Guth, Judith Aronhime, Nissim. Garti, OJ GUTH, Judith Aronhime, and Nissim. Garti. 1989. “Polymorphic transitions of mixed triglycerides, SOS, in the presence of sorbitan monostearate.” JOURNAL OF THE AMERICAN OIL CHEMISTS SOCIETY, 66, 11, Pp. 1606–1613. Abstract
The polymorphic behavior of 1,3-distearoyl-2-oleoyl glycerol (SOS) was investigated in the presence of a selected food emulsifier, sorbitan monostearate. Five polymorphs, named $\alpha$, $\gamma$, pseudo-$\beta$', $\beta$2, and $\beta$1, were crystd. and identified by x-ray anal. and DSC. Each polymorph was treated with 2 selected protocols - the screen cycle and the aging cycle. Sorbitan monostearate, when present in the molten fat, retarded the $\alpha$ to $\gamma$ transition during both the screen cycle and the aging cycle. A retardation effect was not detected for the $\gamma$ to pseudo-$\beta$' transition (during the screen or the aging cycle). The emulsifier inserted into the fat behaved as a conventional impurity, causing significant redn. in the melting temps. of each polymorph. As a result, the fat tended to melt prior to its transition. The behavior of SOS in the presence of the sorbitan monostearate is therefore different from that of SSS (tristearin), and may explain, in part, the absence of the strong blooming transition to high melting polymorph that occurs when the fat is rich in SOS. This behavior can also shed some light on the behavior of cocoa butter in the presence of sorbitan esters. [on SciFinder(R)]
Jannet Rozenblat, Shlomo Magdassi, and Nissim. Garti. 1989. “Effect of electrolytes, stirring and surfactants in the coacervation and microencapsulation processes in presence of gelatin.” Journal of Microencapsulation, 6, 4, Pp. 515–526. Abstract
The parameters affecting simple coacervation and the ability to encapsulate oleic acid using this technique were investigated. Coacervation was achieved using different types of gelatin (bloom no., charge) and various electrolytes. The electrolytes used for the coacervation can be divided into 3 groups: (1) inert salts; (2) phase sepn. inducers, (a) pptn. inducing agents (PIA), and (b) coacervation inducing agents (CIA); and (3) coacervation inhibiting agents. The encapsulation of oleic acid was evaluated with two types of gelatin and various emulsifiers (anionic, cationic, and nonionic). For pos. charged gelatin, the encapsulation is incomplete in presence of cationic emulsifiers. For neg. charged gelatin no general trend was obsd. The stirring rate for each step of the prepn. of the microcapsules was evaluated. High stirring is essential only in the cooling stage. The study was carried out in view of encapsulation of particular bacteria dispersed in the oil phase. [on SciFinder(R)]