All Publications

Judith Schlichter Aronhime, Sara Sarig, and Nissim. Garti. 1988. “Reconsideration of polymorphic transformations in cocoa butter using the DSC.” JAOCS, J. Am. Oil Chem. Soc., 65, 7, Pp. 1140–1143. Abstract
Cocoa butter was crystd. in the differential scanning calorimeter in the presence and the absence of sorbitan monostearate at different cooling rates. The solidification and fusion curves were recorded. The cooling rate affects enthalpies and temps. of phase transitions. Very slow cooling causes a significant decrease in crystn. enthalpy, suggesting that fractionation of glycerides occurs under these conditions. In the presence of 5% sorbitan monostearate, cooling and heating curves of cocoa butter are sharper, the solidification point is higher, and the fusion point is slightly lower; further, both crystn. and fusion enthalpies are lower than in pure cocoa butter. The presence of the emulsifier seems mainly to promote fractional crystn. Fusion curves after different periods of isothermal crystn. suggest that higher polymorphic forms differ in chem. compn. from lower ones, and that the presence of sorbitan monostearate affects the fractionation in the fat. [on SciFinder(R)]
Judith Schlichter Aronhime, Sara Sarig, and Nissim. Garti. 1988. “Dynamic control of polymorphic transformation in triglycerides by surfactants: the Button Syndrome.” JAOCS, J. Am. Oil Chem. Soc., 65, 7, Pp. 144–150. Abstract
The kinetics of polymorphic transformations in monoacid satd. triglycerides and the effect of the presence of certain solid surfactants were investigated. Selected emulsifiers can be incorporated at the level of 10% by wt. within the triglyceride, without changing the crystal lattice; on the other hand, their presence affects the heat capacity of the triglyceride and the NMR relaxation time T1. Following the polymorphic transformation both during aging and during heating in the DSC, both the mechanism and rate of transformation of the triglyceride strongly depend on the kinetic conditions and on its own chem. structure. In conjunction with these results, the effect of the emulsifier is strongly dependent on the transformation conditions. The kinetic effect of the additive on the solid-solid transformation was strictly assocd. with its hydrophilic moiety structure. A model of mol. incorporation describes the arrangement of the surfactant mols. parallel to the triglyceride chains and formation of vacancies. The selectivity of the additive concerning its effect of dynamic controller of polymorphic transformations was explained by its capacity to create H bonds with the neighboring triglycerides, which was called the Button Syndrome. [on SciFinder(R)]
R AZOURY, JS ARONHIME, S SARIG, S ABRASHKIN, I MAYER, and N Garti. 1988. “NMR relaxation studies to explore the role of emulsifier in tristearin polymorphic transformation.” JAOCS, J. Am. Oil Chem. Soc., 65, 6, Pp. 964–967. Abstract
Proton magnetic resonance measurements were performed on $\alpha$- and $\beta$-polymorphs of tristearin (I) crystals. The spin-lattice relaxation time (T1) was measured at 20 MHz and 37° on the pure I crystals and on I crystd. in the presence of different solid surfactants. A significant neg. correlation for T1 values and different compns. of $\alpha$- and $\beta$-polymorphs in a mech. mixt. was found. The shortening of T1 relaxation time of the $\beta$-form was different for the various types of the added surfactants while they had no effect on the relaxation time of the $\alpha$-form. A model was proposed according to which the presence of additives, such as surfactants, generated vacancies within the crystal lattice of I and enhanced the freedom of rotation of the fat mol. about the terminal carbon-carbon bond. [on SciFinder(R)]
N Garti, Judith Schlichter, and S SARIG. 1988. “DSC studies concerning polymorphism of saturated monoacid triglycerides in the presence of food emulsifiers.” Fett Wissenschaft Technologie, 90, 8, Pp. 295–299. Abstract
Trilaurin, trimyristin, tripalmitin, and tristearin heats of fusion of $\alpha$ and $\beta$ polymorphs and the heat of transition were detd. alone and in the presence of sorbitan and ethoxylated sorbitan fatty acid esters, glycerol 1-stearate, triglycerol 1-stearate, triglycerol 1-monooleate, and monoglyceride citric acid ester. The emulsifiers could affect melting of the $\alpha$ form and/or recrystn. of the $\beta$ form, depending on triglyceride chain length and emulsifier structure. All the solid emulsifiers suppressed crystn. of the higher triglycerides. The sorbitan satd. esters promoted melting of the $\alpha$ polymorph rather than transformation to the $\beta$ form, and the other surfactants had the opposite effect. Slower heating minimized the inhibition of $\beta$ crystn. of tristearin by solid emulsifiers. Emulsifiers apparently modify the kinetic character of triglyceride polymorphic transitions. [on SciFinder(R)]
R GOUBRAN and N Garti. 1988. “Stability of water in oil emulsions using high molecular weight emulsifiers.” Journal of Dispersion Science and Technology, 9, 2, Pp. 131–148. Abstract
Polymd. and crosslinked unsatd. glycerides were used as emulsifying agents (3-5%) for soybean oil, giving ≤50% aq. emulsions. The d.p., mol. wt. distribution, viscosity, dielec. const., and refractive index of the emulsifier were correlated with the emulsion stability, with mol. wt. ∼40,000 giving the best results. [on SciFinder(R)]
J SCHLICHTER, I MAYER, S SARIG, and N Garti. 1988. “The influence of emulsifiers on the crystal properties of tristearin and trilaurin.” Powder Diffraction, 3, 1, Pp. 19–22. Abstract
The effect of solid emulsifiers, added at the level of 10%, on the lattice parameters of tristearin and trilaurin, was studied by x-ray powder diffraction. The presence of sorbitan monostearate and glycerol-l-stearate affects slightly the lattice const. a in tristearin; on the other hand, although sorbitan monostearate causes an increase in a of trilaurin, glycerol-l-stearate does not. The presence of sorbitan monolaurate and glycerol-l-stearate affect a of trilaurin similarly to the long chain emulsifiers. A correlation between the effect on a and the increase in m.p. was found. The presence of the emulsifier does not alter drastically the lattice dimensions of the fat. The slight dissimilarity in crystal structure between tristearin and trilaurin is confirmed by the diverse effects of the emulsifiers on the internal structure of the fat. [on SciFinder(R)]
Judith Schlichter-Aronhime and Nissim. Garti. 1988. “Solidification and polymorphism in cocoa butter and the blooming problems.” Surfactant Science Series, 31, Cryst. Polymorphism Fats Fatty Acids, Pp. 363–393. Abstract
A review and discussion with 74 refs. The chem. properties, compn., phase behavior and polymorphism, with and without added fats and impurities, are discussed with respect to the bloom problem and the role of tempering. [on SciFinder(R)]
Ran Shelef and Nissim. Garti. 1988. “Polymorphic transitions in hydrogenated canola oil in presence of surfactants.” Thermochimica Acta, 134, Pp. 97–106. Abstract
The polymorphic transitions of hydrogenated canola oil in the presence of some selected food emulsifiers such as sorbitan monostearate, monodiglycerides, and DATAE esters were studied. During the temp. (aging) and heating cycles, the fully hydrogenated canola oil is transformed from its $\alpha$- and $\beta$'-forms to the $\beta$-form. The presence of 5 wt% surfactant will retard such transition and mostly $\beta$'- and $\alpha$-forms will be stabilized. The partially hydrogenated oil (IV = 3-69) shows the existence of different low and high m.p. forms. The low melting forms will transform into high melting forms at much lower rates of transition in the presence of those emulsifiers than in their absence. [on SciFinder(R)]