R. O. Feuge

Preparation of sucrose esters by interesterification

Reactions between sucrose and esters of long chain fatty acids customarily have been conducted in a mutual solvent, such as dimethylformamide. The solvent-free interesterification of molten sucrose and fatty acid esters at temperatures between 170–187 C has now been performed with the aid of lithium, sodium and potassium soaps as catalysts and solubilizers. When the reactants were heated rapidly and then subjected to reduced pressure, the interesterifications could be brought to equilibrium in 12 min or less, including the time necessary to melt the sucrose. The several soaps and combinations of soaps employed differed markedly in their performance. No sucrose esters were obtained with lithium palmitate, while the yield with lithium oleate was among the best, but consisted of over 90% tetra- and higher esters of sucrose. Lower esters were best produced with combinations of lithium oleate with sodium or potassium oleate employed at a level of about 25% total soaps, based on the weight of sucrose. The type of fatty acid ester employed also markedly affected the yield of sucrose esters. Among the esters tested, methyl carbitol palmitate (which could be formed in situ), monopalmitin, distearin and technical grade diglycerides (48% diglycerides) prepared from completely hydrogenated cottonseed oil, interesterified readily.

Polymorphic changes in mixtures of confectionery fats

The polymorphic behavior of mixtures of cocoa butter and high melting cocoa butter fraction with three types of confectionery fats and mixtures of the confectionery fats with each other were investigated with a differential scanning calorimeter. The confectionery fats were an interesterified-fractionated fat, a hydrogenated-fractionated fat, and a lauric acid fat. The lowered melting point observed in mixtures of confectionery fats with cocoa butter or cocoa butter fraction was related to the proportion of triglycerides dissimilar to the major components in cocoa butter and cocoa butter fraction contained in a particular confectionery fat. The hydrogenated-fractionated fat contained ca. two-thirds 2-oleodisaturated triglycerides similar to the major components of cocoa butter; the interesterified-fractionated fat, ca. one-third 2-oleodisaturated triglycerides. The lauric acid fat contained virtually no triglycerides similar to cocoa butter. The series of mixtures of confectionery fats with cocoa butter and cocoa butter fraction that had the least melting point lowering were those that contained 25% hydrogenated-fractionated fat; the ones that had the greatest lowering of melting point were those that contained 25% lauric acid fat. Mixtures of confectionery fats with cocoa butter possessed considerable amounts of low melting components, whereas similar mixtures with cocoa butter fraction exhibited a narrower melting range and possessed few low melting components. The more highly crystalline confectionery fats can accommodate the addition of fats containing some low melting components. The most compatible of the series of mixtures of confectionery fats with each other was the mixture of interesterified-fractionated fat containing 25% hydrogenated fractionated fat; the least compatible, hydrogenated fractionated fat containing 25% lauric acid fat.

Effect of liquid fat on melting point and polymorphic behavior of cocoa butter and a cocoa butter fraction

The polymorphic behavior of cocoa butter and a high-melting fraction of cocoa butter (CBF) was investigated by differential scanning calorimetry. The effect of liquid fat on melting point and polymorphic behavior was established for six mixtures: 83.5% cocoa butter and 16.5% of a low-melting fraction of cocoa butter (CBF-LM), 90% cocoa butter and 10% olive oil, and four mixtures of CBF and olive oil containing 10%, 20%, 30%, and 50% olive oil. Six polymorphs were found for cocoa butter and at least five for CBF. The melting points for cocoa butter and CBF were 35 and 38 C, respectively. Addition of CBF-LM to cocoa butter reduced the observable polymorphs to four and the melting point to 32.5 C. In cocoa butter, 10% olive oil reduced the observable polymorphs to three and the melting point to 31.5C. Similarly, 10% olive oil in CBF reduced the observable polymorphs to three and the melting point to 37 C. Amounts of 20%, 30%, and 50% olive oil in CBF reduced the polymorphs to two and the final melting point to 34.5, 33, and 32 C, respectively. Possible explanations for the observed polymorphic behavior are advanced. Changes in the rates of tempering of cocoa butter and CBF on addition of various amounts of liquid fat are discussed.

Quantitative estimation of sucrose esters of plamitic acid

Thin layer chromatography was adapted for direct quantitative estimation of sucrose esters of palmitic acid. Urea-phosphoric acid spray was used to detect the sucrose moiety of the various esters. The photometrically metermined density density of each spot on the thin layer plate was found to be proportional to its sucrose content. Ester content was then obtained by multiplying sucrose found by the factor, mol. wt. ester/mol. wt. sucrose. Ester mixtures were prepared by interesterifying sucrose with various proportions of methyl palmitate in dimethylformamide solution. Positional isomers were observed at each level of substitution but could not be adequately separated from each other for quantitative evaluation.

Variables affecting the yield of normal oleic acid produced by the catalytic hydrogenation of cottonseed and peanut oils

Summary1. The effects of the following factors have been investigated in the hydrogenation of cottonseed and peanut oils: temperature, concentration of catalyst, pressure of the hydrogen, degree of agitation, and nature of the nickel catalyst.2. The formation of stearic acid was found to be repressed and the formation of “iso-oleic” acid simultaneously favored by increasing the temperature, increasing the catalyst concentration, decreasing the pressure, and decreasing the agitation.3. The nature of the nickel catalyst, as influenced by its method of preparation, may have a large effect on the composition of the hydrogenated product. One of the nickel catalysts investigated formed excessive amounts of iso-oleic acid without being correspondingly selective.4. In the hydrogenation of cottonseed oil, within a comparatively wide range of conditions, the production of total solid acids with a given catalyst is relatively constant, since the conditions leading to the formation of stearic and iso-oleic acid are mutually exclusive. Extremes in either direction, however, lead to the production of excessive amounts of total solid acids.5. Peanut oil is a more suitable raw material than cottonseed oil for the production of normal oleic acid, because of its initially greater content of this constituent and its lesser content of linoleic acid.6. On the assumption that a quantitative separation could be made of the liquid acids from the solid acid fraction (saturated and iso-oleic) of the hydrogenated products, leaving minor amounts of unhydrogenated linoleic acid as an impurity in the separated normal oleic acid, the following maximum yields of “impure normal oleic acid” could be obtained: from cottonseed oil, 56 per cent of oleic acid of 85 per cent purity, 53 per cent of oleic acid of 90 per cent purity, and 48 per cent of oleic acid of 95 per cent purity; and from peanut oil, 70 per cent of oleic acid of 85 per cent purity, 68 per cent of oleic acid of 90 per cent purity, and 66 per cent of oleic acid of 95 per cent purity.

Influence of solvent on degree of acylation in the formation of sucrose esters

Sucrose palmitates were prepared by the interesterification of sucrose and methyl palmitate in different solvents. The ratio of methyl palmitate to sucrose in dimethylformamide (DMF) solution was varied so that the effect on yield and ester composition could be evaluated. When sucrose esters were prepared in DMF, the palmitoyl groups approximated a random distribution when only penta- and lower esters were formed. When the proportion of palmitoyl groups was increased, hexa- through octaesters were formed, but the yield was less than that calculated for a random distribution. The interesterification of sucrose and methyl palmitate in solvents other than DMF, but under otherwise identical reaction conditions, yielded different reaction products. Only traces of sucrose esters were produced in hexamethylphosphoramide and formylmorpholine. Reactions in dimethylsulfoxide and N-methyl-2-pyrrolidinone yielded larger percentages of higher esters than were obtained in DMF. However the distribution was far from random.

Properties of 2-oleodipalmitin, 2-elaidodipalmitin and some of their mixtures

The glycerides 2-oleodipalmitin (POP) and 2-elaidodipalmitin (PEP) were synthesized and their melting behavior and dilatometric properties were determined. Three mixtures of POP with PEP were examined. Five polymorphs of POP and four of PEP were identified by x-ray diffraction patterns. Rates of transformation of the lower melting polymorphs were, in general, quite rapid at temperatures just below their melting points. But transformation of unseeded POP to its highest melting form was slow and required several days at a temperature just below melting. Coefficients of expansion were determined for the highest melting polymorph and the liquid form of each triglyceride. Melting dilation was determined for the highest melting polymorph. Mixtures of POP with PEP exhibited different melting ranges depending on the tempering procedures and the composition, but even quickly-solidified mixtures tempered without melting to the highest melting range as they were slowly heated over a period of 2 hr. Slow cooling from the melt essentially segregated the components.

Thermal properties of 2-Oleodipalmitin and 2-Elaidodipalmitin and some of their mixtures

The polymorphism of 2-oleodipalmitin (POP), 2-elaidodipalmitin (PEP), and five of their mixtures was investigated by differential scanning calorimetry (DSC). The heat of fusion (ΔHf), heat of crystallization (ΔHc), and heat of transition (ΔHt) were determined. Rapid conversion to higher polymorphs, partial melting during conversion, and the overlapping of polymorphic forms precluded accurate determination of some caloric values. Four of five previously identified polymorphs of POP and all four polymorphs of PEP were identified by DSC. Five POP: PEP mixtures containing 8, 16, 25, 50, and 75% PEP, respectively, were examined. The presence of PEP in POP increased the stability of the lower POP polymorphs and, in concentrations as low as 8%, also increased the conversion rate of the higher POP polymorphs. In these heating curves, POP forms 5, 4, and 3, and a higher melting fraction that consisted of higher polymorphs of POP, polymorphs of PEP, and probably mixed crystals were evident. The ΔHf values for the tempered mixtures are lower, and the ΔHc values for the mixtures are higher than the calculated values. Heating and cooling curves and calorimetric data tables for POP, PEP, and their five mixtures are included.

Effect of 2-oleodipalmitin and 2-elaidodipalmitin on polymorphic behavior of cocoa butter

The polymorphic behavior of cocoa butter mixed with 2-oleodipalmitin (POP) or 2-elaidodipalmitin (PEP) was investigated with a differential scanning calorimeter. Six mixtures of cocoa butter containing 10, 25, and 50% POP and 10, 25, and 50% PEP were used. Each of the three cocoa butter-POP mixtures exhibited at least four polymorphic forms. The lowmelting form was obtained by quick chilling; the intermediate, by tempering for several hours just below the melting range; and the high-melting, by raising the temperature slowly to 25 C then holding there overnight or longer. In the cocoa butter-POP mixtures, only the low-melting form appeared to be more stable than the corresponding form for pure POP or cocoa butter. In addition to increased stability of the unstable low form, the rate of conversion from the intermediate to the high form, normally quite slow, increased in the cocoa butter-POP mixtures. Typical melting point lowering occurred when POP was added. POP was quite compatible with cocoa butter, the tempered mixture melting as a single compound; and the melting curves were fairly sharp. The three cocoa butter-PEP mixtures appeared to be incompatible. The cocoa butter and PEP behaved like a mixture of two fats, each of which melted independently.

Titration of cyclopropene esters with hydrogen bromide

Esters of the naturally occurring cyclopropene acids have heretofore been determined by titration with hydrogen bromide in glacial acetic acid. However, highly purified cyclopropenes had an apparent purity of only 83–86% by this method. The catalyzed addition of acetic acid during the titration has been shown to occur. Substituting toluene for the acetic acid not only gives the correct cyclopropene content, but also sharpens the end point of the titration. The new titration is performed at 70–75 C and 1,3-diphenylguanidine, which is soluble in toluene, should be used as a primary standard. The indicator solution is 0.03% crystal violet in butyric acid. Mono- and diglycerides and oxidized fatty compounds must be removed before titration. Oxirane oxygen can be determined by the new procedure, probably with an accuracy greater than that possible with hydrogen bromide in glacial acetic acid.