Studies in Interesterification II: Nutritional Quality of Directed Interesterified Cottonseed Oil

The plastic fat prepared from cottonseed oil by directed interesterification reaction was not only nutritionally equivalent to conventional hydrogenated edible fat ?Vanaspati”? but somewhat better in as much as it lowered the cholesterol level in serum.     

Influence of the position of unsaturated fatty acid esterified glycerol on the oxidation rate of triglyceride

The influence of the position of unsaturated fatty acid esterified glycerol on the oxidation rate of triglyceride was investigated at 50 C. Randomized triglycerides used were prepared by random interesterification between saturated and unsaturated monoacid triglycerides using sodium methoxide as catalyst. The monoacid triglycerides used were tripalmitin, tristearin, triolein and trilinolein. The molecular species of the randomized triglycerides were analyzed by high performance liquid chromatography (HPLC) in combination with gas liquid chromatography (GLC) and enzymatic hydrolysis. From the results of oxygen absorption measurement by GLC, the randomized triglycerides were more stable towards oxidation than the triglyceride mixtures which were prepared by mixing the equivalent quantities of the same monoacid triglycerides as used in the random interesterification. This may be due to the decrease in the contents of most unstable unsaturated monoacid triglycerides by random interesterification with saturated monoacid triglycerides. Furthermore, from the results obtained with the detailed analysis of the randomized triglycerides at different stages of oxidation, it became clear that the triglycerides having unsaturated fatty acids linked at the 2-position of glycerol are more stable towards oxidation than those linked at the 1(or 3)-position. The carbon chain length of saturated fatty acids has essentially no influence on the oxidation rates of unsaturated fatty acids esterified in the same glycerol.     

Studies in the Solvent Interesterification of Acidolysed Cottonseed Oil

The directed rearrangement reaction of an acidolysed cottonseed oil (acidolysed with palmitic acid) in solvent has been studied to find out the mode of distribution of the acyl radicals in the triglyceride moiety and also the changes in glyceride pattern and configuration of the oil after such reaction using pancreatic lipase hydrolysis. The glyceride compositions as calculated by the application of 1,3-random 2-random distribution hypothesis, of M. H. Coleman and W. C. Fulton of acidolysed cottonseed oil before and after directed interesterification reaction point out remarkable changes in the pattern of glycerides namely a notable increase of trisaturated glycerides with the diminution in the content of triunsaturated glycerides. Solid fat indices as determined by measuring the dilatation of fat, content of trisaturated glycerides and moderate slip points of the order of 37°C denote the suitability of using the modified fat thus produced as a good margarine base fat as the said fat has been shown to have a fairly long and extended plastic range as evidenced by low slopes in dilatometric charts compared to other conventional plastic fats.     

Solvent Interesterification of Vegetable Oils III

Directed interesterification reaction in solvents of cottonseed, peanut and cottonseed containing peanut, sesame and safflower oils was investigated with special reference to the influence of amount of sodium methoxide catalyst, oil content in solvent, temperature during the reaction and the nature of solvent on the characteristics of the reaction. The parameters were first studied with cottonseed oil and the conditions that favoured the reaction were adopted for peanut oil and cottonseed oil mixtures.     

Modification of Fats by Lipase Interesterification II: Effect on Crystallization Behaviour and Functional Properties

The crystallization behaviour and rheological properties of various preparations of cottonseed oil interesterified with fully hydrogenated soybean oil by lipases were studied. Variations related to the specificity of the lipase reaction were observed. The most striking effect was an increase in the relative stability of the β'-crystal form by interesterification, indicating possibilities for margarine production without trans fatty acids.     

The relationship of polymorphism to the texture of margarine containing soybean and cottonseed oils

Summary A correlation of the organoleptic and physical properties of hydrogenated soybean oil, blends of this oil with hydrogenated cottonseed oil, and their corresponding margarines has been made by comparing samples crystallized under tempered and essentially untempered conditions. Margarine, which is usually processed under the latter condition and which contains a high percentage of hydrogenated soybean oil, will at times show a strong tendency to develop grain. This graininess was characterized by the presence of high meltingbeta polymorphs, formed by a slow rate of crystal growth. Thus the difference in the polymorphic behavior of highly hydrogenated cottonseed and soybean oil observed by Bailey still prevails in the partially hydrogenated oils but to a lesser extent. The tendency for hydrogenated soybean oil to formbeta crystals can be reduced or eliminated by conditions which promote faster crystal growth and/or the incorporation ofbeta prime stable triglycerides, which control crystal growth through mixed crystal or solid solution formation.     

Interesterification of edible oils

Types of interesterification discussed are (a) interchange between a fat and free fatty acids, in which the most important reaction is the introduction of acids of low mol wt into a fat with higher fatty acids; (b) interchange between a fat and an alcohol, e.g., with glycerol, in order to produce emulsifiers like monoglycerides; (c) rearrangement of fatty acid radicals in triglycerides, the so-called transesterification which in recent years has taken on the same importance as hydrogenation or fractionation. In natural fats, the fatty acid radicals are not usually randomly distributed but become so by rearrangement; the distinctive physical properties of natural fats and oils can be changed within limits by this transesterification. Well-known examples are cocoa butter, palm oil, and lard. More important is the transesterification of a mixture of different fats and oils; e.g., the combination of hydrogenation and interesterification allows the production of a solid fat with high linoleic acid content. The composition of glycerides after random interesterification can be calculated by formulas. Distinct from random is such directed interesterification. This is done by working at low temperatures that glycerides with higher melting point crystallize from the reaction mixture. Directed interesterification can be combined with fractionation, for instance, to get a higher yield of liquid fraction from palm oil than is obtained by fractionation alone. The transesterification process can be performed in a batch or continuously. A small amount of metallic sodium or sodium ethylate is used as catalyst, which is destroyed by water or acid and removed after the reaction.     

Modification of Fats by Lipase Interesterification I: Changes in Glyceride Structure

Blends of refined cottonseed oil and fully hydrogenated soybean oil were subjected to interesterification reactions catalyzed by Rhizomucor miehei and Candida antartica lipases in a solvent free system. The interesterification decreased the levels of triunsaturated and trisaturated triglycerides and increased the amounts of mono- and disaturated triglycerides in the blends. The triglyceride products obtained by the two enzyme preparations were similar in composition but differed in the proportions: levels of high melting glycerides were higher in the products obtained with C. antartica lipase. The amounts of hydrolysis products formed depended on both the choice of enzyme and the substrate composition. The content of 1,3-diglycerides formed exceeded that of 1,2-diglycerides and low levels of monoglycerides were formed during the reactions.     

Preparation and Characterization of a Zero-trans Margarine

Two new types of margarines were prepared in this study. The first was processed without the traditional milk flavour. The fat phase consists of 40% partially hydrogenated cottonseed oil (m. p. 42.2°C), 40 % cottonseed oil and 20 % olive oil as a source of flavouring and antioxidant materials. The second margarine was based mainly on the interesterified fat formed from lipase interesterification of a mixture of 86.5 % cottonseed oil and 13.5 % fully hydrogenated soybean oil (m. p. 67.2°C). Characterization and evaluation of these new types of margarines in relation to two conventional margarines are reported. The presence of diglycerides in the interesterified fat (free from trans isomers) reduced the amount of crystallized solids and the properties of the product were very close to conventional soft margarines. Margarine with olive oil taste was well accepted.     

Beschleunigung der gelenkten Umesterung mittels periodischer,variabler Temperaturführung

Acceleration of the Directed Interesterification of Oils by Periodic Variation of the Reaction Temperature By means of directed interesterification the solid phase content in an oil can be increased without affecting the physiologically important linoleic acid. However, the directed interesterification of highly unsaturated oils proceeds very slowly. Calculations with a mathematical model demonstrate that the directed interesterification can be accelerated considerably, by periodically decreasing the reaction temperature for a short period. This procedure applied on laboratory scale to the directed interesterification of e. g. sunflowerseed oil and lard accelerated the reaction by approximately a factor of 3. Further it appeared to be possible to prepare a margarine of which the fat phase had been composed entirely of directed inter-esterified sunflowerseed oil.     

Margarine and shortening oils by interesterification of liquid and trisaturated triglycerides

Liquid vegetable oils (VO), including cottonseed, peanut, soybean, corn, and canola, were randomly interesterified with completely hydrogenated soybean or cottonseed hardstocks (vegetable oil trisaturate; VOTS) in ratios of four parts VO and one part VOTS. Analysis of the reaction products by high-performance liquid chromatography showed that at 70°C and vigorous agitation, with 0.5% sodium methoxide catalyst, the reactions were complete after 15 min. Solid-fat index (SFI) measurements made at 50, 70, 80, 92, and 104°F, along with drop melting points, indicated that the interesterified fats possess plasticity curves in the range of commercial soft tub margarine oils prepared by blending hydrogenated stocks. Shortening basestocks were prepared by randomly interesterifying palm or soybean oil with VOTS in ratios of 1:1 or 3:1 or 4:1, respectively. Blending of the interesterified basestocks with additional liquid VO yielded products having SFI curves very similar to commercial all purpose-type shortening oils made by blending hydrogenated stocks. Other studies show that fluid-type shortening oils can be prepared through blending of interesterified basestocks with liquid VO. X-ray diffraction studies showed that the desirable β′ crystal structure is achieved through interesterification and blending. Presented at AOCS Annual Meeting & Expo, Atlanta, Georgia, May 8–12, 1994.     

Estimation of heat of combustion of triglycerides and fatty acid methyl esters

Equations were developed for the estimation of gross heat of combustion (HG) of triglycerides (TGs) and fatty acid methyl esters (FAMEs) from their saponification number (SN) and iodine value (IV). HG of TG=1,896,000/SN − 0.6 IV — 1600 and HG of FAME=618,000/SN − 0.08 IV — 430. When these equations were tested on cottonseed oil, soybean oil, partially hydrogenated soybean oil, peanut oil, sunflower oil, sunflower oil methyl esters, soybean oil methyl esters and cottonseed oil methyl esters, predicted HG values agreed well with those reported in the literature.     

Enzymatic interesterification of olive oil with fully hydrogenated palm oil: Characterization of fats

Seven different reaction products were prepared via enzymatic interesterification of extra‐virgin olive oil (EVOO) and fully hydrogenated palm oil (FHPO), by varying the initial weight ratio of EVOO to FHPO from 80 : 20 to 20 : 80. The chemical, physical and functional properties of both the semi‐solid reaction products and the corresponding physical blends of the precursor starting materials were characterized. Fats prepared using large proportions of FHPO contained high levels of TAG species containing only saturated fatty acid residues. By contrast, high levels of TAG species containing both saturated and unsaturated fatty acid residues were found in fat products obtained with the lowest proportions of FHPO. Independently of the initial weight ratio of EVOO to FHPO, the interesterified products were characterized by a higher molar ratio of unsaturated to saturated fatty acid residues at the sn‐2 position, were softer over a wide temperature range, exhibited lower oxidative stabilities and were completely melted at lower temperatures than the corresponding physical blends. Potential applications of the reaction products range from margarines (highest weight ratios of EVOO to FHPO) to frying fats (lowest weight ratios of EVOO to FHPO).     

Plastic fats with zero trans fatty acids by interesterification of mango,mahua and palm oils

Speciality plastic fats with no trans fatty acids suitable for use in bakery and as vanaspati are prepared by interesterification of blends of palm hard fraction (PSt) with mahua and mango fats at various proportions. It was found that the interesterified samples did not show significant differences in solid fat content (SFC) after 0.5 or 1 h reaction time. The blends containing PSt/mahua (1:1) showed three distinct endotherms, indicating a heterogeneity of triacylglycerols (TG), the proportions of which altered after interesterification. The SFC also showed improved plasticity after interesterification. Similar results were observed with other blends of PSt/mahua (1:2). These changes in melting behavior are due to alterations in TG composition, as the trisaturated‐type TG were reduced and the low‐melting TG increased after interesterification. The blends containing PSt/mango (1:1) showed improvement in plasticity after interesterification, whereas those containing PSt/mango (2:1) were hard and showed high solid contents at higher temperature and hence may not be suitable for bakery or as vanaspati. The blends with palm and mahua oils were softer and may be suitable for margarine‐type products. The results showed that the blends of PSt/mahua (1:1, 1:2) and PSt/mango (1:1) after interesterification for 1 h at 80 °C showed an SFC similar to those of commercial hydrogenated bakery shortenings and vanaspati. Hence, they could be used in these applications in place of hydrogenated fats as they are free from trans acids, which are reported to be risk factors involved in coronary heart disease. For softer consistency like margarine applications, the blends containing palm oil and mahua oil are suitable.     

Effect of Interesterified Fats and Isolated trans Fatty Acids on Serum Lipid Classes in Cholesterol-Bile Salt Stressed Rats

Interesterified plastic fat products based on a) sal fat and groundnut oil (30: 70, w/w;P/S,0.8) (sal-GNO);b) vanaspati, partially hydrogenated vegetable oil and groundnut oil (40:60; P/S, 1.0; isolated trans fatty acid content 17%) (vanaspati-GNO);c) cottonseed oil (P/S, 1.5) (CSO) and d) sal fat and safflower oil (50:50, P/S, 1.3) (sal-saff) were prepared using dry sodium methoxide as the catalyst. The products had slip points of 33?34°C. These products, their original blends, safflower oil (P/S, 8.5) and a blend of vanaspati and safflower oil (50 : 50, P/S, 2.8 and isolated trans fatty acid content 22%) (vanaspati-saff) were tested for hypolipidaemic effect (serum total cholesterol, total lipids, triglycerides and phospholipids) in cholesterol-bile salt stressed rats. All the test fats having linoleic acid content varying from 21.9-76.6% and P/S ratio from 0.8 to 8.5 and fed at 10% level providing 23% calorie were found to be superior to vanaspati (P/S, 0.16, 3% linoleic, 43% isolated trans fatty acids). P/S ratio of 1.5 and linoleic content of 30% in fat were found to be optimum for maximum hypolipidaemic effect at above dietary regimen. Fat and cholesterol contents of liver of animals, fed test lipids were significantly lower than that of animals fed vanaspati. when linoleic acid content of the product was comparatively low (e.g. sal-GNO, 25%), the process of rearrangement reduced the cholesterol content of liver. With high linoleic acid content (CSO, 48.2% or sal-saff, 40.4%) interesterification was without any effect. Hypolipidaemic effect of interesterified products was similar to that observed with original materials. Thus, the above quality of a fat having characteristics within the above ranges does not depend upon the distribution of acyl groups in glyceride molecules. Isolated trans fatty acids behaved more or less like a saturated fatty acid in elevating serum lipids. Vanaspati was found to be highly hyperlipidaemic.     

Some additional notes on the kinetics and theory of fatty oil hydrogenation

1. Equations are given for estimating from the composition of oil samples the relative reaction rates of the different unsaturated fatty acids in an oil subjected to catalytic hydrogenation.
2. Application of the equations to data from the hydrogenation of cottonseed oil reveals that the ratio of reaction rates, linoleic acid to oleic acid, varies from about 4 to 1 in very non-selective to about 50 to 1 in very selective hydrogenation. Re-examination of analytical data on two series of linseed oils hydrogenated selectively and non-selectively showed the following relative reaction rates for oleic, isolinoleic (9: 10, 15: 16 octadecadienoic), linoleic, and linolenic acids, respectively: non-selective, 1, 2.5, 7.5, 12.5; selective, 1, 3.85, 31, 77. In the non-selective hydrogenation of the oil, 24% of the linolenic acid reacting went to linoleic acid, 65% to isolinoleic acid, and 11% directly to oleic acid. In the selective reaction the corresponding figures were none to linoleic acid, 54% to isolinoleic acid, and 46% to oleic acid. The behavior of soybean oil hydrogenated selectively was quite similar to that of linseed oil.
3. The results are discussed in relation to the theory of catalytic hydrogenation. They indicate that the solution of hydrogen in the oil and the adsorption of unsaturated oil on the catalyst are the two steps which are controlling with respect to the reaction rate. It is suggested that the hydrogen pressure, the degree of hydrogen dispersion through the oil, the catalyst concentration, and the temperature all affect the selectivity of the reaction through their influence on the concentration of hydrogen in the reaction zone, with selectivity being favored by a low concentration.

     

Chemical and enzymatic interesterification of tristearin/ triolein-rich blends: Chemical composition,solid fat content and thermal properties

Blends of high-oleic sunflower oil and fully hydrogenated canola oil were subjected to enzymatic and chemical interesterification using Candida antarctica lipase (5%) and sodium methoxide (0.3%), respectively. The effect of each interesterification process was determined by comparing the triacylglycerol (TAG) composition, solid fat content (SFC) profiles and thermal properties of the blends before and after interesterification. Interesterification resulted in a decrease in the concentration of triunsaturated and trisaturated TAG and an increase in the proportion of mono- and disaturated TAG. These alterations in TAG composition and the presence of a greater variety of TAG species upon interesterification was correlated with a broader melting transition by differential scanning calorimetry and, ultimately, a lower melting point for the interesterified blends. Much broader ranges in plasticity were observed for the interesterified blends (chemically and enzymatically) compared to the physical blends. Even though ideal solubility of stearin in oil was observed, the value predicted by the Hildebrand model was higher than the actual amount. Crystallization kinetic parameters (Avrami index and rate constant) were similar for the non-interesterified, enzymatically interesterified and chemically interesterified blends when compared as a function of SFC. Results from this work will aid in the formulation of more healthy fat and oil products and address a critical industrial demand in terms of formulation options for spreads, margarines and shortenings.     

Modification of vegetable oils. XIV. Properties of aceto-oleins

Summary Pure 1,2-diaceto-3-olein was prepared by acetylating mono-olein. A mixture of aceto-oleins was prepared by acetylating a mixture of mono-, di-, and trioleins derived from commercial oleic acid. Several natural oils were acetylated either by ester-ester interchange with triacetin or by glycerolysis followed by acetylation. The various products were examined for cloud and solid points, point of complete melting, and consistency. The 1,2-diaceto-3-olein, which contains 19.5% of acetyl group on a weight basis, has a melting point of −18.3°C. while the mixture of aceto-oleins, which contained 14.3% of acetyl on a weight basis, melted at −24°C. Acetylation of the natural oils raises in most instances their cloud and solid points and point of complete melting, but it also greatly increases their plasticity at lower temperatures. Aceto-compounds were used to plasticize highly hydrogenated cottonseed oil. These mixtures were prepared so that they possessed the consistency of margarine oil at room temperature. These mixtures, when compared with partially hydrogenated oil, butterfat, or a mixture of cottonseed oil and hydrogenated cottonseed oil, were softer below room temperature and firmer above room temperature. A margarine-like product containing 79% of aceto-olein and 18.5% of highly hydrogenated cottonseed oil had a practically constant consistency over the temperature range of −15° to 49°C. (5° to 120°F.). Presented at the 26th Fall Meeting of the American Oil Chemists' Society, Cincinnati, O., Oct. 20–22, 1952. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Changes in the characteristics and composition of oils during deep-fat frying

Refined, bleached, and deodorized soybean oil and vanaspati (partially hydrogenated vegetable oil blend consisting of peanut, cottonseed, nigerseed, palm, rapeseed, mustard, rice bran, soybean, sunflower, corn, safflower, sesame oil, etc., in varying proportions) were used for deep-fat frying potato chips at 170, 180, and 190°C. Refractive index, specific gravity, color, viscosity, saponification value, and free fatty acids of soybean oil increased with frying temperature, whereas the iodine value decreased. The same trend was observed in vanaspati, but less markedly than in soybean oil, indicating a lesser degree of deterioration. Iodine values of soybean oil and vanaspati decreased from their initial values of 129.8 and 74.7 to 96.2 and 59.6, respectively, after 70 h of frying. Polyunsaturated fatty acids decreased in direct proportion to frying time and temperature. Losses were highest in soybean oil with a 79% decrease in trienoic acids and a 60% decrease in dienoic acids. Levels of nonurea adduct-forming esters were proportional to the losses of unsaturated fatty acids. Butylated hydroxyanisole and tertiary butylhydroquinone did not affect deterioration of soybean oil at frying temperatures.     

Stability of Interesterified Fats

Stability study carried out with interesterified (i) refined cottonseed oil (CSO), blends of (ii) vanaspati and refined groundnut oil (40:60 w/w) (vanaspati-GNO), (iii) refined and bleached sal (Shorea robusta) fat and refined groundnut oil (30:70) (Sal-GNO) and (iv) edible grade sheep tallow and refined groundnut oil (30:70) (ST-GNO) indicated that rearranged CSO and ST-GNO were more and sal-GNO less prone to oxidative rancidity compared to their corresponding starting stocks. Vanaspati-GNO was more or less similar to its starting stock. In other words, the process of interesterification had different effects on different starting stocks vis-à-vis oxidative rancidity. Addition of antioxidant (BHA) improved the stability of interesterified products to a large extent. Development of oxidative rancidity as measured by peroxide value in all the interesterified products during storage was faster than that observed with vanaspati. All the interesterified products were stable towards hydrolytic rancidity during storage. When the linoleic content of a blend was about 25%, the process of interesterification had no or marginal adverse effect on the development of oxidative rancidity. Higher linoleic acid (about 50%) made the stock more unstable as a result of interesterification. Comparatively more instability of interesterified blend containing sheep tallow cannot be explained on the basis of its linoleic acid content and its migration as a result of rearrangement.