LIPASE-CATALYZED ACIDOLYSIS OF CORN OIL WITH CONJUGATED LINOLEIC ACID IN HEXANE

Lipase-mediated acidolysis of corn oil with conjugated linoleic acid (CLA) was studied in hexane. The largest extent of incorporation was obtained using a weight ratio of CLA to corn oil of 1:7 (1:2.22 mole ratio). Commercial immobilized lipases from Rhizomucor miehei and Candida antarctica effectively catalyzed interesterification. Of the total acylglycerols in the products, triacylglycerols constituted >90%. For both immobilized enzymes, CLA residues were esterified mainly at the sn-1,3 positions.     

Biocatalyzed acidolysis of olive oil triacylglycerols with 9c,11t and 10t,12c isomers of conjugated linoleic acid

Lipase catalyzed acidolysis of triacylglycerols (TAG) of olive oil with 9c,11t and 10t,12c isomers of conjugated linoleic acid (CLA) in an organic solvent was studied. The CLA isomers were first obtained in good yield starting from sunflower oil. The acidolysis reactions were carried out with two immobilized lipase, an sn-1,3-regiospecific one from Rhizomucor miehei and a nonregiospecific one from Candida antartica, in order to valuate not only the total incorporation of CLA isomers in olive TAG but also the distribution of the cited isomers in the three sn positions of TAG molecules. The effect of reaction time was also investigated; in fact two series of reactions, with the two lipases, were carried out for 24, 48 and 72 h. The TAG fractions relative to the starting olive oil TAG (OOTAG) and to the samples obtained from the acidolysis reactions were analyzed to obtain the total and positional fatty acid percentage compositions. The results show that after 24 h of reaction, high levels of CLA isomers were incorporated in OOTAG using Lipozyme IM and that slightly higher values were obtained by increasing the reaction time; Novozym 435 was less effective in catalyzing the incorporation of CLA isomers and CLA isomers were incorporated in OOTAG to a lesser degree. The results of stereospecific analysis of TAG fractions showed that, at every reaction time, the CLA isomers were incorporated mainly in sn-1 and sn-3 positions, as expected on the basis of the enzyme regiospecificity. As regards the TAG sn-2 position, the incorporation of CLA isomers was not observed after 24 h, but after 48 and 72 h; this occurrence was probably due to isomerization phenomena or regiospecificity loss after extended reaction times.     

Chemoenzymatic synthesis of structured triacylglycerols with conjugated linoleic acids (CLA) in central position

A chemoenzymatic process for the production of structured triacylglycerols (TAG) containing CLA at sn2 position and lauric acid at external ones is proposed. First, castor bean oil was chemically dehydrated and isomerised to obtain a new modified oil with very high proportion of CLA (>95%). Then, this new oil was used for enzymatic transesterification allowing the grafting of lauric acid at external positions of the TAG backbone by using 1,3 regioselective enzymes. Among these, Aspergillus niger lipase was not satisfactory giving very low lauroyl incorporation (<5%) On the contrary, lipases from Thermomyces lanuginosa (Lipozyme TL IM) and from Carica papaya latex allowed good reaction yields. The effect of the type of acyl donor was studied. With alkyl esters T. lanuginosa lipase provided a final incorporation of 58.9% after 72 h corresponding to 88.4% transesterification yield. Concerning C. papaya lipase, incorporation of lauroyl residues was lower than Lipozyme TL IM. This lipase exhibited higher performance with lauric acid accounting for 44.7% lauroyl incorporation at the end of reaction for a 67.1% transesterification yield. The effect of the substrates mole ratio was also evaluated. It was observed that a 1:3 TAG/acyl donor mole ratio was the most efficient for both lipases. Finally, fatty acids regiodistribution of the newly formed structured TAG was determined. With Lipozyme TL IM, the proportion of lauric acid incorporated at the sn2 position did not exceed 5.4% after 72 h while with C. papaya lipase a more pronounced incorporation of lauroyl residues at the central position (8.8%) was observed.     

LIPASE-CATALYZED MODIFICATION OF SESAME OIL TO INCORPORATE CAPRIC ACID

Sesame oil was modified to incorporate capric acids (C10:0) with an immobilized lipase, IM60, from Rhizomucor miehei . Transesterification was performed with and without organic solvent. After 24 h incubation in hexane, there was an average of 28.3±3.5 mol% incorporation of C10:0 into sesame oil. The solvent-free reaction produced an average of 25.7p±4.3 mol% capric acid. As enzyme load, substrate mole ratio, and incubation time increased, mol% capric acid incorporation also increased. For the time course reaction, incorporation of C10:0 increased up to 34.3 and 25.3 mol%, at 72 h and 8 h, for the hexane and solvent-free reactions, respectively. The highest C10:0 incorporation (62.2 mol%) occurred at a mole ratio of 1:7 (sesame oil/C10:0) in hexane and for the solventfree reaction (35.7 mol%) was obtained at a mole ratio of 1:5 and 1:7. At a lipase load of 15%, incorporation of C10:0 reached optimal values of 30.0 and 25.2 mol% for the reactions with and without hexane, respectively. There was a decline in mol% incorporation of C10:0 into sesame oil in hexane with the addition of increasing amounts of water ranging from 0–12%. With no added water, C10:0     

PREPARATION OF STRUCTURED LIPIDS WITH SPECIAL FUNCTIONAL PROPERTIES

Enzymatic acidolysis of rapeseed oil with capric acid was carried out to obtain structured lipids. The reaction was catalyzed by Lipozyme IM lipase from Rhizomucor miehei. The enzyme preparations contained 2.8 and 10% water. The reaction conditions were enzyme load of 8% (w/w total substrates), substrate mole ratio of 1:6 (rapeseed oil:capric acid), and reaction temperature of 65C. The results showed that triacylglycerols (TAG) after transesterification contained mainly oleic, linoleic and linolenic acids (about 90%) in the internal sn-2 position, whereas capric acid was mostly in the external sn-1,3 positions (approximately 40%). The quantity of water in the reaction medium had a significant influence on the yield and quality of the TAG fraction.     

Enzymatically Modified Beef Tallow as a Substitute for Cocoa Butter

ABSTRACT: Dark "chocolate" samples were formulated with either cocoa butter (CB), randomized tallow (RT) made with Candida antarctica (SP 435) lipase, or a beef tallow: stearic acid structured lipid (SL) made by acidolysis using Rhizomucor miehei (IM 60) lipase. Fatty acid composition, thermal profile, solid fat content (SFC), hardness, and polymorphic structure were determined for the fats and/or "chocolate" samples. An accelerated fat bloom study was performed on the "chocolate" samples. Neither of the modified tallows had a detrimental effect on the crystallization of CB after proper tempering of the "chocolates." RT did not soften the "chocolate" and both of the modified lipids reduced bloom rates.     

Physical properties of palm kernel olein-anhydrous milk fat mixtures transesterified using mycelium-bound lipase from Rhizomucor miehei

The transesterification activity of mycelium-bound lipase from Rhizomucor miehei on palm kernel olein:anhydrous milk fat (PKO:AMF) blends was investigated. Commercial immobilised R. miehei lipase preparation, Lipozyme IM60 (Novo Nordisk), was used as a comparison. Mixtures of PKO:AMF, at ratios of 100:0, 70:30, 60:40, 50:50 and 0:100, were transesterified using either enzyme in a solvent-free system. The triglyceride (TG) profile, slip melting point, solid fat content, melting thermogram and the polymorphic form of the unreacted and transesterified mixtures were evaluated. Results indicated that transesterification by either enzyme was able to produce an oil mixture with new TG profiles, generally lower slip melting points and solid fat contents. The melting thermograms from differential scanning calorimetry analysis indicated changes in the triglyceride's crystalline composition and an overall shift to lower melting TG. Although the catalytic activities were similar for both lipases, Lipozyme-catalysed mixtures produced higher degrees of transesterification (43–51%) than mycelium-bound lipase-catalysed (22–34%) mixtures. This study also demonstrated that the transesterified PKO:AMF mixture at 70:30 ratio completely melted at 25C, and this meets the melting criteria for fat used in ice cream formulation.     

Use of enzymatic transesterified palm stearin-sunflower oil blends in the preparation of table margarine formulation

Palm stearin–sunflower oil (PS:SO) blends, formulated by mixing 40 to 80% palm stearin in increments of 10% (w/w), were subjected to transesterification catalysed by lipases from Pseudomonas sp. and Rhizomucor miehei (Lipozyme 1M 60). The physical properties of the transesterified products were evaluated by slip melting point (SMP), differential scanning calorimetry (DSC), solid fat content (SFC) and X-ray difflaction (XRD) analyses. SMP results indicate that Pseudomonas lipase caused a bigger drop in SMP (33%) in the PS–SO (40:60) blend than the R. miehei-lipase-catalysed reaction blend (13%). The Pseudomonas-catalyzed blends of PS-SO, at 40:60 and 50:50 ratios, showed complete melting at 37 and 40°C, respectively, while the R. miehei-catalyzed PS–SO blend at 40:60 ratio had a residual SFC of 3.9% at 40°C. Pseudomonas lipase also successfully changed the polymorphic form(s) in the unreacted PS–SO mixture from a predominantly β form to a predominantly β′ form in the transesterified blends. However, no changes in polymorphic forms were observed after transesterification with R. miehei lipase (as against to the unreacted PS–SO blends). These results suggest that the Pseudomonas lipase caused a greater randomization and diversification of fatty acids, particularly palmitic acids, in palm stearin with the unsaturated fatty acids from sunflower oil than did R. miehei lipase. Based on the physical characteristics, the Pseudomonas-catalyzed 40:60 and 50:50 PS:SO blends would be the two most suitable blends to be used as table margarine formulations.     

Synthesis of Diacylglycerols Containing CLA by Lipase-Catalyzed Esterification

ABSTRACT:  Diacylglycerols (DAG) were prepared by esterification of glycerol with conjugated linoleic acid (CLA) in the presence of an immobilized 1,3-regiospecific lipase from Rhizomucor miehei and vacuum conditions. The effects of several parameters, namely, temperature, enzyme loading, stirring speed, and vacuum, on the concentration and the purity of the DAG were studied. The reaction temperature influenced both the reaction rate and the concentration of the DAG. The rate of DAG synthesis increased as the enzyme loading increased. However, for high enzyme loadings, the concentration of triacylglycerols (TAG) increased significantly at long reaction times and, as a result, the purity of the DAG decreased. When the stirring speed increased from 150 to 450 rpm, the DAG concentration increased significantly. However, at stirring speeds above 450 rpm, no significant increases in DAG concentration were observed. When the pressure was decreased from 20 to 3 mmHg, the maximum concentration of DAG increased from 76.0% to 80.5%. No increase in the DAG concentration was observed when the pressure was decreased from 3 to 1 mm Hg, even though a slightly higher DAG purity was achieved at 1 mm Hg. For the range of absolute pressures tested, the concentrations of 1,2-DAG were less than 1%.     

Lipase-catalyzed acidolysis of palm olein and caprylic acid in a continuous bench-scale packed bed bioreactor

Enzymatic acidolysis of refined, bleached and deodorized (RBD) palm olein with caprylic acid was carried out in a continuous packed bed bioreactor to produce structured lipid (SL) that can confer metabolic benefits when consumed. Lipozyme^® IM 60 from Rhizomucor miehei, a 1,3-specific lipase, was used as the biocatalyst in this study. After 24 h of reaction, 30.5% of the total fatty acid content of the modified oil was found to be caprylic acid, indicating its incorporation into the palm olein. The triacylglycerols (TAGs) of palm olein after acidolysis were separated and were characterized by seven clusters of TAG species with equivalent carbon number (ECN), C28, C30, C32, C34, C36, C38 and C40. Caprylic–oleic–caprylic TAGs were predicted in cluster C32, which recorded the highest amount, with 35.3% of the total TAG. Fatty acid composition at the sn-2 position was determined, by pancreatic lipolysis, as C8:0, 9.2%; C12:0, 2.3%; C14:0, 1.8%; C16:0, 21.3%; C18:0, 4.7%; C18:1, 60.7%. Iodine value (IV), slip melting point (SMP) and differential scanning calorimetric (DSC) analyses of SL were also performed. In IV analysis, SL recorded a drop of value from 60.4 to 48.2 while SMP was reduced from 13 to 4.2 °C, in comparison to RBD palm olein. DSC analysis of SL gave a melting profile with two low melting peaks of −15.97 and −11.78 °C and onset temperatures of −18.43 and −14.03 °C, respectively.     

Lipase catalyzed modification of fish oil to incorporate capric acid

Immobilized lipase, IM60, from Rhizomucor miehei, was used as a biocatalyst for the incorporation of capric acid (C10:0) into menhaden fish oil concentrate containing 34.7 mol% eicosapentaenoic acid (20:5n-3) and 34.4 mol% docosahexaenoic acid (22:6n-3). Transesterification (acidolysis) was performed in hexane and solvent-free media. Tocopherol content was analyzed before and after enzymatic modification. Products were analyzed by gas liquid chromatography. After 24 h incubation in hexane, there was an average of 31.1±4.6 mol% incorporation of C10:0 into fish oil, while 20:5 and 22:6 were reduced to 12.6±3.1 and 13.7±4.4, respectively. The solvent-free reaction produced an average of 28.8±4.7 mol% capric acid incorporation; 20:5 and 22:6 decreased to 16.1±5.7 and 13.5±3.0 mol%. The effect of incubation time, substrate mole ratio, enzyme load, and added water were also studied. Generally, as enzyme load, mole ratio, and incubation time increased, mol% capric acid incorporation also increased. Time course of reaction indicated that the highest C10:0 incorporation occurred at 72 h, for both the reaction in hexane (33.5 mol%) and the solvent-free reaction (36.0 mol%). The highest C10:0 incorporation for the substrate mole ratio reaction occurred at a mole ratio of 1:8 in hexane (50.7 mol%) and the solvent-free reaction (36.7 mol%). Although the highest C10:0 incorporation (31.8 and 48.6 mol%) occurred at an enzyme load of 15% in hexane and 20% for the solvent-free reaction respectively, the values were not significantly different (P<0.05) after 5% enzyme load. Mol% incorporation of C10:0 declined with increasing amounts of water. At 1% added water, high C10:0 incorporation was achieved for the reaction in hexane (39.3 mol%) and the solvent-free reaction (26.0 mol%). Pancreatic lipase catalyzed sn-2 positional analysis was performed on the fish oil before and after enzymatic modification. Fish oil containing capric acid was successfully produced and may be beneficial in certain food and nutritional applications.     

Enzymatic production of low‐calorie structured lipid from Echium seed oil and lauric acid: optimisation by response surface methodology

Low‐calorie structured lipids (SLs) were produced from Echium seed oil and lauric acid by enzymatic acidolysis reactions. Lipozyme^® RM IM, commercially immobilised sn‐1,3 specific lipase derived from Rhizomucor miehei, was used in the reactions. The effects of substrate molar ratio and reaction time on incorporation of lauric acid were investigated and optimised by response surface technology (RSM) with five‐level, two‐factor central composite design. Good quadratic model was obtained for the response [lauric acid (%) incorporation]. Highest lauric acid incorporation into Echium oil was obtained at 5:1 lauric acid/Echium oil molar ratio and at 4‐h reaction time. The model was verified at these conditions and furthermore scale‐up synthesis of SLs was performed. At these conditions, SL contained predominantly lauric acid (42.8%), oleic acid (9.9%), linoleic acid (10.8%), α‐linolenic acid (15.1%), γ‐linolenic acid (7.5%) and stearidonic acid (8.5%) with% 64.4 of PUFA at sn‐2 position in gram‐scale synthesis.     

Transesterification of conjugated linoleic acid and tricaprylin by lipases in organic solvents

Lipase-catalyzed transesterification of tricaprylin with conjugated linoleic acid (CLA) ethyl ester was performed to produce triacylglycerols containing conjugated linoleic acid. Six commercially available lipases, and seven solvents were screened for their ability to incorporate CLA into tricaprylin. The transesterification reaction was performed by incubating a 1:2 mole ratio of tricaprylin and CLA ethyl ester in 3 ml solvents at 55°C, and the products were analyzed by gas chromatography. Three lipases, Novozym 435, Lipozym IM and lipase PS-C were chosen to allow a comparison of transesterification activity in our model reaction. The highest CLA incorporation with Novozym 435 and Lipozym IM was achieved in hexane while isooctane produced the highest CLA incorporation with lipase PS-C. Lipase PS-C gave higher CLA incorporation into tricaprylin when fatty acid was used as the acyl donor than other lipases did. Lipozym IM and lipase PS-C had not restrict specificity to sn-1, 3 positions, even though they had high specificity at sn-1, 3 positions. Novozym 435 among lipases tested was the most effective on the incorporation of CLA into tricaprylin.     

Interesterification (acidolysis) of butterfat with conjugated linoleic acid in a batch reactor

Six commercial lipases, in free or immobilized form, were tested for their ability to catalyze acyl exchange between conjugated linoleic acid and anhydrous butterfat under solvent-free conditions. Immobilized Candida antarctica lipase exhibited the best activity. Experiments were conducted for this lipase in butterfat to conjugated linoleic acid ratios of 10:1 (vol/vol), temperatures from 30 to 70 degrees C, enzyme concentrations of 50 to 200 mg/g of reaction mixture, and water contents of 0.15 to 2% (wt/wt). At the maximum enzyme concentration used, equilibrium was reached within the first 24 h of reaction. The optimum temperature was 50 degrees C. The triacylglycerol profile of the product butterfat reflected changes in the relative proportions of fatty acid residues as the reaction proceeded, with increases in those triacylglycerols containing 46 to 54 carbon atoms and concomitant decreases in those triacylglycerols containing 34 to 42 carbon atoms.     

Interpretation of triacylglycerol profiles of palm oil,palm kernel oil and their binary blends

The effects of lipase-catalyzed interesterification (IE) on changes in the chemical composition of palm oil (PO), palm kernel oil (PKO) and their binary blends at 3:1, 1:1 and 1:3 (w/w) ratios, using both 1,3 specific Rhizomucor miehei, (Lipozyme™) and non-specific Pseudomonas sp. lipases were evaluated. IE of the native PO and PKO showed very distinct chemical composition changes. Catalysis of PO, using both lipases, caused synthesis of more medium and long chain triacylglycerols (TAG), with MMM/OLL, MMP, OOO and PPP (M, myristic acid; O, oleic acid; L, linoleic acid; P, palmitic acid) increasing in concentration. In contrast, IE of PKO resulted in the formation of more short and medium chain TAG, with LaLaO and LaMO (La, lauric acid; C, capric acid) experiencing noteworthy increments. Both Rhizomucor miehei and Pseudomonas sp. lipases showed high affinity in hydrolyzing PO fatty acids, resulting in high TAG losses and formation of high percentages of partial glycerides while these lipases were found to enhance the synthesis process in IE of PKO. Catalysis of the three binary blends caused similar TAG compositional changes where the synthesis process focussed on the medium chain TAG, while hydrolysis was observed in the short and long chain TAG that showed corresponding decreases. Catalysis of the three blends was influenced by the major fraction of these blends. Among these blends, PO: PKO at a 1:1 ratio exhibited the highest degree of IE. The diversity and quantity of available TAG are postulated to be the main causes of the different catalytic activities in these binary blends with Pseudomonas sp. lipase showing a higher degree and rate of IE than R. miehei.     

Purification and characterization of an extracellular lipase from Mucor hiemalis f. corticola isolated from soil

We have screened 39 microfungi isolates originated from soil in terms of lipolytic activity. Out of all screened, a novel strain of Mucor hiemalis f. corticola was determined to have the highest lipase activity. The extracellular lipase was produced in response to 2% glucose and 2.1% peptone. The lipase was purified 12.63-folds with a final yield of 27.7% through following purification steps; ammonium sulfate precipitation, dialysis, gel filtration column chromatography and ion exchange chromatography, respectively. MALDI-TOF MS analysis revealed 31% amino-acid identity to a known lipase from Rhizomucor miehei species. The molecular weight of the lipase was determined as 46kDa using SDS-PAGE and analytical gel filtration. Optimal pH and temperature of the lipase were determined as 7.0 and 40°C, respectively. The enzyme activity was observed to be stable at the pH range of 7.0-9.0. Thermostability assays demonstrated that the lipase was stable up to 50°C for 60min. The lipase was more stable in ethanol and methanol than other organic solvents tested. Furthermore, the activity of the lipase was slightly enhanced by SDS and PMSF. In the presence of p-NPP as substrate, K(m) and V(max) values of the lipase were calculated by Hanes-Woolf plot as 1.327mM and 91.11μmol/min, respectively.     

ENZYMATIC SYNTHESIS OF STRUCTURED LIPIDS: TRANSESTERIFICATION OF TRIOLEIN AND CAPRYLIC ACID

Structured lipids were successfully synthesized by lipase-catalyzed trans-esterification (acidolysis) of caprylic acid and triolein in nonaqueous medium. Twelve commercially available lipases (10%, w/w substrates) were screened for their ability to form structured lipid by incubating 100 mg triolein and 65.3 mg caprylic acid in 3 ml hexane at 55C for 24 h. The products were analyzed by reverse-phase high performance liquid chromatography (HPLC) with evaporative light scattering detection. Monocapryloolein was the major component of the products (57.4 mol %) and IM60 lipase from Rhizomucor miehei was the best biocatalyst. Dicapryloolein and triolein contents were 35.4% and 5.3%, respectively. Temperature, mole ratio, time course, incubation media, added water, enzyme load, and substrate concentration were also investigated in this study. The results suggest that it is possible to synthesize structured lipids with lipase as biocatalyst.     

Lipase-catalyzed interesterification in packed bed reactor using 2 different temperatures

Lipase-catalyzed interesterification of high oleic sunflower oil and fully hydrogenated soybean oil (70 : 30, wt/ wt) was carried out in a packed bed reactor using an immobilized lipase from Thermomyces lanuginosus (Lipozyme TL IM) and the effect of a stepwise temperature protocol involving the 2 different temperatures, 60 and 70 °C, was investigated. The melting point of a fat that was incubated at 70 °C for 9 min was 57 °C, which suggested that it should be to employ a lower reaction temperature of 60 °C, after the first 9 min of the reaction. There were no significant differences (P < 0.05) in the conversion degree, triacylglycerol profile, and solid fat content between a constant temperature protocol (70 °C) and a stepwise temperature protocol (a combination of 70 and 60 °C). After 50 cycles, the overall residual activities of enzymes employed in stepwise temperature protocol were significantly (P < 0.05) higher than those of enzymes employed in constant temperature protocol.     

BATCH ENZYMATIC SYNTHESIS, CHARACTERIZATION AND OXIDATIVE STABILITY OF DHA-CONTAINING STRUCTURED LIPIDS

Fortification of processed foods with n-3 polyunsaturated fatty acids (n-3 PUFA) is rarely practiced in North America. This study utilized, DHA single cell oil (DHASCO), an algal source of PUFA (docosahexaenoic acid, DHA), for the synthesis of structured lipids (SL) and compared the oxidative stability and melting characteristics of the products with those of native DHASCO as control. Immobilized lipase, IM60 from Rhizomucor miehei was the biocatalyst. DHASCO was modified with caprylic, oleic, or stearic acids as acyl donors, in a stirred-batch reactor, to produce three different SL. The reactions were performed at 55C for 48 h in n-hexane for caprylic and oleic acid SL, and at 60C for stearic acid-SL. Mole ratio of substrates were 1:6 for DHASCO-C8:0, 1:2 for DHASCO-C18:1, and 1:1 for DHASCO-C18:0. Mol% incorporation and the fatty acids at the sn-2 position of the SL were determined by gas chromatography (GC).
After DHASCO oil modification, mol% of the incorporated fatty acids were 47.6, 46.3 and 31.2 for C8:0, C18:1, and C18:0-containing SL, respectively. Alkaline extraction was a better deacidification method than short-path distillation, and reduced free fatty acid levels to 0.3% in all SL. DHA was the predominant fatty acid at the sn-2 position in all the SL. DHASCO melting peak was -10.6C. The melting peaks for the SL were -10 and -6.2C for oleic-SL, -8.1 and -0.7C for caprylic-SL, and 16.0, 20.4, and 34.4C for stearic-SL. Oxidative stability studies showed that SL were less stable to oxidation than DHASCO, with DHASCO-18:0 being the most susceptible. With the addition of adequate antioxidants, such SL products synthesized from DHASCO will be stabilized and may be useful in DHA fortification of processed foods such as nutrition bars, dressings, infant formula or in functional foods.     

Differential scanning calorimetric studies on structured lipids from coconut oil triglycerides containing stearic acid

Triglycerides from coconut oil contain high levels of lauric acid. They were replaced by incremental amounts of stearic acid by interesterification reactions catalyzed by immobilized lipase (IM 60 from Rhizomucor miehei). The reactions were carried out in organic solvents such as hexane. Maximum incorporation of stearic acid was observed by 4 h at 37vv°C or by 2 h at 60vv°C when triglycerides to fatty acid (stearic acid) ratio was maintained at 1v:Ң. The stearic acid level in coconut oil triglycerides was increased from an initial value of 2% to 60% under these conditions. The stearic acid replaced lauric, myristic, and palmitic acids in unmodified triglycerides. A major portion of stearic acid incorporated was found in positions 1 and 3 of triglycerides. Differential scanning calorimetry indicated that stearic acid enrichment increased the solid fat content and also the higher melting polymorphs in modified lipids. The studies also indicated that low melting polymorphic forms of coconut oil triglycerides are converted to higher melting forms by stearic acid enrichment. The modified lipids thus obtained can find use in various food applications.