Synthesis of structured triacylglycerols by lipase-catalyzed acidolysis in a packed bed bioreactor

Structured triacylglycerols (ST) from canola oil were produced by enzymatic acidolysis in a packed bed bioreactor. A commercially immobilized 1,3-specific lipase, Lipozyme IM, from Rhizomucormiehei, was the biocatalyst and caprylic acid the acyl donor. Parameters such as substrate flow rate, substrate molar ratio, reaction temperature, and substrate water content were examined. High-performance liquid chromatography was used to monitor the reaction and product yields. The study showed that all of the parameters had effects on the yields of the expected di-incorporated (dicaprylic) ST products. Flow rates below 1 mL/min led to reaction equilibrium, and lower flow rates did not raise the incorporation of caprylic acid and the product yield. Incorporation of caprylic acid and the targeted di-incorporated ST was increased by approximately 20% with temperature increase from 40 to 70 degrees C. Increasing the substrate molar ratio from 1:1 to 7:1 increased the incorporation of caprylic acid and the product yield slightly. Water content in the substrate also had a mild influence on the reaction. Water content at 0.08% added to the substrate gave the lowest incorporation and product yield. The use of solvent in the medium was also studied, and results demonstrated that it did not increase the reaction rate at 55 degrees C when 33% hexane (v/v) was added. The main fatty acids at the sn-2 position of the ST were C(18:1), 54. 7 mol %; C(18:2), 30.7 mol %; and C(18:3), 11.0 mol %.     

富含EPA/DHA型结构磷脂的酶法合成条件优化及表征

为建立富含二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)型结构磷脂的制备方法,本试验以南极磷虾磷脂为原料,以EPA和DHA总结合率为指标,通过响应面法优化富含EPA/DHA型结构磷脂的酶法合成反应参数,并采用气相色谱(GC)和亲水作用色谱-质谱联用(HILIC-MS)技术对其结构进行表征。结果表明,最优酶催化反应条件为:底物质量比(游离脂肪酸:磷脂, m/m)5.15,反应温度55.22℃,水分添加量(以反应底物总质量计)0.92%,酶添加量(以反应底物总质量计)20%,正己烷3 mL,反应时间24 h,所得结构磷脂中EPA/DHA结合率达64.35%;经GC和HILIC-MS综合分析可知,结构磷脂中磷脂酰胆碱(PC)亚类40:10(20:5/20:5)(18.46%),42:11(20:5/22:6)(12.78%)和38:6(18:1/20:5&16:0/22:6) (7.07%)等分子种含量较高;溶血磷脂酰胆碱LPC亚类20:5(20:5/0:0)(34.40%),22:6(22:6/0:0)(25.99%)和O-16:0(O-16:0/0:0)(10.22%)等分子种含量较高;结构磷脂的PC和LPC组分中脂肪酸单链平均长度≥20的分子种相对含量较原料磷脂分别提高了33.12和37.28个百分点;结构磷脂的PC组分中双键数≥5和双键数≥10的分子种相对含量较原料磷脂分别提高了24.89和27.53个百分点,表明该方法有效提高了结构磷脂中EPA和DHA的含量。本研究结果为进一步探索和丰富酶促合成EPA/DHA型结构磷脂的机理和实践提供了一定的数据支持。     

Synthesis of structured lipids by transesterification of trilinolein catalyzed by Lipozyme IM60

Structured lipids (SL) containing caprylic, stearic, and linoleic acids were synthesized by enzymatic transesterification using Lipozyme IM60. Pure trilinolein and free fatty acids were used as substrates. Incorporation of stearic acid was higher than that of caprylic acid in all parameters. Highest incorporations of both acids were achieved at 32 h, mole ratio of 1:4:4 (trilinolein/caprylic/stearic acids), water content of 1% (wt %), temperature of 55 degrees C, and 10% (wt %) enzyme load. The maximal incorporations of caprylic and stearic acids were 23.73 and 62.46 mol %, respectively. Reaction time, water content, and enzyme load had major influences on the reaction, whereas substrate mole ratio and temperature showed less influence. Lipozyme showed good stability over six reuses. Differential scanning calorimetric analysis of SL gave a melting profile with a very low melting peak of 0-3.3 degrees C and a solid fat content of 25.21% at 0 degrees C. The melting profile and solid fat content of SL were compared with those of fats extracted from commercially available solid and liquid margarine products. The data suggest that enzymatically produced SL could be used in liquid margarine products.     

Synthesis of structured triacylglycerols containing caproic acid by lipase-catalyzed acidolysis: optimization by response surface methodology.

Production in a batch reactor with a solvent-free system of structured triacylglycerols containing short-chain fatty acids by Lipozyme RM IM-catalyzed acidolysis between rapeseed oil and caproic acid was optimized using response surface methodology (RSM). Reaction time (t(r)), substrate ratio (S(r)), enzyme load (E(l), based on substrate), water content (W(c), based on enzyme), and reaction temperature (T(e)), the five most important parameters for the reaction, were chosen for the optimization. The range of each parameter was selected as follows: t(r) = 5-17 h; E(l) = 6-14 wt %; T(e) = 45-65 degrees C; S(r) = 2-6 mol/mol; and W(c) = 2-12 wt %. The biocatalyst was Lipozyme RM IM, in which Rhizomucor miehei lipase is immobilized on a resin. The incorporation of caproic acid into rapeseed oil was the main monitoring response. In addition, the contents of mono-incorporated structured triacylglycerols and di-incorporated structured triacylglycerols were also evaluated. The optimal reaction conditions for the incorporation of caproic acid and the content of di-incorporated structured triacylglycerols were as follows: t(r) = 17 h; S(r) = 5; E(l) = 14 wt %; W(c) = 10 wt %; T(e) = 65 degrees C. At these conditions, products with 55 mol % incorporation of caproic acid and 55 mol % di-incorporated structured triacylglycerols were obtained.     

Antiatherogenic effects of structured lipid containing conjugated linoleic acid in C57BL/6J mice

Conjugated linoleic acids (CLA) were enzymatically acidolyzed with olive oil to produce structured lipids (SL), and their antiatherosclerotic properties were investigated in C57BL/6J mice. Twenty-eight mice were divided into four groups and fed control diet or atherogenic diets supplemented with high cholesterol and high fat (HCHF) containing 5% of lard, olive oil, or SL based on control diet for 4 weeks. The supplementation of SL diet (0.6% CLA) significantly reduced the levels of serum total cholesterol and total triglyceride and increased high-density lipoprotein cholesterol level as compared to lard and olive oil diet groups (p < 0.05). The activity of liver acyl CoA:cholesterol acyltransferase (ACAT) of mice fed the SL diet was significantly lower than that of mice fed the lard or olive oil diet. A reduced formation of aortic fatty streak was observed in SL group. The extent of CLA incorporation depended on tissues or types of phospholipids. More CLA was incorporated in adipose tissue (1.85 mol %) than in the liver (0.33 mol %). Besides, more CLA was found in phosphatidylethanolamine (PE) (0.47 mol %) than in phosphatidylcholine (PC) (0.05 mol %) of hepatic phospholipids. Hepatic phospholipids (PC and PE) of mice fed the SL diet contained reduced contents of arachidonic and linoleic acid compared with mice fed the olive oil or lard diet. The present study suggests that SL could be considered as a functional oil for preventing risks of atheroscelerosis.     

A new insight into the formation of odor active carbonyls by thermally-induced degradation of phospholipids in self-assembly structures

The role of molecular organization in heated aqueous dispersions of egg phosphatidylcholine (PC) and egg phosphatidylethanolamine (PE) was studied with respect to the formation of key odorants. Evidence was found for the crucial role of self-assembly structures adopted by phospholipid molecules on the quantitative composition of volatile constituents. The concentrations of seven aldehydes and one vinyl ketone were determined by isotope dilution assay in heated aqueous dispersions of PC and PE present in various ratios. Addition of PE to PC drastically decreased the amount of (E,E)-2,4-decadienal formed, which cannot be explained by the differences in the fatty acid composition of PC and PE. The free amino group in PE does not explain this phenomenon either, as replacing PE by phosphatidic acid distearylester also reduced the amounts of (E,E)-2,4-decadienal. We suggest that the type of self-assembly structure adopted by phospholipids in water significantly influences the reaction yields. However, the mechanisms leading to the preferred formation of phospholipid-derived odorants in a lamellar phase, as compared to the reversed hexagonal phase, remain unknown.     

Modeling of lipase-catalyzed acidolysis of sesame oil and caprylic Acid by response surface methodology: optimization of reaction conditions by considering both acyl incorporation and migration

Lipase-catalyzed acidolysis in hexane to produce structured lipids (SLs) from sesame oil and caprylic acid was optimized by considering both total incorporation (Y1) and acyl migration (Y2). Response surface methodology was applied to model Y1 and Y2, respectively, with three reaction parameters: temperature (X1), reaction time (X2), and substrate molar ratio (X3). Well-fitting models for Y1 and Y2 were established after regression analysis with backward elimination and verified by a chi2 test. All factors investigated positively affected Y1. For Y2, X1 showed the greatest positive effect. However, there was no effect of X3. We predicted the levels of Y2 and acyl incorporation into sn-1,3 positions (Y3) based on Y1. The results showed that over the range of ca. 55 mol % of Y1, Y3 started to decrease, and Y2 increased rapidly, suggesting that Y1 should be kept below ca. 55 mol % to prevent decrease in quality and yield of targeted SLs.     

Comparative evaluation of the emulsifying properties of phosphatidylcholine after enzymatic acyl modification

The ability of enzymatically synthesized structured phosphatidylcholine (PC) containing caprylic acid to form and stabilize oil-in-water emulsions prepared with different triglycerides [medium chain triglycerides (MCT), soybean oil, and enzymatically synthesized structured lipids] was examined and compared with natural soybean PC and deoiled lecithin. Emulsions were prepared with varying oil and emulsifier concentrations. The particle size distribution, creaming stability, and viscosity were measured for the evaluation of the emulsifying properties. With an increase in the oil concentration, there was an increase in particle size, viscosity, and creaming layer. With an increase in the phospholipid (PL) concentration, there was usually a decrease in particle size and an increase in viscosity, where the emulsion stability was increased. General emulsions prepared with structured lipids resulted in smaller particle sizes as compared to MCT and soybean oil. Deoiled lecithin was able to increase the viscosity more significantly and give smaller particle sizes as compared to the other emulsifiers, thus producing more stable emulsions. However, in certain cases, structured PC was superior to deoiled lecithin and soybean PC. This observation was made for emulsions prepared with soybean oil or structured lipid at an oil/water ratio of 10:90. At an oil/water ratio of 30:70, the deoiled lecithin performed better as compared to the other PLs with all oil types. However, structured PC produced more stable emulsions as compared to natural soybean PC in MCT and soybean oil.     

Lipase-catalyzed acidolysis of tripalmitin with hazelnut oil fatty acids and stearic acid to produce human milk fat substitutes

Structured lipids (SLs) containing palmitic, oleic, stearic, and linoleic acids, resembling human milk fat (HMF), were synthesized by enzymatic acidolysis reactions between tripalmitin, hazelnut oil fatty acids, and stearic acid. Commercially immobilized sn-1,3-specific lipase, Lipozyme RM IM, obtained from Rhizomucor miehei was used as the biocatalyst for the enzymatic acidolysis reactions. The effects of substrate molar ratio, reaction temperature, and reaction time on the incorporation of stearic and oleic acids were investigated. The acidolysis reactions were performed by incubating 1:1.5:0.5, 1:3:0.75, 1:6:1, 1:9:1.25, and 1:12:1.5 substrate molar ratios of tripalmitin/hazelnut oil fatty acids/stearic acid in 3 mL of n-hexane at 55, 60, and 65 degrees C using 10% (total weight of substrates) of Lipozyme RM IM for 3, 6, 12, and 24 h. The fatty acid composition of reaction products was analyzed by gas-liquid chromatography (GLC). The fatty acids at the sn-2 position were identified after pancreatic lipase hydrolysis and GLC analysis. The results showed that the highest C18:1 incorporation (47.1%) and highest C18:1/C16:0 ratio were obtained at 65 degrees C and 24 h of incubation with the highest substrate molar ratio of 1:12:1.5. The highest incorporation of stearic acid was achieved at a 1:3:0.75 substrate molar ratio at 60 degrees C and 24 h. For both oleic and stearic acids, the incorporation level increased with reaction time. The SLs produced in this study have potential use in infant formulas.     

Stereospecific analysis of triacylglycerol and phospholipid fractions of five wild freshwater fish from Poyang Lake

The fatty acids (FA) compositions and positional distributions in triacylglycerols (TAG) and phospholipids (PL) of five wild freshwater fish (Squaliobarbus curriculus, Erythroculter ilishaeformis, Pseudobagrus fulvidraco, Bostrichthys sinensis, and Siniperca kneri Garman) from Poyang Lake (the largest freshwater lake of China) were studied. For TAG, S. kneri German had the highest content (13.59%) of n - 3 polyunsaturated fatty acids (PUFA) and E. ilishaeformis had the lowest ratio of (n - 6)/(n - 3) (0.65). PL had a high content of PUFA, which declined in the order of phosphatidylethanolamine (PE) > phosphatidylcholine (PC) > TAG. 9c11t-18:2 accounted for 6.38-50.77% of total conjugated linoleic acids (CLA). The highest level of odd-branched chain fatty acids (OBCFA) was 26.7% in B. sinensis. The study revealed that the distribution of FA among the sn positions was not random: monounsaturated fatty acids (MUFA) and PUFA preferred positions 1 and 3 and saturated fatty acids (SFA) position 2 of TAG, while SFA and MUFA predominated over sn-1-PL and PUFA over sn-2-PL.     

Chemical and physical properties of butterfat-vegetable oil blend spread prepared with enzymatically transesterified canola oil and caprylic acid

Structured Lipid was synthesized from canola oil and caprylic acid with sn-1,3 specific lipase from Rhizomucor miehei. Cold spreadable butter was made by blending butterfat with the SL at a weight ratio of 80:20. Its chemical and physical properties were compared with pure butter and butterfat-canola oil 80:20 blend spread. The butterfat-SL blend had lower contents of hypercholesterolemic fatty acids (FAs) and the lowest atherogenic index (AI) as compared to the others. Melting and crystallization behaviors of butterfat-SL blend were similar to those of butterfat-canola oil blend above 0 degrees C. It showed solid fat contents (SFCs) similar to butterfat-canola oil blend but lower than pure butterfat. The butterfat-SL blend was shown to crystallize in the beta' form. There were no differences between the hardness of butterfat-SL blend spread and butterfat-canola oil blend spread. Rheological analysis showed that butterfat-SL blend spread lost its elastic behavior at 5 degrees C, a lower temperature than pure butter.     

Lipid characterization of mangrove thraustochytrid--Schizochytrium mangrovei

Lipid class composition and distribution of fatty acids within the lipid pool of microalga, Schizochytrium mangrovei FB3 harvested at the late exponential phase, was studied, with special emphasis on the distribution of docosahexaenoic acid (C22:6 n-3, DHA). Neutral lipids were the major lipid constituents (95.90% of total lipids) in which triacylglyerol (TAG) was the predominant component and accounted for 97.20% of the neutral lipids. Phosphatidylcholine (PC) was the major polar lipid. Phosphatic acid and phosphatidylserine were the two classes in phospholipids reported for the first time in thraustochytrids. Both TAG and PC were primarily saturated and consisted of C16:0 at approximately 50% of total fatty acids. DHA was found to be distributed in all lipid classes and to be the major polyunsaturated fatty acid. TAG contained the highest amount of DHA, although the percentage of DHA in total fatty acids in TAG (29.74%) was lower than that in PC (39.61%). The result from this study would be useful for further optimization of DHA production by S. mangrovei.     

Odorants generated by thermally induced degradation of phospholipids

The qualitative and quantitative aroma composition of heated aqueous dispersions of egg phosphatidylcholine (PC) and egg phosphatidylethanolamine (PE) were characterized by aroma extract dilution analysis and isotope dilution assay. On the basis of FD-factors and odor activity values, trans-4,5-epoxy-(E)-2-decenal was found to be the most potent odorant followed by (E,E)-2,4-decadienal, 1-octen-3-one, and hexanal. The amount of (E,E)-2,4-decadienal in PC was about 20-fold higher compared to PE, while hexanal was the major odor-active compound in the PE sample. (E,Z,Z)-2,4,7-Tridecatrienal was identified for the first time as an odor-active volatile constituent of heated phospholipids exhibiting a characteristic egg white-like note. Further odorants first reported in thermally treated phospholipids were (Z)-2-decenal, (E)-2-decenal, and (E)-2-undecenal. Differences in the fatty acid composition of PC and PE can only partially explain the quantitative results found in this study, thus suggesting that further parameters may influence the formation of carbonyls from heated aqueous dispersions of phospholipids.     

Acidolysis of tristearin with selected long-chain fatty acids

Five lipases, namely, Candida antarctica (Novozyme-435), Mucor miehei (Lipozyme-IM), Pseudomonas sp. (PS-30), Aspergillus niger (AP-12), and Candida rugosa (AY-30), were screened for their effect on catalyzing the acidolysis of tristearin with selected long-chain fatty acids. Among the lipases tested C. antarctica lipase catalyzed the highest incorporation of oleic acid (OA, 58.2%), gamma-linolenic acid (GLA, 55.9%), eicosapentaenoic acid (EPA, 81.6%), and docosahexaenoic acid (DHA, 47.7%) into tristearin. In comparison with other lipases examined, C. rugosa lipase catalyzed the highest incorporation of linoleic acid (LA, 75.8%), alpha-linolenic acid (ALA, 74.8%), and conjugated linoleic acid (CLA, 53.5%) into tristearin. Thus, these two lipases might be considered promising biocatalysts for acidolysis of tristearin with selected long-chain fatty acids. EPA was better incorporated into tristearin than DHA using the fifth enzymes. LA incorporation was better than CLA. ALA was more reactive than GLA during acidolysis, except for the reaction catalyzed by Pseudomonas sp., possibly due to structural differences (location and geometry of double bonds) between the two fatty acids. In another set of experiments, a combination of equimolar quantities of unsaturated C18 fatty acids (OA + LA + CLA + GLA + ALA) was used for acidolysis of tristearin to C18 fatty acids at ratios of 1:1, 1:2, and 1:3. All lipases tested catalyzed incorporation of OA and LA into tristearin except for M. miehei, which incorportaed only OA. C. rugosa lipase better catalyzed incorporation of OA and LA into tristearin than other lipases tested, whereas the lowest incorporation was obtained using Pseudomonas sp. As the mole ratio of substrates increased from 1 to 3, incorporation of OA and LA increased except for the reaction catalyzed by A. niger and C. rugosa. All lipases tested failed to allow GLA or CLA to participate in the acidolysis reaction, and ALA was only slightly incoporated into tristearin when M. miehei was used.     

Lipase-catalyzed incorporation of different Fatty acids into tripalmitin-enriched triacylglycerols: effect of reaction parameters

Tripalmitin-enriched triacylglycerols were concentrated from palm stearin by acetone fractionation and as the substrate reacted with a mixture of equimolar quantities of fatty acids (C8:0-C18:3). The incorporation degree and acyl migration level of the fatty acids and acylglycerols composition were investigated, providing helpful information for the production of human milk fat substitutes. Higher incorporation degrees of the fatty acids were obtained with lipase PS IM, Lipozyme TL IM, and Lipozyme RM IM followed by porcine pancreatic lipase and Novozym 435-catalyzed acidolysis. During reactions catalyzed by Lipozyme TL IM, Lipozyme RM IM, and lipase PS IM, incorporation degrees of C12:0, C14:0, C18:1, and C18:2 were higher than those of other fatty acids at operated variables (molar ratio, temperature, and time), and the triacylglycerols content reached the highest (82.09%) via Lipozyme RM IM-catalyzed acidolysis. On the basis of significantly different levels of acyl migration to the sn-2 position, lipases were in the order of lipase PS IM < Lipozyme TL IM < Lipozyme RM IM.     

鸡油组织中的磷脂对鸡油挥发性风味化合物形成的影响

磷脂是肉类特征性风味的重要前体物质。鸡油具有浓郁的脂香和鸡汤香气,磷脂可能对其风味有重要作用。本文采用去除鸡油组织中的磷脂,以及在鸡油中添加磷脂等处理方法,结合顶空固相微萃取-气相色谱-质谱联用技术和感官评价方法研究经不同处理鸡油中的挥发性风味物质相对含量和风味的变化。结果表明添加了磷脂的鸡油,其特征性风味成分显著增加,特别是（E,E）-2,4-癸二烯醛和1-辛烯-3-酮分别增加了4.5倍和10.4倍;而去除磷脂鸡油的挥发性风味物质种类和丰度显著减少;感官评价结果也表明添加磷脂鸡油的风味最浓郁,而去除磷脂鸡油的风味最弱。因此,该研究证明鸡油组织中的磷脂对鸡油的风味具有重要的贡献作用,添加磷脂可显著增加鸡油的香气。该研究结果为浓香鸡油的开发提供理论依据和参考工艺。     

Analysis of polar lipids in the serum from rats fed shiitake by liquid chromatography-mass spectrometry/mass spectrometry

Consumption of a shiitake mushroom diet has been reported to have effects on serum phospholipids. However, much less is known about the effect on serum polar lipids including lysophospholipids and free fatty acids. In the present study, the effects of a shiitake diet were evaluated on the basis of identification and quantification of individual polar lipid components in rat serum using liquid chromatography-mass spectrometry/mass spectrometry. By comparison with standards and published data, 50 lysophospholipids and 32 free fatty acids were identified, and the concentrations of 27 polar lipids in rat serum were determined. Shiitake diets decreased the levels of all individual polar lipid components in the serum of male rat. The total level of serum polar lipids in males fed 4% shiitake diets (1365.71 mol/L) was significantly lower than that of the control (2270.26 mol/L). However, shiitake diets did not significantly affect the levels of serum polar lipids in female rats.     

Lipid [corrected] classes, fatty acids, and sterols in seafood from Gilbert Bay, southern labrador

Seafood from Gilbert Bay, southern Labrador, was sampled for lipid classes, fatty acid, and sterol composition. Gilbert Bay is a proposed Marine Protected Area, and the composition of seafood from this region is interesting from both human health and ecological perspectives. Analyses included four species of bivalves and flesh and liver samples from four fish species. Lipids from a locally isolated population of northern cod (Gadus morhua) were also compared to lipids from other cod populations. Lipid classes were analyzed by Chromarod/Iatroscan TLC-FID, fatty acids by GC, and sterols by GC-MS. Three cod populations had similar levels of total lipid per wet weight (0.6%) with triacylglycerols (TAG), sterols, and phospholipids comprising on average 13, 11, and 51%, respectively, of their total lipids. Fatty fish such as capelin and herring contained on average 8.4% lipid with 86% present as TAG. Fish livers from cod and herring showed opposite trends, with cod having elevated lipid (27%) and TAG (63%) and herring containing only 3.8% lipid and 20% TAG. Shellfish averaged 0.6% lipid; however, significant lipid class differences existed among species. Fatty acid analysis showed few significant differences in cod populations with on average 57% polyunsaturated fatty acids (PUFA), 18% monounsaturated fatty acids (MUFA), and 24% saturated fatty acids (SFA). Cod livers had lower PUFA (34%) and elevated MUFA (44%) relative to flesh. Bivalves averaged 25% SFA, 18% MUFA, and 57% PUFA, whereas scallop adductor muscle had the highest PUFA levels (63%). Bivalves contained 20 different sterols with cholesterol present as the major sterol (19-39%). trans-22-Dehydrocholesterol, brassicasterol, 24-methylenecholesterol, and campesterol individually accounted for >10% in at least one species. High levels of PUFA and non-cholesterol sterols observed in Gilbert Bay seafood demonstrate their positive attributes for human nutrition.     

Lipase-catalyzed modification of rice bran oil to incorporate capric acid

Capric acid (C10:0) was incorporated into rice bran oil with an immobilized lipase from Rhizomucor miehei as the biocatalyst. Effects of incubation time, substrate mole ratio, enzyme load, and water addition on mole percent incorporation of C10:0 were studied. Transesterification was performed in an organic solvent, hexane, and under solvent-free condition. Pancreatic lipase-catalyzed sn-2 positional analysis and tocopherol analysis were performed before and after enzymatic modification. Products were analyzed by gas-liquid chromatography (GLC) for fatty acid composition. After 24 h of incubation in hexane, there was an average of 26.5 +/- 1.8 mol % incorporation of C10:0 into rice bran oil. The solvent-free reaction produced an average of 24.5 +/- 3.7 mol % capric acid. In general, as the enzyme load, substrate mole ratio, and incubation time increased, the mole percent of capric acid incorporation also increased. Time course reaction indicated C10:0 incorporation increased up to 27.0 mol % at 72 h, for the reaction in hexane, and up to 29.6 mol % at 12 h, for the solvent-free reaction. The highest C10:0 incorporations (53.1 and 43.2 mol %) for the mole ratio experiment occurred at a mole ratio of 1:8 for solvent and solvent-free reactions, respectively. The highest C10:0 incorporation (27.9 mol %) for the reaction in hexane occurred at 10% enzyme load, and the highest incorporation (34.4 mol %) for the solvent-free reaction occurred at 20% enzyme load. Incorporation of C10:0 into rice bran oil declined with the addition of increasing amounts of water after reaching 30.3 mol % at 2% water addition in hexane, and in the solvent-free reaction after reaching 35.9 mol %.     

Synthesis and characterization of canola oil-stearic acid-based trans-free structured lipids for possible margarine application

Incorporation of stearic acid into canola oil to produce trans-free structured lipid (SL) as a healthy alternative to partially hydrogenated fats for margarine formulation was investigated. Response surface methodology was used to study the effects of lipozyme RM IM from Rhizomucor miehei and Candida rugosa lipase isoform 1 (LIP1) and two acyl donors, stearic acid and ethyl stearate, on the incorporation. Lipozyme RM IM and ethyl stearate gave the best result. Gram quantities of SLs were synthesized using lipozyme RM IM, and the products were compared to SL made by chemical catalysis and fat from commercial margarines. After short-path distillation, the products were characterized by GC and RPHPLC-MS to obtain fatty acid and triacylglycerol profiles, 13C NMR spectrometry for regiospecific analysis, X-ray diffraction for crystal forms, and DSC for melting profile. Stearic acid was incorporated into canola oil, mainly at the sn-1,3 positions, for the lipase reaction, and no new trans fatty acids formed. Most SL products did not have adequate solid fat content or beta' crystal forms for tub margarine, although these may be suitable for light margarine formulation.