Changes in olive oil composition due to microwave heating

The effects of microwave heating on some components of extra-virgin olive oil were studied. Traditional parameters, including free acidity, peroxide value and ultraviolet absorbance values at 232 and 268 nm, were determined in six extra-virgin olive oil samples before and after the microwave treatment. Significant differences (P<0.01) were detected for free acidity, peroxide, and ultraviolet absorbance at 268 nm; also, the absorbances at 232 nm showed significant differences (P<0.05) between treated and untreated samples. The glycerolic fractions, triacylglycerols (TAG), diacylglycerols (DAG), and monoacylglycerols (MAG), were isolated by thin-layer chromatography. The respective percentage fatty acid (FA) composition and percentage amount were obtained by high-resolution gas chromatography with an internal standard. For the most abundant TAG fraction, the stereospecific analysis was carried out to obtain the FA percentage compositions of the three sn-positions. Small but significant modifications were observed regarding the decrease in the TAG percentage and increases in the DAG and MAG percentage amounts. No significant changes were observed for the FA compositions of TAG, DAG, and MAG fractions before and after the treatment. Nevertheless, the results of TAG stereospecific analysis showed losses of unsaturated FA in all sn-positions. Higher percentage changes in the sn-1- than in sn-2-position of TAG were observed. Regarding the volatile fraction, different profiles were obtained after the treatment.     

Analysis of diastereomeric DAG naphthylethylurethanes by normal-phase HPLC with on-line electrospray MS

Normal-phase HPLC resolution of sn-1,2(2,3)- and x-1,3-DAG generated by partial Grignard degradation from natural TAG was carried out with both (R)-(−) and (S)-(+)-1-(1-naphthyl)ethylurethane derivatives. The diastereomeric sn-1,2- and sn-2,3-DAG derivatives were resolved using two Supelcosil LC-Si (5 μm, 25 cm × 4.6 mm i.d.) columns in series and an isocratic elution with 0.37% isopropanol in hexane at a flow rate of 0.7 mL/min. The DAG were detected by UV absorption at 280 nm and were identified by electrospray ionization MS in the positive ion mode following postcolumn addition of chloroform/methanol/30% ammonium hydroxide (75∶24.5∶0.5, by vol) at 0.6 mL/min. Application of the method to a stereospecific analysis of the molecular species of TAG of rat VLDL showed that the TAG composition of VLDL circulating under basal conditions differs markedly from that of VLDL secreted by the liver during inhibition of serum lipases. The inhibition of serum lipases resulted in a significant proportional decrease in 16∶0 and PUFA and an increase in 18∶0 and oligoenoic FA in the sn-1-position, whereas the FA compositions in the sn-2- and sn-3-positions were much less affected.     

Lipase-catalyzed acidolysis of menhaden oil with pinolenic acid

Lipase-catalyzed acidolysis of menhaden oil with a pinolenic acid (PLA) concentrate, prepared from pine nut oil, was studied in a solvent-free system. The PLA concentrate was prepared by urea complexation of the FA obtained by saponification of pine nut oil. Eight commercial lipases from different sources were screened for their ability to catalyze the acidolysis reaction. Two different types of structured lipids (SL) were synthesized. The first type, which has PLA residues as a primary FA residue at the sn-1,3 positions of the TAG, was synthesized using a 1,3-regiospecific lipase, namely, Lipozyme RM IM from Rhizomucor miehei. The second type of SL, which has PLA residues as a primary FA residue at both the sn-1,3 and sn-2 positions of the TAG, was synthesized using a nonspecific lipase, namely, Novozym 435 from Candida antarctica. The effects of variations in enzyme loading, temperature, and reaction time on PLA incorporation into the oil were monitored by GC analyses. The optimal temperature and enzyme loading for synthesis of the two types of SL were 50°C and 10% of the total weight of substrates for both enzymes. The optimal reaction time for the synthesis with Lipozyme RM IM was 16h, whereas the optimal reaction time for the synthesis mediated by Novozym 435 was 36 h. Pancreatic lipase-catalyzed sn-2 positional analyses were also carried out on the TAG samples.     

Lipase-catalyzed synthesis of structured triacylglycerides from 1,3-diacylglycerides

A new method for the lipase-catalyzed synthesis of structured TAG (ST) is described. First, sn1,3-dilaurin or-dicaprylin were enzymatically synthesized using different published methods. Next, these were esterified at the sn2-position with oleic acid or its vinyl ester using different lipases. Key to successful enzymatic synthesis of ST was the choice of a lipase with appropriate FA specificity, i.e., one that does not act on the FA already present in the sn1,3-DAG, but that at the same time exhibits high selectivity and activity toward the FA to be introduced. Reactions were performed in the presence of organic solvents or in solvent-free systems under reduced pressure. With this strategy, mixed ST containing the desired compounds 1,3-dicaprylol-2-oleyl-glycerol or 1,3-dilauroyl-2-oleyl-glycerol (CyOCy or LaOLa) were obtained at 87 and 78 mol% yield, respectively, using immobilized lipases from Burkholderia cepacia (Amano PS-D) in n-hexane at 60°C. However, regiospecific analysis with porcine pancreatic lipase indicated that in CyOCy, 25.7% caprylic acid and in LaOLa 11.1% lauric acid were located at the sn2-position. Oleic acid vinyl ester was a better acyl donor than oleic acid. Esterification of sn1,3-DAG and free oleic acid gave very low yield (<20%) of ST in a solvent system and moderate yield (>50%) in a solvent-free system under reduced pressure.     

Preparation of regioisomers of structured TAG consisting of one mole of CLA and two moles of caprylic acid

TAG (MLM) with medium-chain FA (MCFA) at the 1,3-positions and long-chain FA (LCFA) at the 2-position, and TAG (LMM) with LCFA at the 1(3)-position and MCFA at 2,3(1)-positions are a pair of TAG regioisomers. Large-scale preparation of the two TAG regioisomers was attempted. A commercially available FFA mixture (FFA-CLA) containing 9-cis, 11-trans (9c, 11t)- and 10t,12c-CLA was selected as LCFA, and caprylic acid (C₈FA) was selected as MCFA. The MLM isomer was synthesized by acidolysis of acyglycerols (AG) containing two CLA isomers with C₈FA: A mixture of AG-CLA/C₈ FA (1∶10, mol/mol) and 4 wt% immobilized Rhizomucor miehei lipase was agitated at 30°C for 72 h. The ratio of MLM to total AG was 51.1 wt%. Meanwhile, LMM isomer was synthesized by acidolysis of tricaprylin with FFA-CLA: A mixture of tricaprylin/FFA-CLA (1∶2, mol/mol) and 4 wt% immobilized R. miehei lipase was agitated at 30°C for 24 h. The ratio of LMM to total AG was 51.8 wt%. MLM and LMM were purified from 1,968 and 813 g reaction mixtures by stepwise short-path distillation, respectively. Consequently, MLM was purified to 92.3% with 49.1% recovery, and LMM was purified to 93.2% with 52.3% recovery. Regiospecific analyses of MLM and LMM indicated that the 2-positions of MLM and LMM were 95.1 mol% LCFA and 98.3 mol% C₈ FA, respectively. The results showed that a process comprising lipase reaction and short-path distillation is effective for large-scale preparation of high-purity regiospecific TAG isomers.     

Lipase-assisted acidolysis of high-laurate canola oil with eicosapentaenoic acid

The production of structured lipids via acidolysis of high-laurate canola oil (Laurical 15) with EPA in hexane was carried out using lipase from Pseudomonas sp. The optimal reaction conditions used 4% lipase, at a mole ratio of oil to EPA of 1∶3 at 45°C over 36 h. The positional distribution of FA on the glycerol backbone of unmodified oil indicated that lauric acid was mainly located at the sn-1,3 positions. Stereospecific analysis of the oil modified with EPA showed that lauric acid remained mostly esterified to the sn-1,3 positions of the TAG molecules and that EPA was also primarily in the sn-1,3 positions of the TAG molecules. Thus, the resultant structured lipids may have optimal value for use in applications where quick energy release and EPA supplementation are required.     

Production of Human Milk Fat Substitutes by Interesterification of Tripalmitin with Ethyl Oleate Catalyzed by Candida parapsilosis Lipase/Acyltransferase

In human milk fat, the saturated fatty acids, namely palmitic acid, are located at the sn-2 position of triacylglycerols (TAG) while unsaturated fatty acids (e.g. oleic acid) are esterified at position sn-1,3. Thus, sn-1,3-dioleoyl-2-palmitoylglycerol (OPO) is the target TAG to be used as human milk fat substitutes (HMFS) in infant formulas. In this study, the noncommercial recombinant lipase/acyltransferase from Candida parapsilosis (CpLIP2) was immobilized in Accurel MP1000, and used as a biocatalyst for the interesterification of tripalmitin with ethyl oleate in a solvent-free medium, to obtain structured lipids used as HMFS. Different molar ratios (MR) of ethyl oleate to tripalmitin (2:1–8:1) were used. After 4 h reaction at 60°C, about 30 mol% of oleic acid incorporation was already observed for all tested MR. An apparent equilibrium was reached after 8–24 h, with 32–51 mol% final incorporation, increasing with the MR. The incorporation of oleic acid into TAG was compared with the maximum predicted values when a random or a sn-1,3-regioselective biocatalyst was used. The obtained values are consistent with the maximum incorporation expected for a sn-1,3-regioselective enzyme. In fact, the amount of oleic acid at position sn-2 was approximately 15% for all the MR tested, which is explained by the acyl migration phenomenon. CpLIP2 exhibited higher activity than most commercial immobilized lipases (e.g. faster reaction in solvent-free media, low enzyme load, and low MR needed), and showed a recognized sn-1,3 regioselective behavior.     

The regiospecific position of 18∶1 cis and trans monoenoic fatty acids in milk fat triacylglycerols

TAG of butterfat were fractionated according to the type and degree of unsaturation into six fractions by silver-ion HPLC. The fractions containing TAG with either cis-or trans-monoenoic FA were collected and fractionated further by reversed-phase HPLC to obtain fractions containing cis TAG of ACN:DB (acyl carbon number:double bonds) 48∶1, 50∶1, and 52∶1 as well as trans 48∶1, 50∶1, and 52∶1. The FA compositions of these fractions were elucidated by GC. The MW distribution of each fraction was determined by ammonia negative-ion CI-MS. Each of the [M-H]⁻ parent ions was fractionated further by collision-induced dissociation with argon, which gave information on the location of cis-and trans-FA between the primary and secondary positions of TAG. The results suggest that the sn-positions of the monoenoic cis-and trans-FA depend on the two other FA present in the molecule. With 14∶0 FA in the TAG molecule, the 18∶1 FA in the sn-2 position are mostly present as cis-isomers. When there is no 14∶0 in the TAG molecule, the trans-18∶1 isomers seem to be more common in the sn-2 position. Also when other long-chain FA are present, the trans-isomers are more likely to be located in the secondary (sn-2) position.     

Distribution of medium-chain FA in different lipid classes after administration of specific structured TAG in rats

Structured TAG (STAG) containing medium-chain FA (MCFA) in the sn-1,3 positions and essential FA in the sn-2 position were synthesized by lipase-catalyzed acidolysis. In our previous studies we found that part of the MCFA from STAG could be absorbed in the small intestine; however, it was unclear how they were absorbed. In order to get a better understanding of the metabolism of STAG to improve future design and application of STAG, in the present study lymph lipids collected after feeding STAG were fractionated into different classes and the FA composition of each lipid class was studied by GC after methylation to FAME. Caprylic acid was detected in the fraction of TAG only after administration of 1,3-dioctanoyl-2-linoleyl-sn-glycerol (8∶0/18∶2/8∶0), whereas lauric acid was detected in TAG, DAG, and FFA as well as phospholipids after administration of 1,3-didodecanoyl-2-linoleyl-sn-glycerol (12∶0/18∶2/12∶0). We conclude that the enterocyte has the ability to reacylate the MCFA into TAG and that the intestinal absorption of MCFA from STAG mainly occurs by resynthesis of TAG. Caprylic acid from STAG is not incorporated into phospholipids, whereas lauric acid from STAG can be incorporated into phospholipids.     

Synthesis of 1,3-dicapryloyl-2-docosahexaenoylglycerol by a combination of nonselective and <Emphasis Type="Italic">sn</Emphasis>-1,3-selective lipase reactions

A two-step consecutive synthetic method for the production of symmetrical, structured lipids by a combination of nonselective and sn-1,3 regioselective ester exchange reactions was investigated. In the first step, TAG with unspecifically substituted DHA were obtained by reacting tricapryloylglycerol (CCC) with ethyl docosahexanoate (EtDHA) using the lipase QLM (from Alcaligenes sp.), followed by removing the ethyl ester and CCC by molecular distillation. In the second step, sn-1,3 regioselective ester exchange was achieved by reacting the resulting TAG with ethyl caprylate (EtC) using the immobilized lipase Novozyme 435 (Candida antarctica lipase), followed by distillation of the ethyl ester and CCC to give sn-1,3-dicapryloyl-sn-2-docosahexaenoylglycerol (CDC). The acylglycerol composition of CDC was analyzed by GLC, which showed that the content of dicapryloyl-docosahexaenoylglycerols (2CD) in the product was 76.4%, and that the ratio of CDC to sn-1,2-dicapryloyl-sn-3-docosahexaenoylglycerol contained in 2CD was 82.7∶17.3 (%). The distillates CCC, EtDHA, and EtC could be recycled repeatedly to produce CDC as the substrate for the consecutive ester exchange reaction. In addition, separation of CCC and EtDHA was unnecessary for reuse. The present method is considered to meet the requirements for industrial utilization, in which simplicity in scaleup, high yields, compact reaction system, and minimal formation of by-products are important factors.     

Regiospecific analysis by ethanolysis of oil with immobilized <Emphasis Type="Italic">Candida antarctica</Emphasis> lipase

A mixture of oil/ethanol (1∶3, w/w) was shaken at 30°C with 4% immobilized Candida antarctica lipase by weight of the reaction mixture. The reaction regiospecifically converted FA at the 1- and 3-positions to FA ethyl esters, and the lipase acted on C₁₄−C₂₄ FA to a similar degree. The content of 2-MAG reached a maximum after 4 h; the content was 28–29 mol% based on the total amount of FA in the reaction mixture at 59–69% ethanolysis. Only 2-MAG were present in the reaction mixture during the first 4 h, and 1(3)-MAG were detected after 7 h. After removal of ethanol from the 4-h reaction mixture by evaporation, 2-MAG were fractionated by silica gel column chromatography. The contents of FA in the 2-MAG obtained by ethanolysis of several oils coincided well with FA compositions at the 2-position, which was analyzed by Grignard degradation. It was shown that ethanolysis of oil with C. antarctica lipase can be applied to analysis of FA composition at the 2-position in TAG.     

Positional distribution of FA in TAG of enzymatically modified borage and evening primrose oils

Stereospecific analysis was carried out to establish positional distribution of FA in the TAG of DHA, EPA, and (EPA+DHA)-enriched oils. In this study, TAG of enzymatically modified oils were purified using a silicic acid column. The TAG were then subjected to positional distribution analysis using a modified procedure involving reductive cleavage with Grignard reagent. The results showed that in DHA-enriched borage oil (BO), DHA was randomly distributed over the three positions of TAG, whereas γ-linolenic acid (GLA) was mainly esterified at the sn-2 and-3 positions. In DHA-enriched evening primrose oil (EPO), however, DHA and GLA were concentrated in the sn-2 position. In EPA-enriched BO, EPA was randomly distributed over the three positions of TAG, similar to that observed for DHA. In EPA-enriched EPO, however, this FA was mainly located at the primary positions (sn-1 and sn-3) of TAG. In both oils, GLA was preferentially esterified at the sn-2 position. In (EPA+DHA)-enriched BO, EPA and DHA were mainly esterified at the sn-1 and -3 positions of TAG, whereas GLA was mainly located at the sn-2 position. In (EPA+DHA)-enriched EPO, GLA was mainly located at the sn-2 and-3 positions; EPA was preferentially esterified at the sn-1 and-3 positions, and DHA was found mainly at the sn-3 position.     

Stereospecific analysis of TAG from sunflower seed oil

Stereospecific analysis of TAG from a sunflower seed oil of Tunisian origin was performed. The TAG were first fractionated according to chain length and degree of unsaturation by RP-HPLC. The four major diacid- and triacid-TAG fractions were palmitoyldilinoleoyl-glycerol, dioleoyllinoleoylglycerol, oleoyldilinoleoylglycerol, and palmitoyloleoyl-linoleoyl-glycerol, amounting to 7.2, 16.6, 29.5, and 12 mol%, respectively. The TAG of the four fractions were individually submitted to stereospecific analysis, using a Grignard-based partial deacylation, separation of sn-1,2(2,3)-DAG from sn-1,3-DAG by boric acid-impregnated silica gel TLC plates, conversion of the sn-1,2(2,3)-DAG to their 3,5-dinitrophenylurethane (DNPU) derivatives, fractionation of DNPU derivatives by RP-HPLC, resolution of the DNPU-DAG by HPLC on a chiral column, transmethylation of each sn-DNPU-DAG fraction, and analysis of the resulting FAME by GC. The data obtained were used to determine the triacyl-sn-glycerol composition of the main TAG of the oil. Fifteen triacyl-sn-glycerols were identified and quantified, representing, along with the monoacid-TAG, trilinoleoylglycerol and trioleoylglycerol, more than 90% of the total oil TAG. The two major triacyl-sn-glycerols were trilinoleoyl-glycerol and 1-linoleoyl-2-linoleoyl-3-oleoyl-glycerol (18.6 and 18.5% of the total, respectively). Results clearly identified linoleic acid as the major FA at the sn-2 position, whereas oleic and palmitic acids were the major FA at the sn-3 position. The sn-1 position was occupied to nearly the same extent by linoleic and oleic acids, and to a greater extent by palmitic acid, which was practically absent at the sn-2 position.     

Synthesis of the structured lipid 1,3-dioleoyl-2-palmitoylglycerol from palm oil

Human milk fat contains 20–25% palmitic acid (16∶0) and 30–35% oleic acid (18∶1). More than 60% of the plamitic acid occurs at the sn-2 position of the glycerol backbone. Palm oil is a rich source of both palmitic and oleic acids. The structured lipid 1,3-dioleyl-2-palmitoylglycerol (OPO) is an important ingredient in infant formula. OPO was synthesized from palm oil by a three-step method. In the first step, low-temperature fractionation was applied to palm oil FA, yielding a palmitic acid-rich fraction (87.8%) and an oleic acid-rich fraction (96%). The palmitic acid content was further increased to 98.3% by transforming palmitic acid into ethyl palmitate. In the second step, esterification of ethyl palmitate and glycerol catalyzed by lipase Novozym 435 under vacuum (40 mm Hg) was employed for the synthesis of tripalmitin. Finally, OPO was obtained by the reaction of tripalmitin. Finally, OPO was obtained by the reaction of tripalmitin with oleic acid catalyzed by Lipase IM 60. In this final step, the TAG content in the product acylglycerol mixture was 97%, and 66.1% oleic acid was incorporated into TAG. Analysis of the FA composition at the sn-2 position of TAG showed 90.7 mol% of palmitic acid and 9.3 mol% of oleic acid. OPO content in the product TAG was ca. 74 mol%. Thus, an efficient method was developed for the synthesis of OPO from palm oil.     

Two-step enzymatic reaction for the synthesis of pure structured triacylglycerides

Structured triacylglycerides with medium-chain fatty acids (caprylic acid) in sn1- and sn3-positions and a long-chain unsaturated fatty acid (oleic or linoleic acid) in the sn2-position of glycerol (MLM) were synthesized by lipase catalysis in a two-step process. First, pure 2-monoacylglycerides (2-MG) were synthesized by alcoholysis of triacylglycerides (triolein, trilinolein, or peanut oil) in organic solvents with 1,3-regiospecific lipases (from Rhizomucor miehei, Rhizopus delemar, and Rhizopus javanicus). The 2-MG were purified by crystallization and obtained in up to 71.8% yield. These 2-MG were esterified in a second reaction with caprylic acid in n-hexane to form almost pure MLM. For 2-MG obtained from peanut oil, the final product contained more than 90% caprylic acid in the sn1- and sn3-positions, whereas the sn2-position was composed of 98.5% unsaturated long-chain fatty acids. Reaction conditions for both steps were optimized with respect to source and immobilization of lipase, water activity, and solvent.     

<Superscript>13</Superscript>C-NMR Regioisomeric Analysis of EPA and DHA in Fish Oil Derived Triacylglycerol Concentrates

The regio-isomeric distribution of the omega-3 polyunsaturated fatty acids (PUFA) cis-5,8,11,14,17-eicosapentaenoic acid (EPA) and cis-4,7,10,13,16,19-docosahexaenoic acid (DHA) in the triacylglycerols (TAG) of anchovy/sardine fish oil was determined by ¹³C nuclear magnetic resonance (NMR) analysis under quantitative conditions. From the measurements of sn-1,3 and sn-2 carbonyl peak areas it was established that EPA was mainly located in the sn-1,3 positions, whereas DHA primarily occupied the sn-2 position. Reconstituted TAG prepared by Candida antarctica lipase-B (CALB) glycerolysis of the ethyl ester (EE) or the free fatty acid (FFA) forms of anchovy/sardine fish oil, displayed a different pattern: EPA was equally distributed, while DHA was preferentially attached to the sn-1,3 positions. TAG concentrates of varying EPA and DHA molar fractions were prepared by CALB-catalyzed glycerolysis of the corresponding EE and FFA. ¹³C-NMR analysis of the purified products revealed a lack of CALB regioselectivity for EPA and a slight sn-1,3 regioselectivity for DHA. Since this pattern was observed in all cases of this study, it was concluded that the lipase regioselectivity during TAG synthesis is independent of both the acyl donor type (carboxylic acid or ester) and the fatty acid content of the oil substrate.     

Triacylglycerol composition of oil from <Emphasis Type="Italic">Pistacia atlantica</Emphasis> fruit growing in Algeria

The distribution of FA between the sn-2 and sn-1,3 positions of TAG from Pistacia atlantica fruit oil of Algeria has been determined. Unsaturated FA showed a preference for the internal position. Linoleic and oleic acids occurred predominantly in the sn-2 position with lesser amounts evenly distributed between the sn-1 and sn-3 positions, as generally found in vegetable oils. The oil was found to contain TAG that were trisaturated (0.93%), disaturated (15.06%), monosaturated (44.64%), and triunsaturated (38.10%). The distribution of the TAG calculated using the lipase hydrolysis technique is slightly different from that determined with HPLC. This is particularly true for trioleoyl and trilinoleoylglycerols. In contrast, the agreement between theory and experiment is good for TAG containing two palmitoyl and one oleoyl, one oleoyl and two linoleoyl, and one palmitoyl and two oleoyl chains.     

Enzymatic Synthesis of Structured Triacylglycerols Containing CLA Isomers Starting from <Emphasis Type="Italic">sn</Emphasis>-1,3-Diacylglycerols

The synthesis of structured triacylglycerols (TAG) by the enzymatic reaction between sn-1,3-diacylglycerols (sn-1,3-DAG) and conjugated linoleic acid (CLA) isomers was studied. Both the substrates of the reaction were produced from vegetable oils, the sn-1,3-DAG from extra virgin olive oil and the CLA isomers from sunflower oil. The enzymatic reactions between these substrates were catalyzed for 96 h by an immobilized lipase from Rhizomucor miehei (Lipozyme IM) and the reactions carried out in solvent were monitored every 24 h by using high-performance liquid chromatography-evaporative light scattering detector (HPLC-ELSD). The enzymatic reactions were carried out in different reaction media (hexane, isooctane and solvent free) and with different CLA/sn-1,3-DAG ratios. Total % acidic composition and structural analysis data were evaluated to verify the presence of CLA isomers in sn-2- position of synthesized TAG. The results showed good levels of CLA incorporation in sn-1,3-DAG, from 19.2% of TAG synthesized in solvent free conditions with a 0.5:1 substrate ratio, to 47.5% of TAG synthesized in isooctane with a 2:1 substrate ratio. It was observed that for all the reaction media, the best sn-2- acylic specificity was obtained with a 0.5:1 substrate ratio.     

Triacylglycerols of Apiaceae seed oils: Composition and regiodistribution of fatty acids

Oils from the seeds of caraway (Carum carvi), carrot (Daucus carota), celery (Apium graveolens) and parsley (Petroselinum crispum), all from the Apiaceae family, were analyzed by gas chromatography for their triacylglycerol (TAG) composition and fatty acid (FA) distribution between the sn‐1(3) and sn‐2 positions of TAG. Twenty‐two TAG species were quantified. Glyceryl tripetroselinate was the major TAG species in seed oils of carrot, celery and parsley, with levels ranging from 38.7 to 55.3%. In caraway seed oil, dipetroselinoyllinoleoylglycerol was the major TAG species at 21.2%, while the glyceryl tripetroselinate content was 11.4%. Other TAG species were linoleoyloleoylpetroselinoylglycerol and dipetroselinoyloleoylglycerol. Predominantly, TAG were triunsaturated (72.2–84.0%) with diunsaturates at 14.4–25.9%, and small amounts of monounsaturated TAG. Results for regiospecific analysis showed a non‐random FA distribution in Apiaceae for palmitic, petroselinic, linoleic and oleic acids. Petroselinic acid was predominantly located at the sn‐1(3) position in carrot, celery and parsley seed oils, while it was mainly at the sn‐2 position in caraway seed oil. The distribution of linoleic acid was opposite to that of petroselinic acid. Oleic acid was mostly located at the sn‐2 position, except for caraway, where it was evenly distributed between the sn‐1(3) and sn‐2 positions. Both the saturated FA, palmitic and stearic acid, were located mainly at the sn‐1(3) position. The presence of a high level of tripetroselinin in parsley seed oil (55.3%) makes it a potential source for the production of petroselinic acid.     

Use of <Emphasis Type="Italic">Rhizopus delemar</Emphasis> lipase as compared with other lipases for determination of <Emphasis Type="Italic">sn</Emphasis>-2 fatty acids in triacylglycerol

The FA composition in the sn-2 position of TAG is routinely determined after porcine pancreatic lipase hydrolysis. However, the content of saturated FA increased when a pancreatic lipase preparation with higher specific activity was used. Lipase from Rhizopus delemar was selected as a potential replacement lipase for the following reasons: (i) The FA specificity is nearly equivalent in hydrolysis activity toward FA such as lauric, myristic, palmitic, palmitoleic, stearic, oleic, linoleic, and α-linolenic acids; and (ii) lipase from R. delemar hydrolyzes fatty acyl residues at the sn-1,3 positions of TAG. Acyl migration products were present at less than 0.8% in lipase hydrolysates containing 6–14% of sn-2 MAG. A reproducibility CV of less than 5% was obtained in a collaborative study in which the compositions of the main FA at the sn-2 position in olive oil were determined using lipase from R. delemar. This article was presented in part at the Biocatalysis Symposium, 94th AOCS Annual Meeting & Expo, Kansas City, Missouri, May 2003.