Production of specific-structured lipids (SSL) by lipase-catalyzed interesterification has been attracting more and more attention recently. However, it was found that acyl migration occurs during the reaction and causes the production of byproducts. In this paper, the elucidation of acyl migration by response surface design was carried out in the Lipozyme IM (Rhizomucor miehei)-catalyzed interesterification between rapeseed oil and capric acid in solvent-free media. A five-factor response surface design was used to evaluate the influence of five major factors and their relationships. The five factors, water content, reaction temperature, enzyme load, reaction time and substrate ratio, were varied at three levels together with two star points. All parameters besides substrate ratio had strong positive influences on acyl migration, and reaction temperature was most significant. The contour plots clearly show the interactions between the parameters. The migration rates of different fatty acids were also compared from three different sets of experiments during the lipase-catalyzed reaction. The best-fitting quadratic response surface model was determined by regression and backward elimination. The coefficients of determination (R 2 ) of the model were 0.996 and 0.981 for Q 2 value. The results show that the fitted quadratic model satisfactorily expresses acyl migration for the enzymatic interesterification in the batch reactor used.

Studies on formula-fed infants indicate a beneficial effect of dietary DHA on visual acuity. Cross-sectional studies have shown an association between breast-milk DHA levels and visual acuity in breast-fed infants. The objective in this study was to evaluate the biochemical and functional effects of fish oil (FO) supplements in lactating mothers. In this double-blinded randomized trial, Danish mothers with habitual fish intake below the 50th percentile of the Danish National Birth Cohort were randomized to microencapsulated FO [1.3 g/d long-chain n-3 FA (n-3 LCPUFA)] or olive oil (OO). The intervention started within a week after delivery and lasted 4 mon. Mothers with habitual high fish intake and their infants were included as a reference group. Ninety-seven infants completed the trial (44 OO-group, 53 FO-group) and 47 reference infants were followed up. The primary outcome measures were: DHA content of milk samples (0, 2, and 4 mon postnatal) and of infant red blood cell (RBC) membranes (4 mon postnatal), and infant visual acuity (measured by swept visual evoked potential at 2 and 4 mon of age). FO supplementation gave rise to a threefold increase in the DHA content of the 4-mon milk samples (P < 0.001). DHA in infant RBC reflected milk contents (r = 0.564, P < 0.001) and was increased by almost 50% (P < 0.001). Infant visual acuity was not significantly different in the randomized groups but was positively associated at 4 mon with infant RBC-DHA (P = 0.004, multiple regression). We concluded that maternal FO supplementation during lactation did not enhance visual acuity of the infants who completed the intervention. However, the results showed that infants with higher RBC levels of n-3 LCPUFA had a better visual acuity at 4 mon of age, suggesting that n-3 LCPUFA may influence visual maturation.

We compared the absorption of eicosapentaenoic (EPA, 20:5n-3), docosahexaenoic (DHA, 22:6n-3), and decanoic acids in mesenteric lymph duct-cannulated rats following intragastric administration of two oils with different intramolecular triacylglycerol structures. One oil had a specific triacylglycerol structure with EPA and DHA located in the sn-2 position and decanoic acid in the sn-1 and sn-3 positions (specific M-n3-M) whereas the other oil had a random fatty acid distribution (random M-n3-M). The mol% (mol/100 mol total fatty acids) of fatty acids in the two oils was similar, with approximately 66 mol% of decanoic acid and 22 mol% of EPA and DHA. The lymphatic transport (microgram/min) of EPA and DHA as well as the mol% in the total lymph lipids were significantly (both P < 0.01) increased following intragastric administration of specific M-n3-M compared with random M-n3-M. The mol% of decanoic acid in the total lymph lipids was significantly (P < 0.01) higher after random M-n3-M compared with specific M-n3-M but the transport (microgram/min) of decanoic acid was not significantly different. We conclude that under our experimental conditions specific M-n3-M with EPA and DHA predominantly in the sn-2 position of the triacylglycerols was a more readily absorbed source of EPA and DHA and in this context should be investigated further for the potential use in clinical nutrition.

Effects of water content, reaction time, and their relationships in the production of two types of specific-structured lipids (sn-MLM-and sn-LML-types: L-long chain fatty acids; Mmedium chain fatty acids) by lipase-catalyzed interesterification in a solvent-free system were studied. The biocatalyst used was Lipozyme IM (commercial immobilized lipase). The substrates used for sn-MLM-type were fish oil and capric acid, and medium chain triacylglycerols and sunflower free fatty acids for sn-LML-type. The observed incorporation with the time course agrees well with the Michaelis-Menten equation, while the acyl migration is proportional to time within the range of 20 mol% acyl migration (MLM-type: M f = 0.2225T, R 2 = 0.98; LML-type: M f = 0.5618T, R 2 = 0.99). As water content (wt%, on the enzyme basis) increased from 3.0 to 11.6% for MLM-type and from 3.0 to 7.2% for LML-type in the solvent-free systems, the incorporation rates in the first 5 h increased from 3.34 to 10.30%/h, and from 7.29 to 11.12%/h, respectively. However, the acyl migration rates also increased from 0.22 to 1.12%/h and from 0.56 to 1.37%/h, respectively. Different effects in the production of two totally position-opposed lipids can be observed. Presumably these are caused by the different chain length of the fatty acids. The relationships between reaction time and water content are inverse and give a quantitative prediction of incorporation and acyl migration in selected reaction conditions and vice versa. The acyl migration can not be totally avoided in present systems, but can be reduced to a relatively low level. Acyl migration during the downstream processing has also been observed and other factors influencing the acyl migration are briefly discussed. JAOCS 75, 301-308 (1998).Recently there has been increasing interest in the production of specific-structured lipids (SSL) containing medium-chain fatty acids (FA) by lipase-catalyzed interesterification. One of the advantages of this method over chemical ones is that SSL can be produced with particular FA in specific positions to target specific diseases and metabolic conditions, and for optimal nutrition for particular population groups. The perspectives and promises of SSL have been discussed (1,2). Some detailed reviews on the general applications of lipasecatalyzed interesterification have been published recently (3-6).Specific-structured lipids have been reported to have beneficial effects on immune function, nitrogen balance, and improved lipid clearance from the bloodstream (2,7). Free FA liberated from food during absorption are metabolized more easily if they are medium-or short-chain, i.e., C 10 or below. Monoacylglycerols can be absorbed directly. Therefore, essential or desired FA are most efficiently utilized from the sn-2 position in acylglycerols. In accordance with this, triacylglycerols (TG) with short-or medium-chain FA at the sn-1 and sn-3 positions and functional FA at the sn-2 position are rapidly hydrolyzed with pancreatic lipase and absorbed efficiently into mucosal cel...

Interesterification of a blend of palm stearin and coconut oil (75:25, w/w), catalyzed by an immobilized Thermomyces lanuginosa lipase by silica granulation, Lipozyme TL IM, was studied for production of margarine fats in a 1-or 300-kg pilot-scale batch-stirred tank reactor. Parameters and reusability were investigated. The comparison was carried out between enzymatic and chemical interesterified products. Experimentally, Lipozyme TL IM had similar activity to Lipozyme IM for the interesterification of the blend. Within the range of 55-80°C, temperature had little influence on the degree of interesterification for 6-h reaction, but it had slight impact on the content of free fatty acids (FFA). Drying of Lipozyme TL IM from water content 6 to 3% did not affect its activity, whereas it greatly reduced FFA and diacylglycerol contents in the products. Lipozyme TL IM was stable in the 1-kg scale reactor at least for 11 batches and the 300-kg pilot-scale reactor at least for nine batches. Due to regiospecificity of the lipase (sn-1,3 specific), enzymatically interesterified products had different fatty acid distribution at sn-2 position from the chemically randomized products, implying the potential nutritional benefits of the new technology.Paper no. J9703 in JAOCS 78, 57-64 (January 2001).Interest in applications of enzyme technology for the production of plastic fats for food uses is increasing in both academia and industry. Currently the application of enzyme technology is limited since the price of current commercial lipases is too high for industry to produce low-price plastic fats. A new immobilized Thermomyces (Humicola) lanuginosa lipase, named Lipozyme TL IM, was recently developed with the immobilization method of silica granulation (1). Lipozyme TL IM has sn-1,3 specificity and hydrophilic character. It is less expensive than the commonly applied commercial lipase Lipozyme IM (Rhizomucor miehei lipase) and offers an opportunity for industry to reduce the process cost and make the production of low-price plastic fats economically competitive to the conventional chemical randomization.Previously T. lanuginosa lipase was investigated mostly in solvent systems in free-state or immobilized forms (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). From kinetic studies, it was found that immobilized T. lanuginosa lipase had different characteristics depending on the solvent systems and the hydrophobicity of carriers (2,7). Transesterification and alcoholysis reactions catalyzed by the immobilized lipases of R. miehei and T. lanuginosa on Silica Gel 60 showed less regiospecificity in hexane media, whereas they showed strong 1,3-specificity in a more polar system using diethyl ether as the medium (2). The lipolytic activity of immobilized T. lanuginosa lipase depended largely on the substrate used and hydrophobicity of its carrier. A highly hydrophobic carrier enhanced lipase activity for alcoholysis reactions, whereas the reverse effect was observed for acylglycerol synthesis (7). Comparison of hydrolysis and esterificat...