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The lipase-catalyzed interesterification of extra virgin olive oil (EVOO) and fully hydrogenated palm oil (FHPO) was studied in a batch reactor operating at 75°C. The compositions of the semi-solid fat products depend on the reaction conditions and the initial ratio of EVOO to FHPO. The dependence of the quasi-equilibrium product TAG profile on the reaction time was determined for initial weight ratios of EVOO to FHPO from 80:20 to 20:80. Lipozyme TL IM, Lipozyme RM IM and Novozym 435 were employed as biocatalysts. The interesterification reaction was optimized with respect to the type and loading of biocatalyst. Equilibrium was approached in the shortest time with Novozym 435 (80% conversion in 4 h). The chemical, physical, and functional properties of the products were characterized. Appropriate choices of the reaction conditions and the initial ratio of EVOO to FHPO lead to TAG with melting profiles and solid fat contents similar to those of commercial products. Differences were observed in the solid fat contents, melting profiles, and oxidative stabilities of the various interesterified products and also between the indicated properties of each category of product and the corresponding physical blend of the precursor reagents.

An immobilized lipase from Thermomyces lanuginosus (TL IM) was employed to mediate the continuous transesterification of sesame oil and fully hydrogenated soybean oil (FHSBO) in a packed-bed reactor operating at 70 degrees C. Reactions between sesame oil (rich in LLL (15.97%), LOL (31.56%), and OLO (21.15%) [L = linoleic; O = oleic]) and the fully hydrogenated fat ((73.7% SSS, 26.3% SPS) [S = stearic; P = palmitic]) produced semi-solid fats. These products are complex mixtures of triacylglycerol (TAG) species whose compositions depend on reaction conditions. The dependence of the steady state product TAG profile on space time was determined for four initial weight ratios of sesame oil to hydrogenated fat (90:10, 80:20, 70:30, and 60:40). Except for the trial involving a weight ratio of sesame oil to FHSBO of 60:40, near equilibrium conditions were achieved at space times of 30 min-1 h. The chemical, physical, and functional properties of the product semi-solid fats were characterized. The predominant TAG species in the quasi-equilibrium products obtained from the mixture initially containing 90% (w/w) sesame oil and 10% FHSBO were LOL (26.22%) and OLO (21.92%). For transesterification of 80% sesame oil and 20% FHSBO, the major product species were OOP (21.27%), LOL (17.46%), and OLO (13.93%). OOP (24.38%) was the major product for reaction of 70% sesame oil with 30% FHSBO. Appropriate choices of reaction conditions and initial ratios of sesame oil to FHSBO lead to TAG with melting profiles and solid fat contents (SFC) similar to those of a variety of commercial products.

Optimized interesterification of virgin olive oil with a fully hydrogenated fat in a batch reactor: Effect of mass transfer limitationsThe lipase-catalyzed interesterification of virgin olive oil and fully hydrogenated palm oil (FHPO) was studied in a batch reactor operating at 75 7C. The reactions between olive oil {rich in OOO (32.36%), OPO (21.7%) and OLO (11.6%) [L = linoleic; O = oleic; P = palmitic acid]} and the fully hydrogenated fat {(36.5% PSP, 28.8% PPP, 23.2% SPS) [S = stearic acid]} produced semi-solid fats. For an initial weight ratio of olive oil to FHPO of 60 : 40, the reaction product is a complex mixture of triacylglycerol (TAG) species. The TAG profile of the fat product is time dependent. Because of the high viscosity of the liquid reagent phase, it was important to determine if mass transfer effects were significant. Hence, the reaction was optimized with respect to the type and speed of agitation employed, temperature, use of solvent, and the type of biocatalyst. Three immobilized lipases [from Thermomyces lanuginosus (TL IM), Rhizomucor miehei (RM IM) and Candida antarctica B (Novozym 435)] were compared as catalysts for the interesterification reaction. Equilibrium is reached four times faster (in 1-4 h) with a magnetic stirrer to provide agitation than when agitation is not sufficient, i.e. when orbital agitation is employed. Equilibrium was reached faster with Lipozyme TL IM than with the other two lipases. The effects of all the factors investigated on the composition of the products have also been determined. Semi-solid fats obtained with the non-specific Novozym 435 contain levels of unsaturated fatty acid residues on sn-2 sites that are similar to the products obtained with the 1(3)-regiospecific enzymes Lipozyme TL IM and RM IM. The chemical properties of the product semi-solid fat were characterized. The fat prepared using optimal reaction conditions contained 17.20% OPO, 13.61% OOO, 11.09% POP, and 10.35% OSP isomers as the primary products. The induction time obtained in the assay of the oxidative stability of the fat product was 21 h at 98 7C. The lipases Lipozyme TL IM and Novozym 435 were very stable with residual activities of 90 and 100%, respectively, after 15 batch reaction cycles.

Interesterification in batch and continuous flow processes of sesame oil and fully hydrogenated fat catalyzed by immobilized lipaseLipase-mediated interesterification of sesame oil and a fully hydrogenated soybean oil was studied at 70 7C in both a batch reactor (BR) and a continuous-flow packed-bed reactor (PBR) using four different initial weight ratios of substrates (90 : 10, 80 : 20, 70 : 30 and 60 : 40) with Lipozyme TL IM (Thermomyces lanuginosa) as the biocatalyst. Reaction rates were determined by following the dependence of the profile of the product triacylglycerols (TAG) on the reaction time (BR) or the space time (PBR) via RP-HPLC-ELSD. Product TAG identities were confirmed by HPLC-APCI-MS. Primary differences between the performances of the two reactors were the maximum level of net hydrolysis (ca. 3 and 10 wt-% lower acylglycerols at equilibrium for the PBR and BR, respectively), the time or space time required to approach quasi-equilibrium conditions, and less migration of acyl groups in the PBR trials. For the BR trials, quasi-equilibrium conditions were approached in 4-6 h, while for the PBR trials short space times (15 min to 2 h) were sufficient to produce effluent compositions similar to equilibrium BR compositions. The predominant TAG families formed by interesterification were LLS, PSO, PSL, SSL, and SSO (L = linoleic; S = stearic; P = palmitic; O = oleic). Oxidative stabilities, melting profiles and solid fat contents were determined for selected reaction products. Keywords IntroductionEnzyme-mediated interesterification of blends of oils and fats has been extensively studied as an alternative to the combination of partial hydrogenation and chemical interesterification used industrially for the production of specialty and trans-free plastic fats. Several reports dealing with the use of lipase-mediated reactions to improve the physical, nutritional, and chemical properties of naturally occurring fats have been published in the past decade [1]. When these reactions involve only triacylglycerols (TAG) as substrates and when careful control of the water content in the reaction medium is maintained, production of byproducts such as free fatty acids (FFA) and lower acylglycerols can be held at minimal levels. The resulting product distribution constitutes an important economic advantage of the enzyme-catalyzed reaction because the need for further purification procedures is thereby reduced or eliminated [2].Several solid fats (e.g. stearins, completely hydrogenated fats) have been proposed as substrates for use in lipasecatalyzed interesterification processes intended to produce edible plastic fat products. Some of the oils used in previous studies of the exchange of acyl groups with palm stearins include coconut oil, sunflower oil, and palm kernel oil [3][4][5]. Other saturated TAG (e.g. tristearin and tripalmitin) have also been utilized with similar intent by List et al. [6] and Seriburi and Akoh [7]. Exchange of acyl groups from vegetable oils with those from fully hydrogenated soybean oil...