Production of Structured Triacylglycerol via Enzymatic Interesterification of Medium-Chain Triacylglycerol and Soybean Oil Using a Pilot-Scale Solvent-Free Packed Bed Reactor

Oils rich in medium- and long-chain triacylglycerols (MLCT) serve as functional oils to help reduce body fat accumulation and weight gain. However, most of the MLCT-rich products on the market are physical blends of medium- and long-chain triacylglycerols (MCT and LCT, respectively) that are not structured triacylglycerols (TAG). In this study, an efficient pilot-scale packed bed reactor (PBR) of immobilized lipase from Thermomyces lanuginosus (Lipozyme® TL IM, Novozymes, Bagsvaerd, Denmark) was employed for producing structured MLCT via 1,3-specific interesterification of TAG enriched in caprylic and capric acyl groups and soybean oil (SBO). The PBR was operated under continuous recirculation mode in the absence of solvent. Optimal reaction conditions were determined to be: caprylic/capric TAG: SBO ratio (45:55 w/w), reaction temperature (75 °C) and residence time (16.0 min) on MLCT production were studied. When employing a pilot-scale PBR (100 kg day⁻¹) under optimal conditions, a product containing 76.61 wt% MLCT was produced. Lipozyme TL IM was reused for 25 successive batch reactions (125 kg substrates) with no significant reduction in catalytic efficiency. The light yellow MLCT-enriched product had a high level of saturated fatty acids (SFA, 82.74 wt%) in its sn-2 position as a result of the enzyme's 1,3-positional specificity. One-stage molecular distillation and methanol extraction were used to remove the free fatty acids, mono-, and diacylglycerols generated from hydrolysis. With distillation temperature of 150 °C and oil-to-methanol ratio of 1:3 v/v, MLCT content was further increased to 80.07 wt%. The enzymatic PBR was therefore effective in producing structured MLCT at a pilot-scale under solvent-free conditions.     

Enzymatic Interesterification of Extra Virgin Olive Oil with a Fully Hydrogenated Fat: Characterization of the Reaction and Its Products

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.     

Enzymatic fractionation of fatty acids: Enrichment of γ-linolenic acid and docosahexaenoic acid by selective esterification catalyzed by lipases

Immobilized lipase preparations from seedlings of rape (Brassica napus L.) andMucor miehei (lipozyme) used as biocatalysts in esterification and hydrolysis reactions discriminate strongly against γ-linolenic and docosahexaenoic acids/acyl moieties. Utilizing this property, γ-linolenic acid contained in fatty acids of evening primrose oil has been enriched seven to nine-fold, from 9.5 to almost 85% by selective esterification of the other fatty acids with butanol. Similarly, docosahexaenoic acid of cod liver oil has been enriched four to five-fold, from 9.4 to 45% by selective esterification of fatty acids (other than docosahexaenoic acid) with butanol. As long as the reaction is stopped before reaching equilibrium, very little of either γ-linolenic acid or docosahexaenoic acid are converted to butyl esters, which results in high yields of these acids in the unesterified fatty acid fraction.     

In search of a model system for exploring the Chemical Legacy Hypothesis:Drosophila melanogaster and geraniol

We required an experimental system in which to explore elements of the chemical legacy hypothesis, according to which molecules of environmental chemicals may persist on or in the body or immediate surroundings of larval or pupal insects and influence their habitat preferences in adulthood by affecting the maturation of the chemosensory pathways. Using a purpose-built apparatus which exploited the geotactic and phototactic behavior ofDrosophila melanogaster, we examined the pattern of responses to a range of dilutions of geraniol, a terpene of plant origin. Fruit flies avoided the geraniol at high concentrations. Although attraction at low doses and reduced aversion after larval, pupal, or early adult exposure to geraniol have been reported, we did not find either. Thus, we failed to generate the phenomenon described as pre-imaginal conditioning required for the model system. We discuss the results in relation to designing suitable assays for testing the Chemical Legacy Hypothesis.