Preparation and Characterization of Virgin Olive Oil‐Beeswax Oleogel Emulsion Products

Virgin olive oil and beeswax were used to prepare four oleogel emulsions (EM1–EM4) through simultaneous oleogelation emulsification, and these oleogels were compared with breakfast margarine (BM). The melting temperatures of the oleogel emulsions ranged from 52.29 to 57.52 °C, while it was 40.36 °C for the BM sample. Similarly, the solid fat content (SFC) of the oleogel emulsions was between 3.57 and 3.68 % at 20 °C, and that of BM was 7.70 %. Except the EM3 sample, all oleogel emulsions exhibited mechanical stability. The firmness and stickiness values of the oleogel emulsion samples were lower than those of the BM sample, but they remained almost constant through 90 days of storage. Furthermore, the fine water droplets and needle‐like beeswax crystals within the continuous oil phase were stable during the storage. The X‐ray diffraction patterns of the samples revealed that the oleogel emulsions contain crystals similar to β′ polymorphs, characterized by a homogenous, smooth and fine texture. The presence of inter and intramolecular hydrogen bonds was proved by Fourier Transform Infrared (FT‐IR) measurements. The developed oleogel emulsions were found to be stable in terms of texture, color and oxidation during 90 days of storage. In conclusion, these oleogel emulsion products can be used as margarine/spread stocks.     

Effect of oil unsaturation and wax composition on stability,properties and food applicability of oleogels

Oleogelation is emerging as one of the most exigent oil structuring technique. The main objective of this study was to formulate and characterize rice bran/sunflower wax-based oleogels using eight refined food grade oils such as sunflower oil, mustard oil, soybean oil, sesame oil, groundnut oil, rice bran oil, palm oil, and coconut oil. Stability and properties of these oleogels with respect to oil unsaturation and wax composition were explored. Sunflower wax exhibited excellent gelation ability even at 1%–1.5% (w/v) concentration compared to rice bran wax (8%–10% w/v). As the oleogelator concentration increased, peak melting temperature also increased with increase in strength of oleogels as per rheological studies. X-ray diffraction and morphological studies revealed that oleogel microstructure has major influence of wax composition only. Sunflower wax oleogels unveiled rapid crystal formation with maximum oil binding capacity of 99.46% in highly unsaturated sunflower oil with maximum polyunsaturated fatty acid content. Further, the applicability of this wax based oleogels as solid fat substitute in marketed butter products was also scrutinized. The lowest value of solid fat content (SFC) in oleogel was 0.20% at 25°C, resembling closely with the marketed butter products. With increase in oil unsaturation, oleogels displayed remarkable reduction in SFC. Depending upon prerequisite, oleogel properties can be modulated by tuning wax type and oil unsaturation. In conclusion, this wax-based oleogel can be used as solid fat substitute in food products with extensive applications in other fields too.     

Structuring of Chicken Fat by Monoacylglycerols

In this study, we investigated the effect of monoacylglycerol (MAG) as a structuring agent on the physicochemical, microstructure and rheological properties of chicken fat. The fatty acid composition, oxidative stability, free fatty acids (FFA), slip melting point (SMP), solid fat content (SFC), kinetics of crystallization, microstructure and rheological properties of the samples were evaluated. The addition of MAG at a 0.5 % level did not affect the fatty acid composition, induction period of oxidation at 110 °C (IP_ox110), SFC curve or rheological properties of chicken fat (p > 0.05). However, structured samples containing 3.0 and 5.0 % MAG had higher saturated fatty acid (SFA) content, SFC, SMP, FFA content and IP_ox110 (p < 0.05). The addition of MAG led to a reduction in the IP of oxidation at 60 °C (IP_ox60) and increased the oxidation rate of fats, as measured by the Schaal oven test. Samples containing 3–5 % MAG had higher SFC content, higher loss, storage and complex moduli, higher complex viscosity, and a lower induction period of crystallization (IP_cryst) and tan δ than chicken fat. Investigations by polarized light microscopy confirmed the presence of increased crystal content in samples containing higher MAG levels. These results show that structured chicken fats have the potential for application in the production of soft tub margarine and Iranian vanaspati.     

Physicochemical Properties of Foam‐Templated Oleogel Based on Gelatin and Xanthan Gum

In this paper, gelatin and xanthan are applied to produce a foam‐templated oleogel. For this reason, the oleogel is prepared at different concentrations of biopolymers and the properties of solution, cryogel, and related oleogel are determined. The results show that xanthan addition increases viscosity and foam stability of solution. Also, an increment in biopolymer concentration increases cryogel network density (ND) and firmness but has no significant effect on moisture sorption. The oil binding capacity of all oleogels is >92%. In terms of high foam stability (96.87 ± 4.42), low ND (0.016 ± 0.00), and consequently suitable oil sorption (46.10 ± 4.40), the oleogel containing 3% gelatin and 0.2% xanthan is selected as the best sample. Complementary tests exhibit that the oleogel, with thixotropic behavior and 60% structural recovery, can bind the oil at temperature <100 °C. The oleogel network can protect the edible oil from oxidative reaction during 2 month storage. Nonetheless, more studies are needed to attest the application of this oleogel type in food products. Practical Application: Biopolymers of gelatin and xanthan are GRAS and available so that they are applied in many food products. This research shows that the cryogel of these biopolymers, as a hydrophilic oleogelator, can be utilized to structure oil and produce oleogel in an indirect method. This procedure that forms strong gel and keeps oil even at high temperatures can be of interest to scientists who are searching for solid fat substitutes in food products such as cakes, biscuits, and muffins.     

Physical properties of palm‐based diacylglycerol and palm‐based oils in the preparation of shelf‐stable margarine

Ternary mixtures containing palm olein (POL), palm kernel oil (PKO) and palm oil‐based diacylglycerol (PO‐DAG) were designed using mixture design. The corresponding physical properties such as solid fat content (SFC) as well as deviation from SFC (ΔSFC) using nuclear magnetic resonance (NMR) and melting and crystallization properties using differential scanning calorimetry (DSC) were studied. Ternary phase behaviour was analysed using isosolid diagrams. The most intensive eutectic interaction among the three binary blends studied was observed along the binary line of PKO/PO‐DAG followed by POL/PKO and POL/PO‐DAG. The higher ΔSFC did not always lead to the more intensive eutectic behaviour among the blends. Addition of pure POL, 33.33 and 66.66% POL, and no POL to 50/50 mixture of PKO/PO‐DAG decreased heat of crystallization (ΔHc) as well as crystallization onset (T_O). However, as the same amounts of PO‐DAG and PKO were added to the 50/50 mixtures of POL/PKO and POL/PO‐DAG, respectively, blend containing the equi‐mixture of POL, PKO and PO‐DAG (33.33/33.33/33.33) was found to have the lowest ΔHc. This was also reflected in the corresponding eutectic effect observed at 20–25 and 5–10°C, respectively. Palm‐based DAG‐enriched shelf‐stable margarine consisting of POL/PKO/PO‐DAG (42.5/42.5/15 w/w) was optimally formulated through analysis of multiple isosolid diagrams and was found to have quite similar SFC profile with commercial shelf‐stable margarine. Practical applications: In this study, valuable information about complicated interactions among the palm oil‐based diacylglycerol (PO‐DAG) and palm‐based oils with different FA chain length was obtained in the ternary system. These informative data may be useful in future exploitation of solid fat‐based DAG in blend with natural fats for various DAG‐enriched plastic fat products. Furthermore, Design Expert software was found to be a valuable tool to optimize the new fat blend formulation using the minimum number of blend preparation. By using this tool, assessment of complicated behaviour among the blend components through construction of the corresponding phase diagrams which are critical for optimization purposes as well as fat product development, would also be possible.     

Influence of Aqueous Matrices into Candelilla Wax Organogels Emulsions for Topical Applications

Emulgels and bigels are, respectively, partial and total gelified forms of emulsions that can increase stability and bring different permeation and diffusion properties for traditional oil and water mixtures. This work investigated the stability, rheological behavior, and microstructure of bigels and emulgels through a topical application perspective. Candelilla wax (CW)/sunflower oil (5/95) organogels or pure sunflower oil was used to obtain dilute (5% oily phase) and concentrated (40% oily phase) emulsions. It was used three different aqueous phases with each oily phase and oil load: water, sodium polyacrylate hydrogel, and modified starch hydrogel. Dilute emulsions showed better stability with sodium polyacrylate hydrogel forming oil-in-water bigels and emulgels while concentrated emulsions were stable only in water-in-oil emulgels. Thixotropy, network strength, and thermal stability were modulated by the oily phase and concentration used. Concentrated emulgels showed higher spreadability, but strong temperature-dependency. Diluted emulgels and bigels showed high hydrogel influence on stability and rheological properties observed. The results showed the potential of CW organogels to stabilize and modify sensory attributes in bigels and emulgels for topical applications.     

Production of heat-sensitive monoacylglycerols by enzymatic glycerolysis in tert-pentanol: Process optimization by response surface methodology

The aim of this study was to optimize production of MAG by lipase-catalyzed glycerolysis in a tert-pentanol system. Twenty-nine batch reactions consisting of glycerol, sunflower oil, tert-pentanol, and commercially available lipase (Novozym^®435) were carried out, with four process parameters being varied: Enzyme load, reaction time, substrate ratio of glycerol to oil, and solvent amount. Response surface methodology was applied to optimize the reaction system based on the experimental data achieved. MAG, DAG, and TAG contents, measured after a selected reaction time, were used as model responses. Well-fitting quadratic models were obtained for MAG, DAG, and TAG contents as a function of the process parameters with determination coefficients (R²) of 0.89, 0.88, and 0.92, respectively. Of the main effects examined, only enzyme load and reaction time significantly influenced MAG, DAG, and TAG contents. Both enzyme amount and reaction time showed a surprisingly nonlinear relationship between factors (process parameters) and responses, indicating a local maximum. The substrate ratio of glycerol to oil did not significantly affect the MAG and TAG contents; however, it had a significant influence on DAG content. Contour plots were used to evaluate the optimal conditions for the complex interactions between the reaction parameters and responses. The optimal conditions established for MAG yield were: enzyme load, 18% (w/w of oil); glycerol/oil ratio, 7∶1 (mol/mol); solvent amount, 500% (vol/wt of oil); and reaction time, 115 min. Under these conditions, a MAG content of 76% (w/w of lipid phase) was predicted. Verification experiments under optimized reaction conditions were conducted, and the results agreed well with the range of predictions.     

Selective Synthesis of Diacylglycerols of Conjugated Linoleic Acid

Quasi-quantitative selective production of diacylglycerols (DAG) rich in polyunsaturated fatty acids (PUFA) was demonstrated using a Penicillium camembertii lipase. Under optimal initial conditions [60 °C, 10% (w/w) biocatalyst based on total reactants, 5:1 molar ratio of free conjugated linoleic acid (CLA) to hydroxyl groups in partial glycerides consisting of ca. 90% (w/w) monoacylglycerols (MAG) and ca. 10% (w/w) diacylglycerols (DAG)], reaction for only 4.5 h gave 98.62% DAG and 1.38% MAG. The DAG contained >95% unsaturated fatty acid residues. Predominant DAG were LnLn, LnL and LL, although LO and LP were also significant (Ln = linolenic; L = linoleic; O = oleic; P = palmitic). Effects of the acylating agent (free CLA), solvent, and temperature on undesirable side reactions were determined. Reaction selectivities were similar in n-hexane and solvent-free media. The re-esterified products contained less than 7% saturated fatty acids and a higher ratio of unsaturated to saturated fatty acid residues (19.00) than the precursor soybean oil (5.22). The biocatalyst retained 55% of its initial activity after use in three consecutive reaction/extraction cycles.     

Characterization of fish oil-in-water emulsions using light-scattering,nuclear magnetic resonance,and gas chromatography-headspace analyses

The effect of the molecular environment on the physical and oxidative properties of homogenized or microfluidized fish oil-in-water emulsions (5% w/w tuna oil in pH 7 phosphate buffer) stabilized by whey protein isolate (WPI, 1 or 5% w/w) or lecithin (2.5% w/w) was examined. Laser light-scattering measurements showed that WPI-stabilized emulsions had smaller particle sizes than lecithin-stabilized emulsions, and that higher pressures reduced the particle size. WPI afforded more protection against oil oxidation than did lecithin, as evidenced by the lower headspace propanal of emulsions as measured by GC-headspace analysis, despite the larger interface in WPI-stabilized emulsions. Reducing the concentration of WPI in emulsions from 5 to 1% decreased the oxidative stability of WPI-stabilized emulsions. The ¹H NMR transverse relaxation times (T ₂) of FA chains in emulsion droplets stabilized by the same surfactants made by homogenization or microfluidization were different and not always related to particle size. The higher mobility (i.e., longer T ₂) of the unsaturated parts of the FA chains within an oil droplet, compared with the saturated parts, suggests that the unsaturated components tended to stay in the core of the oil droplets. This experimental result supports the hypothesis reported in other literature that the more unsaturated FA are buried in the oil core of oil-in-water emulsions. The lack of a universal correlation between particle size and oxidation suggests that the mobility of particles in an emulsion has an influence on the rate of oxidation.     

Improvement of mono and diacylglycerol production via enzymatic glycerolysis in tert‐butanol system

In this work we report experimental data regarding the glycerolysis of olive oil using Novozym 435 in tert‐butanol organic system aiming at the production of monoacylglycerols (MAG) and diacylglycerols (DAG). Experiments were performed in batch mode, recording the reaction kinetics and evaluating the effects of temperature, enzyme concentration, tert‐butanol:oil/glycerol volume ratio and using solvent to substrates ratio of 1:1 and 5:1 v/v. Experimental results showed that lipase‐catalyzed glycerolysis in tert‐butanol might be a potential route for the production of high contents of MAG and DAG. The results also showed that it is possible to maximize the production of MAG and/or DAG, depending on the glycerol to oil molar ratio employed in the reactional system. Higher contents of MAG (53 wt%) and DAG (50 wt%) were achieved using glycerol to oil molar ratio of 3:1/6:1 and 0.5:1.5, respectively, both in 8 h of reaction at 70°C, 600 rpm and enzyme concentration of 10 wt%.     

Crude Wax Extracted from Rice Bran Oil Improves Oleogel Properties and Oxidative Stability

Crude wax extracted from rice bran oil (RBO) is used to improve the oleogel properties and oxidative stability of RBO. The effect of crude rice bran wax (CrBW) on the formation characteristics and oxidative stability of oleogels is discussed. The results show that oleogels can be formed with 7.0 wt% CrBW at 20 °C. As the concentration of CrBW increases from 7.0 to 11.0 wt%, the hardness and solid fat content (SFC) of the oleogels increase significantly, and the oleogels are primarily β' crystals. Moreover, oleogel crystals formed with 5 and 7 wt% CrBW are flocculent; when the amount included is 9%, the oleogel crystals are transformed into long dendrites, and the density rises. After 90 days of storage at 20 °C, the peroxide value of oleogels formed with 9.0 wt% CrBW slowly rises from 3.21 to 6.52 mmol kg⁻¹. Practical Applications: Oleogels prepared here by CrBW and RBO are an innovative structural lipid without trans fats. Useful information on the rich fats and nutrients in CrBW is provided, which reduces the production cost and improves the industrial production capacity.     

Na2SiO3-Catalyzed Glycerolysis of Sacha Inchi (Plukenetia volubilis L.) Oil into Di- and Monoacylglycerols

Direct glycerolysis of novel edible Sacha Inchi (Plukenetia volubilis L.) seed oil (PvLO) into diacylglycerols (DAG) and monoacylglycerols (MAG) was studied over solid Na₂SiO₃ with or without microwave assistance. The glycerolysis yield was calculated by qualitative and semiquantitative analyses of ¹H NMR, ¹³C NMR, and FT-IR spectra. The yields of ~33% 1, 3-DAG, ~16% 1, 2-DAG, ~40% 1-MAG, and ~2.3% 2-MAG were achieved after 16 hours at 120 °C in three consecutive cycles using acetone, with an interesterification rate of 92%. The modified oil showed enhanced gelation ability at low temperatures. The yield of 1, 2-DAG can be increased by adding acetone as solvent. The fatty acid compositions and unsaturated structure of lipids were less destroyed after alkaline glycerolysis. However, more α-linolenic and linoleic acids were transferred to the sn-2 position of glyceryl skeleton. The oxidative stability of the modified oil was still controllable. In summary, this work provides a feasible method to convert polyunsaturated plant oils into oils rich in DAG and MAG with less destructive impact on the olefinic structure of oil. Also, it provides a useful example of how to quickly evaluate the influence of chemical modification on the chemical structure of plant oils by using various spectral technologies.     

Low‐Temperature Chemical Synthesis of High‐Purity Diacylglycerols (DAG) from Monoacylglycerols (MAG)

A chemical method was developed for low‐temperature synthesis of DAG from MAG followed by an easy purification procedure in order to obtain high‐purity DAG. Solvent‐assisted and solvent‐free reaction conditions were used, combined with different catalysts (sodium methoxide, p‐toluenesulfonic acid, methanesulfonic acid, and sulfuric acid). All reactions were performed at 35 and 70 °C. By increasing both acidity and polarity of the catalyst the equilibrium shifts towards the formation of DAG. When using sulfuric acid in solvent‐assisted condition at 70 °C, 88 % conversion was obtained after 20 min of reaction (77 % w/w DAG in the reaction mixture after evaporation of the solvent). After purifying by means of column chromatography, 96 % pure DAG were obtained. The overall yield of DAG was 81 %.     

Preparation of Docosahexaenoic Acid-Rich Diacylglycerol-Rich Oil by Lipase-Catalyzed Glycerolysis of Microbial Oil from Schizochytrium sp. in a Solvent-Free System

Docosahexaenoic acid (DHA)-rich diacylglycerol (DAG)-rich oil was prepared by lipase-catalyzed glycerolysis of microbial oil from Schizochytrium sp. in a solvent-free system. The reaction parameters including lipase type, substrate molar ratio, temperature, lipase concentration, and reaction time were screened. The selected conditions were determined as follows: Novozym® 435 (Novozymes A/S, Bagsvaerd, Denmark) as biocatalyst at 8 wt%, substrate ratio (DHA-rich microbial TAG/glycerol) of 1:1 mol/mol, temperature of 50 °C, and reaction time of 12 hours. Under these conditions, the triacylglycerol (TAG), DAG, and monoacylglycerol (MAG) contents in the product were 36.4%, 48.2%, and 15.4%, respectively. The lipase was reused successively for 18 cycles without significant loss of activity under the conditions given above. Fatty acid composition analysis of the final product showed that the contents of DHA in TAG, DAG, and MAG were 53.9%, 44.9%, and 34.8%, respectively. DHA-rich DAG has the potential to be used as an ingredient in infant formula to increase the bioavailability of DHA.     

Effects of droplet size on the oxidative stability of oil-in-water emulsions

The effects of droplet size and emulsifiers on oxidative stability of polyunsaturated TAG in oil-in-water (o/w) emulsions with droplet sizes of 0.806±0.0690, 3.28±0.0660, or 10.7±0.106 μm (mean ± SD) were investigated. Hydroperoxide contents in the emulsion with a mean droplet size of 0.831 μm were significantly lower than those in the emulsion with a mean droplet size of 12.8 μm for up to 120 h of oxidation time. Residual oxygen contents in the headspace air of the vials containing an o/w emulsion with a mean droplet size of 0.831 μm were lower compared with those of the emulsion with a mean droplet size of 12.8 μm. Hexanal developed from soybean oil TAG o/w emulsions with smaller droplet size showed significantly lower residual oxygen contents than those of the larger droplet size emulsions. Consequently, oxidative stability of TAG in o/w emulsions could be controlled by the size of oil droplet even though the origins of TAG were different. Spin-spin relaxation time of protons of acyl residues on TAG in o/w emulsions measured by ¹H NMR suggested that motional frequency of some acyl residues was shorter in o/w emulsions with a smaller droplet size. The effect of the wedge associated with hydrophobic acyl residues of emulsifiers was proposed as a possible mechanism to explain differences in oxidative stability between o/w emulsions with different droplet sizes.     

Rat Small Intestinal Mucosal Epithelial Cells Absorb Dietary 1,3‐Diacylglycerol Via Phosphatidic Acid Pathways

Compared with triacylglycerol (TAG), dietary 1,3‐diacylglycerol (1,3‐DAG) is associated with reduced serum lipid and glucose levels. We investigated the metabolism of 1,3‐DAG by assaying its intermediate metabolites during digestion and absorption in the rat small intestine. After gavage with TAG emulsion, TAG was digested mainly to 2‐monoacylglycerol (2‐MAG) and unesterified fatty acid (FFA) in the rat small intestinal lumen. 2‐MAG was directly absorbed into the small intestinal epithelial cells and esterified to 1,2(2,3)‐DAG, and further esterified to TAG. After gavage with 1,3‐DAG emulsion, 1,3‐DAG was digested mainly to 1(3)‐MAG and FFA in the rat small intestinal lumen with subsequent significant increase of 1‐MAG and 1,3‐DAG concentrations in small intestinal mucosal epithelial cells, and the 2‐MAG, 1,2(2,3)‐DAG, and TAG concentrations in mucosal epithelial cells were not significantly different after 1,3‐DAG than after TAG gavage, suggesting that the metabolic pathway of 1,3‐DAG is different from that of TAG. In intestinal mucosal epithelial cells, we further assayed enzyme levels and gene expression of proteins in the phosphatidic acid (PtdOH) pathway. The glycerol kinase, phosphatidate phosphatase, and diacylglycerol acyltransferase‐2 expression and the relative expression of mRNA of enzymes were significantly increased in the 1,3‐DAG group compared with the TAG group, suggesting that TAG synthesis from dietary 1,3‐DAG was mainly via PtdOH pathways, which may partially account for the effect of dietary DAG on postprandial serum TAG.     

Synthesis of MAG of CLA with Penicillium camembertii lipase

CLA has various physiological activities, and a FFA mixture containing almost equal amounts of cis-9,trans-11 and trans-10,cis-12 CLA (named FFA-CLA) has been commercialized. We attempted to produce MAG of CLA by a two-step successive reaction. The first step was esterification of FFA-CLA with glycerol. A mixture of FFA-CLA/glycerol (1∶5, mol/mol), 2 wt% water, and 200 units/g of Penicillium camembertii mono-and diacylglycerol lipase was agitated at 30°C to form a homogeneous emulsion. The esterification degree reached 84% after 10 h. To further increase the degree, the reaction was continued with dehydration at 5 mm Hg. The esterification degree reached 95% after 24 h (34 h in total), and the reaction mixture contained 50 wt% MAG and 44 wt% DAG. The second step was glycerolysis of the resulting DAG. The reaction mixture in the first-step esterification was transferred from the reactor to a beaker and was solidified by vigorous agitation on ice. When the solidified mixture was allowed to stand at 5°C for 15 d, glycerolysis of DAG proceeded successfully, and MAG content in the reaction mixture increased to 88.6 wt%. Hydrolysis of the acylglycerols was not observed during the second reaction. FA composition in the synthesized MAG was completely the same as that in the original FFA-CLA, showing that Penicillium lipase does not have selectivity toward FA in the FFA-CLA preparation.     

Functional Characteristics of Oleogel Prepared from Sunflower Oil with β-Sitosterol and Stearic Acid

β‐Sitosterol (Sit) and stearic acid (SA) were combined at varying ratios (w/w) and added to sunflower oil (SFO) at the concentration of 20 g/100 g oil for preparing edible fat‐like oleogel. The oleogel was characterized using an optical microscope, Fourier transform infrared spectroscopy (FTIR), X‐ray diffractometer (XRD), differential scanning calorimeter, and texture analyzer. The oil‐binding capacity, melting temperature, and firmness of the oleogel increased with the increase in the amount of SA in the gelator combination (Sit:SA, w/w). The microscopic analysis showed that the gel network formed based on the crystallization and self‐organization of gelator molecules, and both gelators showed an independent crystalline behavior in the oleogel. In addition, the FTIR spectra showed that the gel network formed via physical entanglements and was stabilized by non‐covalent interactions such as hydrogen bonding. Furthermore, XRD diffraction patterns indicated high lateral packing of molecular layers in oleogel prepared with the Sit and SA combination compared with oleogel prepared with a single gelator. On the other hand, for studying the effect of varying concentrations of gelator combinations, the Sit3:SA2 (w/w) combination was added to SFO at concentrations of 10, 15, 20, 25, and 30 g/100 g oil. Specific characteristics such as the oil‐binding capacity and firmness of the oleogel improved as the concentration of the gelator combination (Sit3:SA2) increased from 10 up to 30 g/100 g oil. Therefore, it can be concluded that the saturated fat alternative oleogel can be prepared from SFO with a specific Sit and SA combination ratio and concentration.     

Physical Properties of Soybean Oleogels and Oil Migration Evaluation in Model Praline System

The present study examined the physical properties of soybean oleogels and commercial confectionery filling fats and evaluated the oil migration properties in model praline systems. Soybean oleogels were prepared using different oleogelators namely monoglyceride (MAG oleogels) and a mixture of sorbitan tri‐stearate (STS) with lecithin (50:50) (Lec‐STS oleogels). Both MAG oleogels and Lec‐STS oleogels demonstrated a flat solid fat content (SFC) profile with zero SFC at 40 °C. At low temperature, MAG oleogels and Lec‐STS oleogels demonstrated a non‐flowing gel‐like property due to the ability of the oleogelator to entrap liquid oil. In addition, oleogels also showed thixotropic behavior indicating the possible capability to prevent migration of filling fats to coatings and also good flow ability during pumping though manufacturing equipment. The textural property of oleogels also did not change significantly upon storage indicating good structural stability. When used as in a model praline system, oleogels demonstrated a migration delaying property.     

Catalytic transesterification of corn oil and tristearin using immobilized lipases from Thermomyces lanuginosa

Thermomyces lanuginosa lipase was employed to catalyze the interesterification reaction between corn oil and tristearin at 45°C in a solvent-free system. HPLC and GC analyses were used to monitor both the distribution of TAG and the concentrations of MAG, DAG, and TAG as the reaction progressed. The positional distribution of the FA residues in the interesterified product was also determined for comparison to that of the original corn oil. Two different weight ratios of corn oil to tristearin were studied. Addition of molecular sieves to the reaction medium reduced the percentage of hydrolysis from 15 to 7. In order to improve the results obtained with Lipozyme TL IM, an immobilization of T. lanuginosa lipase was carried out. At a solids loading of 10% (w/w), the new immobilized lipase reduced the concentration of tristearin from 6 to 0.5% in only 30 min.