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Methyl or ethyl esters were produced from lard and restaurant grease by lipase-or base-catalyzed reactions. Before esterifying, some renewable substrates (lard and restaurant grease) should be manipulated through acetone fractionation or on a chromatography column packed with an adsorbent to obtain maximal reaction rate. Because lipase activity was hindered by excess amounts (more than 1 mol) of methanol, each 1 M methanol was added sequentially after 24 h of reaction. Through a three-step reaction, 74% conversion to tallow-methyl ester was obtained. However, a porous substance, such as silica gel, improved the conversion when more than 1 M methanol was used as reaction substrate. When a 1:3 (fractionated lard/methanol, mole ratio) substrate was used, the conversion rates (i.e., extent of conversion) were 2.7 (24 h) and 2.8% (48 h). However, with 10% silica gel in the reaction mixture, the conversion rates increased to 25 and 58%, respectively. Regenerated restaurant grease (FFA removed through column chromatography) was further converted to esters by alkali-catalyzed methanolysis. After 24 h of reaction, 96% conversion was obtained, while only 25% conversion was observed from crude grease. Alkyl esters produced in this study could be used for fuels, potentially as biodiesel.In the early 1930s, vegetable oils were tested on diesel engines as fuel. However, the high viscosity of vegetable oil, compared to petroleum-derived fuels, caused the engines to malperform, impeding their application as engine fuel. Nevertheless, concerns about petroleum shortages and environmental issues have continuously promoted the development of "alternative fuels" from vegetable oils, animal fats, and even restaurant grease (1-3).Monoalkyl esters of fats and oils are known as biodiesel (BD), which can be used as a blend with conventional petroleum fuels. Oils are esterified with alcohols (alcoholysis) to overcome the high-viscosity problem as engine fuel. In diesel engine performance and emission tests, a 20% blend of alkyl ester with No. 2 diesel fuel (BD-20) reduced emissions of particulate matter (−26.8%), carbon monoxide (−72.8%), and total unburned hydrocarbons (−73.2%) (4). Therefore, BD is one of the alternative fuels regarded as environmentally friendly.Lard is an inexpensive co-product of the meat-packing industry that could be further converted to value-added products such as BD. However, the relatively high contents of saturated fatty acids (SFA) in lard result in the poor coldtemperature properties of its alkyl ester. To improve coldtemperature properties, the content of SFA in lard could be reduced through a fractionation process before esterification. As a consequence of this procedure, BD from fractionated lard resists forming crystals at low temperatures, thus improving cold-temperature properties. Restaurant grease would be another renewable source for BD production. During cooking, especially deep-frying, oils are hydrolyzed into FFA and degraded by complex chemical reactions. As a result, abused cooking oils contain ...

Structured lipids (SL) were synthesized by the interesterification reaction between medium-chain triacylglycerols and eicosapentaenoic acid (EPA) ethyl ester. The products were partially purified, and the fatty acid at the sn-2 position was determined after pancreatic lipase-catalyzed hydrolysis. The effect of additives (water and glycerol) on the rate of reaction was also investigated. Mol% EPA incorporated into the triacylglycerols was increased by adding water when trilaurin and tricaprylin were the substrates and IM 60 was the biocatalyst. With SP 435, EPA incorporation was always less with additional water than without water. The addition of glycerol (0.005 g or 0.01 g) improved interesterification catalyzed by IM 60 to some degree, but an excess amount (0.02 g) inhibited the reaction. The reaction with glycerol showed no significant difference with SP 435. After scale-up and fractionation by column chromatography, we could recover approximately 0.3-0.4 g of product/g of reaction products. After hydrolysis by pancreatic lipase, we can conclude that IM 60 has a high specificity for sn-1,3 positions. With SP 435 lipase, 34.8-39.3 mol% of EPA was found at the sn-2 position of the recovered SL. JAOCS 73, 611-615 (1996).

Lipase-catalyzed interesterified solid fat was produced with fully hydrogenated soybean oil (FHSBO), and rapeseed oil (RSO) and palm stearin (PS) in a weight ratio of 15:20:65, 15:40:45 and 15:50:35. The interesterified fats contained palmitic (27.8-44.6%), stearic (15.6-16.2%), oleic (27.5-36.5%) and linoleic acids (8.0-13.5%). After interesterification of the blends, the physical properties of the products changed and showed lower melting points and solid fat contents, different melting and crystallization behaviors as well as the formation of more stable crystals. The produced interesterified fats (FHSBO:RSO:PS 15:20:65, 15:40:45 and 15:50:35 blends) contained desirable crystal polymorphism (b 0 form) as determined by X-ray diffraction spectroscopy, a long plastic range with solid fat content of 51-63% at 10°C to 4-12% at 40°C, and melting points of 39 (15:50:35), 42 (15:50:45) and 45°C (15:20:65). However, a reduction in tocopherols (a and c) content and a reduced oxidative stability were observed in the interesterified fats. The physical properties of the interesterifed fats were influenced by the amount of PS, resulting in more hardness and higher solid fat contents for 15:20:65 than 15:40:45 and 15:50:35 blends. The present study suggested that the produced interesterified fats containing trans-free fatty acids could be used as alternatives to hydrogenated types of bakery shortenings.

A structured lipid (SL) was synthesized enzymatically from chicken fat by incorporating a medium-chain length fatty acid (caprylic acid) into chicken fat triacylglycerols. Carica papaya latex was used as the biocatalyst. The optimal substrate mole ratio found was 1:2 (chicken fat fatty acids/caprylic acid). At this ratio of reactants, the incorporation of caprylic acid (C 8:0 ) at 65ºC was 23.4 mol%, whereas at 55°C the incorporation of caprylic acid was 17.6 mol%. A packed-bed column bioreactor was designed for the synthesis of SL from chicken fat. In using ground crude C. papaya latex (a w < 0.1), 7.1 mol% of caprylic acid was incorporated into the chicken fat triacylglycerols after 117 min of reactor residence time. After purification of the SL, the acyl positional distribution of fatty acids on the glycerol backbone was determined by 13 C nuclear magnetic resonance (NMR) spectroscopy. From the NMR spectrum of the SL, it was determined that saturated fatty acyl residues at the 1,3-positions of the SL triacylglycerols increased to 62% over that of the starting chicken fat triacylglycerols, suggesting that caprylic acid was preferentially incorporated at the 1,3-positions. In addition, differential scanning calorimetry thermograms were obtained to compare the crystallization characteristics of the starting chicken fat with the SL prepared from it.

Structured lipids (SL) containing n-3 polyunsaturated (eicosapentaenoic or docosahexaenoic) and mediumchain (caprylic) fatty acids were synthesized in gram quantities and characterized. Tricaprylin was mixed with n-3-rich polyunsaturated fatty acids in a 1:2 molar ratio and transesterified by incubating at 55°C in hexane with SP 435 lipase (10% by wt of total substrates) in a 125-mL Erlenmeyer flask as the bioreactor. After several batches of reaction, the products were pooled and hexane was evaporated. Short-path distillation was used for purification of synthesized SL. The distillation conditions were 1.1 Torr and 170°C at a feed flow rate of 3 mL/min. Up to 240 g of SL was isolated and deacidified by alkaline extraction or ethanol-water solvents. The fatty acid profile, free fatty acid value, saponification number, iodine value, peroxide value, thiobarbituric acid, and conjugated diene contents were determined. Oxidation stability, with α-tocopherol as antioxidant, and the oxidative stability index were also determined. JAOCS 75, 495-499 (1998). KEY WORDS:Medium-chain triacylglycerol, oxidative stability index, n-3 polyunsaturated fatty acids, structured lipids, thiobarbituric acid. FIG. 3. Graphical determination of the induction period of SL, EPAX 5500 (fish oil TAG), and tricaprylin by a slope/change algorithm method. OSI values were converted to AOM values by the automated Omnion instrument. SL = structured lipids, OSI = oxidative stability index, AOM = active oxygen method, TAG = triacylglycerols.