MONITORING OF TRANSESTERIFICATION OF PALM OIL BY DIFFERENTIAL SCANNING CALORIMETRY

Chemical transesterification was conducted to obtain triacylglycerol ( TG) containing maximum concentrations of trisaturated and triunsaturated TG in palm oil. Catalyst (sodium methoxide) concentration of 0.1–0.5%, reaction temperature of 50–92C and reaction time of 30–480 min were applied in 20 treatments. Concentrations of trisaturated and triunsaturated TG, as well as melting points and iodine values were monitored by differential scanning calorimetric (DSC) techniques. The results showed that maximum trisaturated and triunsaturated TG achieved for refined-bleached-deodorized (RBD) palm oil were 17.10 and 7.50%, respectively, using 0.42% catalyst, at 58C in 389 min. These amounts were higher compared to control (untransesterified) RBD palm oil i.e 7.45 and 4.92%, respectively. The melting points of the products were higher compared to the control, while the iodine values were not significantly changed in all of the treatments.     

RANDOMNESS TEST OF FATTY ACIDS DISTRIBUTION IN TRIACYLGLYCEROL MOLECULES OF PALM OIL

For food purposes, the palm oil is generally fractionated to solid (stearin) and liquid (olein) fractions. Distribution of fatty acids in triacylglycerols of palm oil determines the fate of fractionation in terms of yield and quality of the products, specifically the liquid fraction or olein. The more trisaturated and triunsaturated and the less mono- and disaturated will yield higher and better quality olein. There are six types of fatty acids found in the palm oil, but only 14 combinations are found in the triacylglycerols. In this study, such combinations were statistically tested to determine whether or not the fatty acids are randomly distributed, and if it was not, toward which direction the regulatory agent works. The distribution of fatty acids in the palm oil triacylglycerols was found to be nonrandomly distributed. Unfortunately, the palm tended to form 11.98% higher disaturated triacylglycerols, −7.4% less triunsaturated, and −4.25% less trisaturated compared to when the arrangement was random. If manipulation could be induced in such a way that the synthesis of triacylglycerols becomes random, the triunsaturated and trisaturated triacylglycerol proportion expectedly would increased to 12.57% and 12.43%, respectively. Such manipulation can be done in the plant through genetic engineering, or in the harvestedpuit through application of stimulant, or in the oil through chemical or enzymatic transesterification.     

Lipase-catalysed interesterification between canola oil and fully hydrogenated canola oil in contact with supercritical carbon dioxide

The processing parameters in enzymatic reactions using CO₂-expanded (CX) lipids have strong effects on the physical properties of liquid phase, degree of interesterification, and physicochemical properties of the final reaction products. CX-canola oil and fully hydrogenated canola oil (FHCO) were interesterified using Lipozyme TL IM in a high pressure stirred batch reactor. The effects of immobilised enzyme load, pressure, substrate ratio and reaction time on the formation of mixed triacylglycerols (TG) from trisaturated and triunsaturated TG were investigated. The optimal immobilised enzyme load, pressure, substrate ratio and time for the degree of interesterification to reach the highest equilibrium state were 6% (w/v) of initial substrates, 10 MPa, blend with 30% (w/w) of FHCO and 2 h, respectively. The physicochemical properties of the initial blend and interesterified products with different FHCO ratios obtained at optimal reaction conditions were determined in terms of TG composition, thermal behaviour and solid fat content (SFC). The amounts of saturated and triunsaturated TG decreased while the amounts of mixed TG increased as a result of interesterification. Thus, the interesterified product had a lower melting point, and broader melting and plasticity ranges compared to the initial blends. These findings are important for better understanding of CX-lipid reactions and for optimal formulation of base-stocks of margarine and confectionary fats to meet industry demands.     

高温气相色谱法分析油脂随机酯交换反应程度研究

以大豆油和极度氢化棕榈油为原料进行酯交换反应,利用高温气相色谱法分析反应前后各种三酰甘油组成的变化,研究了不同催化剂催化酯交换反应的酯交换率,从而评判催化剂催化效果。采用此方法,利用单因素试验对Lipozyme 435脂肪酶催化大豆油与极度氢化棕榈油酯交换的参数进行了研究,得到适合的反应条件为:反应温度90℃、反应时间4 h、加酶量4%(占油脂总质量)、大豆油与氢化棕榈油质量比4∶3。在此条件下反应随机酯交换率为98.3%。     

Structured lipids obtained by chemical interesterification of olive oil and palm stearin

Interesterification of palm stearin (PS) with liquid vegetable oils could yield a good solid fat stock that may impart desirable physical properties, because PS is a useful source of vegetable hard fat, providing β′ stable solid fats. Dietary ingestion of olive oil (OO) has been reported to have physiological benefits such as lowering serum cholesterol levels. Fat blends, formulated by binary blends of palm stearin and olive oil in different ratios, were subjected to chemical interesterification with sodium methoxide. The original and interesterified blends were examined for fatty acid and triacylglycerol composition, melting point, solid fat content (SFC) and consistency. Interesterification caused rearrangement of triacylglycerol species, reduction of trisaturated and triunsaturated triacylglycerols content and increase in diunsaturated-monosaturated triacylglycerols of all blends, resulting in lowering of melting point and solid fat content. The incorporation of OO to PS reduced consistency, producing more plastic blends. The mixture and chemical interesterification allowed obtaining fats with various degrees of plasticity, increasing the possibilities for the commercial use of palm stearin and olive oil.     

DEVELOPMENT OF DEEP FRYING EDIBLE VEGETABLE OILS

Refined soybean and rice-bran oils have been selected as base oils for preparation of frying oils. Hexane and acetone fractionation of nontraditional tree seed oils (NTOs) such as sal, mango, mahua and palm fats was carried out at 5–20C. Chemical and chromatographic parameteres were used to fractionate each oil (NTOs) in order to obtain olein-rich and stearin-rich fractions. The stearin fraction obtained at 10 and 15C from hexane and acetone were identical and hence mixed together. The stearin fraction obtained from all the four NTOs were incorporated at 10% level with the conventionally refined (market sample) and physically refined (laboratory sample) soybean and rice-bran oils in order to obtain frying oils. Heat stability parameters of the oils, namely free fatty acids (FFA%), peroxide value (PV), and iodine value (IV) were determined for base oils and frying oils after heating. Values for oil samples changed as follows: A (refined soybean oil and frying oils containing it) % FFA from 0.18 to 0.17–0.19, PV from 3.6 to 4.6–6.0 and IV from 125.3 to 109.2–115.8; B (refined rice-bran oil and frying oils containing it) from 0.21 to 0.19–0.23 for % FFA, 4.0 to 4.6–6.7 for PV and 99.4 to 87.6–92.8 for IV; C (physical refined soybean oil and frying oils containing it) from 0.36 to 0.33–0.36 for % FFA, 5.7 to 7.4–11.2 for PV and 126.9 to 108.9–113.2 for IV; and D (physical refined rice bran oil and frying oils containing it) from 0.79 to 0.75–0.79 for % FFA, 7.1 to 8.2–11.3 for PV and 101.4 to 88.6–93.7 for IV, respectively. However, when base oils were heated as such, their deterioration was much faster. Fatty acid composition, determined by gas chromatography, also supported the results obtained by chemical means. These frying oils showed improved heat stability compared to their base oils.     

SUPERIOR OXIDATIVE STABILITY OF DOCOSAHEXAENOIC ACID-ENRICHED OILS IN THE FORM OF PHOSPHOLIPIDS

Oxidative stabilities of docosahexaenoic acid (DHA, 22:6 n-3)-enriched oils (7.0 – 7.1 mol% of total fatty acids), in the form of phospholipids (PL), triacylglycerols (TG) and ethyl esters (EE), were comparatively investigated with those of control oil (palm oil supplemented with 20% soybean oil; containing no DHA). Autoxidation of sample oil (50 mg) was performed in a 10 mL glass vial at 25C for 42 days in the dark. During the oxidation, headspace oxygen absorption was significantly lower in oil in the form of PL than TG and EE, and was almost equivalent to that of control oil. At day 42 of oxidation, peroxide value and carbonyl value of PL were lower than those of TG and EE. The change of constituent fatty acids during the oxidation was larger in TG and EE than PL. The results indicated that DHA-enriched oils in the form of PL are more stable to autoxidation than those in the form of TG and EE.     

过氧甲酸法环氧棕榈油的制备研究

采用过氧甲酸法制备环氧棕榈油,研究了甲酸、双氧水、催化剂用量以及反应温度、反应时间对环氧值的影响.并通过响应面法对工艺条件进行优化,得到最佳反应条件为:m(棕榈油)∶ m(甲酸)∶ m(30%双氧水)∶ m(催化剂)=30∶ 6∶ 43∶ 0.3,反应温度65 ℃,反应时间6 h.在此条件下产品环氧值为3.89%.     

超临界CO_2状态下米糠油加氢反应的研究

在CO2超临界状态下,采用Pd/C做催化剂,对三级米糠油进行氢化反应研究,确定了最佳工艺条件:催化剂用量0.07%,反应时间40 min,温度75℃,总压力7.5 MPa,搅拌速度200 r/min。在此条件下,所得氢化米糠油的碘值为53.2 g/100 g,产品颜色为乳白色,免去了油脂脱色步骤,保留了原有的营养物质,成品中反式脂肪酸含量低,使其成为优质的人造奶油基料。     

RECOVERY OF PALM CAROTENE FROM PALM OIL AND HYDROLYZED PALM OIL BY ADSORPTION COLUMN CHROMATOGRAPHY

Crude palm oil and crude palm olein were hydrolyzed with lipase from Candida rugosa to produce a free fatty acid (FFA) rich oil. The percentages of FFA produced and carotene degradation after the hydrolysis process were determined. The palm oil and hydrolyzed palm oil were subsequently subjected to column chromatography. Diaion HP-20 adsorbent was used for reverse phase column chromatography at 50C. Isopropanol or ethanol, and n-hexane were used as the first and second eluting solvents, respectively. The objective of hydrolyzing the palm oil was to produce more polar FFA-rich oil in order to enhance the nonpolar carotene bind to the nonpolar HP-20 adsorbent in the column chromatography process. Hydrolyzing palm oil with lipase from Candida rugosa gave 30- and 60-fold, respectively, of FFA in the crude palm oil and crude palm olein in 24 h at 50C. Approximately, 15.56 and 17.48% of carotene degraded in crude palm oil and crude palm olein, respectively. For column chromatography, using isopropanol or ethanol as the first eluting solvent, unhydrolyzed oil and hydrolyzed oil showed the carotene recovery infraction two (carotene-rich fraction) of about 36–37 and 90–96%, respectively. Over 90% of carotene recovery was obtained from     

Chemical interesterification of milkfat and milkfat-corn oil blends

Blending and chemical interesterification of fats have been used to modify physical and chemical properties of natural fats. The objective of this study was to produce binary mixtures of butterfat and corn oil that serve as a base for a tablespread, keeping the desirable organoleptic qualities of butter, yet with higher contents of ω-6 fatty acids. Chemical interesterification was performed to improve butter’s physical properties, such as better spreadability. Liquefied butterfat and corn oil were mixed in different proportions and then chemically interesterified. Butterfat consisted of 66.5% saturated fatty acids, with palmitic acid being predominant. Corn oil had more than 50% of linoleic acid in its composition. Interesterification significantly reduced trisaturated and triunsaturated triacylglycerol contents and increased softening points in all blends. The negative coefficients of the blends from multiple regression of the solid fat content revealed a monotectic interaction between butterfat and corn oil in temperatures ranging from 10 to 35 °C, before and after interesterification.     

LIPASE-CATALYZED ACIDOLYSIS OF ALGAL OILS WITH CAPRIC ACID: OPTIMIZATION OF REACTION CONDITIONS USING RESPONSE SURFACE METHODOLGY

Lipase-assisted acidolysis of algal oils, arachidoinc acid single cell oil (ARASCO), docosahexaenoic acid single cell oil (DHASCO) and a single cell oil rich in both docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA, n-6) known as OMEGA-GOLD, with a medium-chain fatty acid (capric acid) was studied. Response surface methodology was used to obtain a maximum incorporation of CA into algal oils. The process variables studied were the amount of enzyme (2–6%), reaction temperature (35–55C) and incubation time (12–36 h). The amount of water added and mole ratio of substrate (algal oil to CA) were kept at 2% and 1:3, respectively. All experiments were conducted according to a face-centered cube design. Under optimum conditions (12.3% of enzyme; 45C; 29.4 h), the incorporation of CA was 20.0% into ARASCO, 22.6% into DHASCO (4.2% enzyme; 43.3C; 27.I h) and 20.7% into the OMEGA-GOLD oil (2.5% enzyme, 46.6C; 25.2 h).     

INTERESTERIFICATION KINETICS OF SOYBEAN OIL

Soybean oil was interesterified at different temperatures, ranging from 10 to 80 C, 600 rpm stirring rate and 0.2–0.5% catalyst (NaOCH₃) concentration. The content of palmitic acid in the 2-position of triacylglycerols was monitored during the reaction by an enzymatic method. The conversion of triacylglycerols to random distribution appeared to be a first order and reaction rate constants (k) were determined between 0.015 and 1.498 min^-1. It was also observed that reaction rate increased about 8 times when catalyst ratio was increased from 0.2 to 0.5% and about 10 times when temperature was raised from 40 to 80C. Activation energy was calculated as 14188 Cal/mole, from plotting of Lnk values against reciprocal of absolute temperature.     

PREPARATION OF TOCOPHEROL SUCCINATES FROM DEODORIZER DISTILLATE

Preparation of tocopherol succinates from deodorizer distillate (DOD) with or without pretreatment was studied. To reduce damage to tocopherols, the reaction mixture was purged with nitrogen during heating. For DOD as a raw material, the succinylation procedure for converting tocopherols to tocopherol succinates was optimized in terms of type of catalyst, reaction time, and reaction temperature. Potassium acetate performed best among the catalysts tested. Using potassium acetate, 90% conversion was achieved within 30 min for total tocopherols and within 90 min for α-tocopherol. The optimal reaction time ranged from 60 to 90 min. To obtain rapid reaction and high conversion, the suitable temperature range was 100–140C. Under optimal conditions, a conversion of 93% was reached. For sterol-removed DOD as a raw material, the succinylation reaction was carried out at 140C for 1 h using potassium acetate as a catalyst. When using 10% of succinic anhydride and 1.3% of catalyst, over 80% of total tocopherols were converted to tocopherol succinates with conversion of α-tocopherol being highest among all isomers (over 90%). The conversion was significantly increased to over 90% by increasing the amount of succinic anhydride from 10 to 13% and that of the catalyst from 1.3 to 2%. Meanwhile, the free fatty acid (FFA) content was increased to approximately 10% after the succinylation reaction.     

Triglyceride composition of Buchanania lanzan seed oil

The fatty acid composition of Buchanania lanzan seed oil, determined by urea complex formation and gas liquid chromatography (g.l.c), was found to be: myristic, 0.6; palmitic, 33.4; stearic, 6.3; oleic, 53.7; and linoleic, 6.0%. Triglyceride compositions of the native seed oil and its randomised product were calculated from the fatty acid compositions of the triglycerides and of the corresponding 2-monoglycerides produced by pancreatic lipase hydrolysis. The oil is composed of 3.2, 35.8, 45.5 and 15.5% trisaturated, monounsaturated disaturated, diunsaturated monosaturated and triunsaturated glycerides respectively. The special characteristic of the B. lanzan seed oil is its content of 22.7, 31.0 and 11.3% dipalmitoolein, dioleopalmitin and triolein respectively. The percent GS₃ content in the oil increased from 3.2 to 7.5 by the process of randomisation. On directed interesterification the oil yielded a product with a slip point of 41.5°C which may be suitable as a coating material for delayed action tablets. The oil also appears to be a promising one as a commercial source of palmitic and oleic acids.     

氢氧化钠与甘油催化棕榈基油脂酯交换反应

利用氢氧化钠与甘油催化棕榈液油和棕榈硬脂进行酯交换反应,考察反应温度、氢氧化钠浓度、反应时间、氢氧化钠与甘油比例、搅拌速度对反应产物固体脂肪含量、甘油三酯碳数、酸值、皂化值、熔点的影响。结果表明:在反应温度110℃、反应时间30 min,氢氧化钠浓度0.5%、氢氧化钠与甘油的比例1︰1、搅拌速度150 r/min的条件下,氢氧化钠与甘油混合物的催化效果接近于甲醇钠。     

Antioxidant effect of Cassia essential oil on deep-fried beef during the frying process

The object of the research was to determine the antioxidant effect of cassia essential oil on deep-fried beef during the frying process. The rules and optimum processing conditions of deep-fried beef with addition of cassia essential oil were discussed through an orthogonal experiment and some single factor experiments (frying time, frying temperature, oil types and concentration of essential oil). The antioxidant effect was evaluated by peroxide and TBA value. Results showed that the antioxidant effect of cassia oil during the frying process was optimum under the conditions of 30 μL cassia oil/250 mL palm oil, 1.5 min at 150 °C. The main compositions of cassia oil were analysed by GC–MS method.     

Characterization of Low Saturation Palm Oil Products after Continuous Enzymatic Interesterification and Dry Fractionation

ABSTRACT:  The lipase-catalyzed interesterification of refined, bleached, deodorized palm olein with iodine value (IV) of 62 was studied in a pilot continuous packed-bed reactor operating at 65 °C. Sn- 1,3 specific immobilized enzyme; Lipozyme® TL IM ( Thermomyces Lanuginosa ) from Novozyme A/S was used in this study. The interesterification reaction produced fully solidified fats at ambient temperature due to the production of trisaturated triacylglycerols (TAG) (PPP and PPS, where P = palmitic acid, S = stearic acid). The reaction also increased the percentage of triunsaturated TAG (OLL, OLO, and OOO, where O = oleic acid, L = linoleic acid). The interesterified product was then dry fractionated at temperatures of 9, 12, 15, 18, and 21 °C to separate the saturated fats from the unsaturated. The results show that IV of olein increased when the fractionation temperature (T_FN) decreased. The highest IV of olein was 72, obtained from T_FN at 9 °C. After interesterification and laboratory-scale fractionation, the olein fractions contained higher unsaturation content ranging from 64.7% to 67.7% compared to the starting material (58.3%), while the saturation content was reduced from 41.7% to the range of 32.3% to 35.3%. The yields of these oleins were low with the range of 24.8% to 51.8% due to the limitation of the vacuum filtration. Ten kilograms of pilot-scale fractionation with membrane press filter was used to determine the exact olein yield. At T_FN of 12 °C, 67.1% of olein with saturation content of 33.9% was obtained.     

超声波和相转移催化剂在棕榈油皂化反应中的应用研究

以棕榈油为原料,对其非均相皂化反应进行了研究.对催化剂及皂化处理方式进行考察,并在此基础上选择反应温度、超声波功率、反应时间、催化剂添加量、KOH添加量进行了单因素优化实验.结果表明:相转移催化剂CTAB催化效果最好,超声波辅助搅拌处理方式最佳;单因素优化的最优皂化条件为反应温度70℃,超声波功率320 W,反应时间80 min,催化剂CTAB添加量0.5g(以每克油计),KOH添加量1.75 g(以每克油计).在最优条件下皂化率达到89.32％,是常规搅拌(无催化剂,无超声波作用)下皂化率的4.7倍,大大提高了效率.     

DEEP-FAT FRYING OF YAM SLICES: OPTIMIZATION OF PROCESSING CONDITIONS USING RESPONSE SURFACE METHODOLOGY

The deep-fat frying of yam slices was investigated with the aim of optimizing the processing conditions. During frying, frying temperature, initial dry matter and frying time have a significant effect on moisture loss and oil uptake. Response surface methodology central composite rotatable design was used to study the effects of the independent variables on quality attributes of yam chips. Breaking force, oil content, moisture content and color parameters were determined. Statistical analysis with response surface regression showed that breaking force, oil and moisture contents and color parameters ( L* and a* ) were significantly ( P <  0.05) correlated with frying temperature, initial dry matter and frying time. The optimum conditions were a frying temperature of 175–180C, using tubers of initial dry matter of 0.179–0.214 kg/kg with a frying time of 4–5 min. It was suggested that the regression equation can be used to estimate the dependent variables for fried yam chips except b* (yellowness) parameter.

PRACTICAL APPLICATIONS

It is expected that the optimized processing conditions highlighted in this work will be useful in obtaining fried yam chips of acceptable quality attributes. This optimized condition would be a good prospect for commercialization in small-scale industries.