Performance of palm olein in repeated deep frying and controlled heating processes

The stability of refined, bleached and deodorised (RBD) palm olein was studied under both repeated frying and controlled heating conditions. Two different frying foods i.e. chicken nuggets and French fries were used to evaluate the oil performance under various frying conditions. Thermo-oxidative alterations were measured through various physical and chemical parameters. Total polar compounds (TPC), polymeric triglycerides (PTG), blueness (b^∗ value), chroma (C^∗ value), refractive index and viscosity increased linearly with the number of frying/heating cycles. Palmitic acid content increased and linoleic acid content decreased linearly with the number of frying cycles. No significant changes in oleic acid were detected. Thermo-oxidative reactions induced under the heating conditions were found to be faster as compared to those under the frying conditions. The PTG formed at the end of heating cycles (16.42%) were substantially higher as compared to those formed at the end of frying French fries (9.72%) and chicken nuggets (5.34%).     

Lipase‐catalysed acidolysis of mango kernel fat with capric acid to obtain medium‐ and long‐chain triacylglycerols

Mango kernel fat (MKF) was blended with capric acid (1:5 mole ratio) and subjected to acidolysis using 1,3 specific lipase Lipozyme IM (Mucor miehei) for different time intervals (30 min to 24 h). The capric acid content increased gradually up to 43.5 mol% with corresponding decrease in stearic acid content (45.7–17.4 mol%). DSC crystallisation thermograms showed a new exothermic peak at lower temperature, and HPLC profile showed new peaks both indicating the formation of new lower melting triglycerides. A decrease in higher melting triglycerides and gradual increase in new triglycerides was observed. Two prominent newly formed triglycerides were characterised by ESI/MS studies and identified as 2‐oleo‐dicaprin (10, 18′, 10) and stearo‐oleo‐caprin (18, 18′, 10). Solid fat content decreased at all temperatures and samples interesterified for 5 h remained liquid at ambient conditions. The modified MKF can increase the food application from MKF in addition to contributing to health benefits of medium‐ and long‐chain triglycerides.     

微波消解-ICP-MS法测定中链甘油三酸酯中铜、铅、铬、镍、锡

为满足国家药品安全的限量要求,采用微波消解法对中链甘油三酸酯（MCT）进行前处理,建立了电感耦合等离子体质谱（ICP-MS）测定MCT中痕量有害元素铜、铅、铬、镍、锡的方法,并对测定条件进行了优化。结果表明：各元素在0～30 μg/L范围内线性良好,相关系数r在0.999 4～0.999 9之间,方法检出限为0.013～0.057 μg/kg,相对标准偏差为1.2%～6.7%;对各元素进行3个不同浓度水平下的加标回收率实验,平均回收率为94.0%～110.0%。使用该方法测定国家标准物质鸡肉GBW10018中的痕量有害元素,测定结果与标准值无显著差异。     

Structuring of 2-oleodipalmitin at the air interface from all-atom,united-atom,and coarse-grained molecular dynamics simulations

This study employs classical molecular dynamics (MD) simulations to investigate the behavior of 1,3-dipalmitoyl-2-oleoyl glycerol (POP), a typical triglyceride found in food at the air interface. The investigation utilizes three force fields (FF) with varying levels of detail, including all-atom, united-atom, and coarse-grained simulations, to elucidate the structural evolution of POP at the air interface. The results confirm that the structuring processes observed in nonfood triglyceride systems also occur in POP. Aliphatic chains orient toward the air phase, while glycerol backbones face the inner triglyceride phase. Additionally, the study observes the formation of clusters of glycerol head groups at the interface, and the choice of the FF significantly affects the simulated morphological structure. The Berger FF exhibits the most substantial structuring effects after 200 ns of simulation, followed by the General AMBER FF, while the Martini FF shows the weakest effects. Number density plots of aliphatic chains and glycerol backbones at different temperatures monitor the evolution of structuring effects over time and determine the approach toward equilibrium conditions. The temperatures investigated include the solid state of POP at ambient temperature (293 K), the liquid state at human body temperature (310 K), and a typical processing temperature of the chocolate conching process (333 K). Practical Applications: Tailored molecular design of interfaces according to their purpose in food.     

Lipase‐catalyzed production of biodiesel from rice bran oil

Biodiesel has attracted considerable attention as an alternative fuel during the past decades. The main hurdle to the commercialization of biodiesel is the cost of the raw material. Use of an inexpensive raw material such as rice bran oil is an attractive option to lower the cost of biodiesel. Two commercially available immobilized lipases, Novozym 435 and IM 60, were employed as catalyst for the reaction of rice bran oil and methanol. Novozym 435 was found to be more effective in catalyzing the methanolysis of rice bran oil. Methanolysis of refined rice bran oil and fatty acids (derived from rice bran oil) catalyzed by Novozym 435 (5% based on oil weight) can reach a conversion of over 98% in 6 h and 1 h, respectively. Methanolysis of rice bran oil with a free fatty acid content higher than 18% resulted in lower conversions (<68%). A two‐step lipase‐catalyzed methanolysis of rice bran oil was developed for the efficient conversion of both free fatty acid and acylglycerides into fatty acid methyl ester. More than 98% conversion can be obtained in 4–6 h depending on the relative proportion of free fatty acid and acylglycerides in the rice bran oil. Inactivation of lipase by phospholipids and other minor components was observed during the methanolysis of crude rice bran oil. Simultaneous dewaxing/degumming proved to be efficient in removing phospholipids and other minor components that inhibit lipase activity from crude rice bran oil. Copyright © 2005 Society of Chemical Industry     

Hydrogen,ethanol and cellulase production from pulp and paper primary sludge by fermentation with Clostridium thermocellum

Pulp and paper industry primary sludge being largely composed of lignocellulosic fibres, it could be used as carbon source by bacteria having cellulolytic capability. The aim of this study was to evaluate the use of cellulose contained in this type of sludge for Clostridium thermocellum to produce ethanol, hydrogen and cellulases. In an ATCC 1191 medium containing 5 kg m⁻³ dry primary sludge from recycled paper mill, batch culture reached stationary phase after 2 days. All of the available cellulose was hydrolysed after 60 h of incubation, with a final pH of 5.83. Metabolites produced after 60 h of fermentation were acetate (8.50 mol m⁻³), ethanol (11.30 mol m⁻³), lactate (8.75 mol m⁻³), formate (0.27 mol m⁻³), hydrogen (11.20 mol m⁻³) and carbon dioxide (18.41 mol m⁻³). Cellulase activity was detected in the supernatant after 36 h, with a maximal activity of 0.25 U cm⁻³ at 72 h. Pulp and paper primary sludge appeared to be a readily usable substrate for C. thermocellum at this concentration, yielding both potential biofuels (hydrogen and ethanol) as well as active cellulases.     

Crystallization kinetics of fully hydrogenated palm oil in sunflower oil mixtures

The crystallization kinetics of mixtures of fully hydrogenated palm oil (HP) in sunflower oil (SF) was studied. The thermal properties and phase behavior of this model system were characterized by means of differential scanning calorimetry and X-ray diffraction. From the melting enthalpy and clear point of HP, it was possible to calculate the supersaturation at a given temperature for every composition of the model system. Supersaturation of the model system for the β′ but not for the α polymorph yielded the β′ polymorph, while supersaturation for the α polymorph yielded a mixture of mainly β and some β′ polymorphs. The crystallization kinetics of HP/SF mixtures were determined by pulsed wide-line proton nuclear magnetic resonance for various initial supersaturations in the β′ polymorph. The determined curves were modeled by a modified classical nucleation model and an empirical crystal growth function, which are both functions of supersaturation. Heterogeneous nucleation rates in the β′ polymorph yielded a surface Gibbs energy for heterogeneous nucleus formation of 3.8 mJ·m⁻². About 80% of the triglyceride was assumed to be in a suitable conformation for incorporation in a nucleus. Induction times for isothermal crystallization in the β′ polymorph yielded a surface free energy for heterogeneous nucleus formation of 3.4 to 3.9 mJ·⁻².     

Production of Polyols from Canola Oil and their Chemical Identification and Physical Properties

The feasibility of a method based on ozonolysis and hydrogenation reactions for the production of polyols from unsaturated canola oil has been demonstrated. Polyol products with primary alcohol functional groups at position nine of each fatty acid ester in the original triacylglycerol have been produced from canola oil. Short straight-chain alcohols were also produced and were removed by wiped-blade molecular distillation. The pure components of the polyol, i.e. mono-ol, diol and triol were separated by flash chromatography, and identified by Fourier-transform infrared (FTIR), ¹H-nuclear magnetic resonance (NMR), ¹³C-NMR as well as mass spectrometry. Polyol identification was facilitated by the use of a simple high-performance liquid chromatography (HPLC) method to determine the composition of the polyol mixture, which can be exploited as a quality-control mechanism in designing novel polyol feedstocks. Basic correlations were established between the molecular diversity of the polyols and their physicochemical properties, such as hydroxyl number, acidity number, and viscosity. It has been found that the produced polyols are suitable for processing methods employing polyols for the production of polyurethanes and can be manipulated to create polyurethanes with desirable properties.