Quality of Brazilian vegetable oils evaluated by (modulated) differential scanning calorimetry

Vegetable oils are increasingly replacing fossil-oil-based polymers, and therefore aimed at being used in polymerization reactions from ?20 to 100?°C. Therefore, phase transitions and heat capacities in this temperature range should be well characterized to optimize processing conditions and energy inputs. By using the DSC analysis, only small primary correspondence or divergence between different oil types are seen as a function of their degree of unsaturation, but it does not clearly distinguish detailed features such as shoulder bands related to the separate melting processes of single fatty acid components. By using modulated DSC analysis, the combined analysis of reversing and non-reversing heat signals provides better results. The latter confirms that the melting is not a physical one-step process, but equilibrates between phase transitions and enthalpic reorganizations of the fatty acids that can be monitored separately. The specific heat capacities measured during modulated DSC are somewhat lower than traditional calorimetric measurements, but relate to the degree of unsaturation. The thermal behavior of palm-, soy-, sunflower-, corn-, castor-, and rapeseed-oil is discussed in relation to their composition, by applying a first or second heating scan.     

Screening and Production Study of Microbial Xylanase Producers from Brazilian Cerrado

Hemicelluloses are polysaccharides of low molecular weight containing 100 to 200 glycosidic residues. In plants, the xylans or the hemicelluloses are situated between the lignin and the collection of cellulose fibers underneath. The xylan is the most common hemicellulosic polysaccharide in cell walls of land plants, comprising a backbone of xylose residues linked by β-1,4-glycosidic bonds. So, xylanolytic enzymes from microorganism have attracted a great deal of attention in the last decade, particularly because of their biotechnological characteristics in various industrial processes, related to food, feed, ethanol, pulp, and paper industries. A microbial screening of xylanase producer was carried out in Brazilian Cerrado area in Selviria city, Mato Grosso do Sul State, Brazil. About 50 bacterial strains and 15 fungal strains were isolated from soil sample at 35 °C. Between these isolated microorganisms, a bacterium Lysinibacillus sp. and a fungus Neosartorya spinosa as good xylanase producers were identified. Based on identification processes, Lysinibacillus sp. is a new species and the xylanase production by this bacterial genus was not reported yet. Similarly, it has not reported about xylanase production from N. spinosa. The bacterial strain P5B1 identified as Lysinibacillus sp. was cultivated on submerged fermentation using as substrate xylan, wheat bran, corn straw, corncob, and sugar cane bagasse. Corn straw and wheat bran show a good xylanase activity after 72 h of fermentation. A fungus identified as N. spinosa (strain P2D16) was cultivated on solid-state fermentation using as substrate source wheat bran, wheat bran plus sawdust, corn straw, corncob, cassava bran, and sugar cane bagasse. Wheat bran and corncobs show the better xylanase production after 72 h of fermentation. Both crude xylanases were characterized and a bacterial xylanase shows optimum pH for enzyme activity at 6.0, whereas a fungal xylanase has optimum pH at 5.0–5.5. They were stable in the pH range 5.0–10.0 and 5.5–8.5 for bacterial and fungal xylanase, respectively. The optimum temperatures were 55C and 60 °C for bacterial and fungal xylanase, respectively, and they were thermally stable up to 50 °C.     

Thermoplastic starch films: DOE and O2PLS methodology for optimization and increased understanding of polymer processing

The combined effect of a plasticiser (glycerol) and a cross-linking agent (borax) on the mechanical properties of commercially extruded thermoplastic hydroxypropylated starch films was examined. The use of Design of Experiment (DOE) was demonstrated and used to predict and optimise formulations for a given set of material properties. As an extension to DOE, Orthogonal 2 Partial Least Squares (O2PLS) provided insight into joint correlations between the machine and transverse direction mechanical properties. Specific information regarding individual measurements or samples was also obtained with this analysis. O2PLS identified unique variables in individual compositions that were potentially incorrect measurements, or processing defects, which in turn can be used to aid quality control or processing optimisation with regards to DOE. Overall, DOE and O2PLS showed that within a starch borax-glycerol blend, borax increased mechanical strength and enhanced creep and recovery, whilst glycerol increased elongation and decreased modulus. There were competing interactions between the two dependent on concentration, and variation between machine and transverse properties was due to the extrusion induced molecular orientation of amylose. The optimum concentrations of borax and glycerol needed to achieve higher elongation, tensile strength, modulus and creep recovery than a control was found to be approximately 0.5% and 10%, respectively.     

Thermoplastic starch blends: A review of recent works

The aim of this review is to discuss the recent developments in thermoplastic starch blends. Starch has been considered as an excellent candidate to partially substitute synthetic polymer in packaging, agricultural mulch and other low-cost applications. Recently, the starch granules were plasticized using different plasticizers under heating and shearing, giving rise to a continues phase in the form of a viscous melt which can be processed using traditional plastic processing techniques, such as injection molding and extrusion. This kind of starch composites is called thermoplastic starch. Unfortunately, thermoplastic starch presents some drawbacks, such as low degradation temperatures, which make it difficult to process, poor mechanical properties and high water susceptibility. Much work has been carried out to overcome these drawbacks, including the combination of thermoplastic starch with other polymers, aiming at lowering the cost and enhancing the biodegradability of the final product.     

Solubility of light fullerenes in vegetable oils

Polythermal (in the temperature range 0−80°C) solubility of light fullerenes (C₆₀ and C₇₀), and also of fullerene mixtures (65% C₆₀, 34% C₇₀, and 1% C_76–90) in vegetable oils (of unrefined and refined sunflower, corn, olive, linen, apricot, grape, cedar, and walnut) was studied; the corresponding solubility polytherms are given and characterized.     

Differentiation of vegetable oils by mass spectrometry combined with statistical analysis

The main triacylglycerol (TAG) composition of different plant oils (almond, avocado, corn germ, grape seed, linseed, mustard seed, olive, peanut, pumpkin seed, sesame seed, soybean, sunflower, walnut and wheat germ) were analyzed using two different mass spectrometric techniques: HPLC/APCI-MS (high-performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry) and MALDI-TOFMS (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry).Linear discriminant analysis (LDA) as a multivariate mathematical statistical method was successfully used to distinguish different plant oils based on their relative TAG composition. With LDA analysis of either APCI-MS or MALDI-MS data, the classification among the almond, avocado, grape seed, linseed, mustard seed, olive, sesame seed and soybean oil samples was 100% correct. In both cases only 6 different oil samples from a total of 73 were not classified correctly.     

电感耦合等离子体发射光谱法测定植物油中的磷

用电感耦合等离子体发射光谱法(ICP-AES)测定了植物油中的磷.采用多谱线拟合技术(MSF)校正了铜对P213.617 nm和P214.914 nm光谱干扰.比较了活性炭炭化灰化法和微波消解法两种样品前处理方法对分析结果的影响.结果表明这两种前处理方法所得结果都能与国标磷钼蓝分光光度法的分析结果吻合,其中活性炭炭化灰化法的方法检出限(0.053 mg/kg)较微波消解法的方法检出限(0.42 mg/kg)更低,所以对低含量的磷的检测结果其相对误差及精密度更好.该法应用于植物油中磷的测定.     

Chromatographic analysis of minor constituents in vegetable oils

The main group of minor constituents belonging to vegetable oils are reviewed. Their importance in the characterization, origin and detection of oil mixtures are considered. Also, the determination of these minor components is of great value in establishing the oil quality and their genuineness. The most commonly used procedures (including the Official methodologies) normally applying chromatographic techniques are reviewed. The interference of each component within the determination of the other minor constituents are discussed. Furthermore, novel procedures for determining those compounds are also presented.     

Cytotoxicity of active ingredients extracted from plants of the Brazilian "Cerrado"

Cytotoxicity assays are needed for the screening of natural products with potential anti-inflammatory. The purpose of this study was to compare the basal cytotoxicity of active ingredients extracted from plants of the Brazilian "cerrado". The viability was assayed with the neutral red uptake assay in Mac Coy cells after 24h of exposition. The dose evaluated was 50 microg/microL. The test substances were: cinnamic acid, p-coumaric acid, chlorogenic acid, syringic acid, vannilic acid, homogentisic acid, scandenin, palustric acid, diosgenin, cabraleone. Studies of cytotoxicity demonstrated that all active compounds evaluated have low toxicity in vitro. The substances showed cell viability above 60% for the concentration used. However, the cinnamic acid, sacandenin and palustric acid showed highest toxicity with a 50% reduction in cell viability for the dose of 50 microg/microL. Cytotoxic screening results are useful to estimate the best concentrations of those compounds with potential anti-inflammatory without their cause cell death.     

Application of vegetable oils for electrocatalytic synthesis of hydrocarbons

Conditions of Kolbe cross-electrosynthesis of 10-undecylenic and acetic acids are studied on different catalyst anodes. It is shown that the key anodic process stages are the stages of formation of vinyl radicals from anions of unsaturated and methyl radicals under electrosynthesis of acetate anions. As dependent on the conditions of the process, the main product formed on the anode of the Pt-10% Ir alloy is either hydrocarbon CH₃CH₂CH(CH₃)(CH₂)7CH₂CH₃ (58 wt %) being the product of addition of three methyl radicals to a vinyl radicals or olefin CH₂=CH(CH₂)₇CH₂CH₃ (57 wt %) being the product of dimerization of vinyl and methyl radicals.     

植物油中邻苯二甲酸酯类化合物的一步萃取方法

为实现植物油中邻苯二甲酸酯（PAEs）的现场快速检测,建立了气液微萃取（GLME）技术并与GC-MS检测技术联用实现了植物油中PAEs的一步萃取检测。GLME方法在气流吹扫-微注射器萃取技术的基础上建立而成。此方法定量取0.1 g植物油样品,利用GLME在5 min内完成PAEs的萃取、净化和浓缩,结合内标法确保了结果的准确性。在大豆油、调和油、橄榄油、香油等4种样品中添加200 μg/kg的15种PAEs,基质加标回收率为60.0%~112.3%,相对标准偏差（RSD）为0.9%~28.4%。该法操作简单、方便,准确度高,重现性好,基质干扰少,适用于现场检测和快速检测,对于保障我国食品安全、构建完整的食品安全检测体系具有重大意义。     

Thermochemistry of methyl and ethyl esters from vegetable oils

This paper deals with the gas‐phase thermodynamic properties of methyl ester and ethyl ester of vegetable oils (fatty acid methyl esters and fatty acid ethyl esters respectively) present in biodiesel. The standard enthalpies of formation at 298.15 K, heat capacities, and entropies in the temperature range 300–5000 K are determined by means of quantum chemistry calculations along with a protocol developed for these compounds. The resultant data, currently not available in the literature for most of them, are critical to the modeling of combustion chemistry of the subject compounds. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 481–491, 2007     

Classification of edible vegetable oils using square wave voltammetry with multivariate data analysis

This paper proposes a simple and non-expensive electroanalytical methodology for classification of edible vegetable oils with respect to type (canola, sunflower, corn and soybean) and conservation state (expired and non-expired shelf life). The proposed methodology employs an alcoholic extraction procedure followed by square wave voltammetry (SWV). Two chemometric methods were compared for classification of the resulting voltammograms, namely Soft Independent Modelling of Class Analogy (SIMCA) and Linear Discriminant Analysis (LDA) with variable selection by the Successive Projections Algorithm (SPA). The results were evaluated in terms of errors in a set of samples not included in the modelling process. The best results were obtained with the SPA-LDA method, which correctly classified all samples in terms of type and conservation state.     

Evaluation of oxidative stability of vegetable oils enriched with herb extracts by EPR spectroscopy

Vegetable oils are important constituents of a healthy diet. Still, unsaturated fatty acids present in vegetable oils are susceptible to oxidation, which leads to undesirable changes in sensory, chemical and nutritional properties of oils. To prevent this problem, antioxidants are applied with herbs and spices being one of the most important sources of natural antioxidants. Electron paramagnetic resonance spectroscopy (EPR) can be used to detect free radicals, which are the short-lived intermediates of lipid oxidation, and to monitor changes in oxidation susceptibility. In this study, the ESR spin trapping technique was used as a potential method for the evaluation of the resistance to free radical formation in rapeseed and sunflower oils enriched with herb extracts. The antioxidant effect of herb extracts on vegetable oils was also investigated by measuring their ability to scavenge DPPH free radical using EPR spectroscopy. The herb extracts generally improved the radical scavenging properties of sunflower and rapeseed oils but their influence on the onset of rapid lipid oxidation as measured by spin-trapping EPR depended on the type of oil and on the extract concentration.     

Decolorization of vegetable oils: chlorophyll-a adsorption by acid-activated sepiolite

The adsorption characteristics of acid activated sepiolite (AAS) for the removal of chlorophyll-a (C(55)H(72)MgN(4)O(5)) from rapeseed oil was studied as a function of different sepiolite dosages and bleaching temperatures. A correlation has been shown between the adsorption capacity and a combination of AAS amount, bleaching temperature and oxidative reactions of chlorophyll-a. The adsorption equilibrium was found to follow the Langmuir isotherm model with a maximum adsorption capacity of 0.36 mg/g on AAS and K(L) value ranging from 6.11 to 19.51 kg/mg at 80 and 100 degrees C. It was found that AAS is an effective sorbent for the removal of chlorophyll-a molecule which is believed to adsorb as a protonated species onto SiOH groups at the edge in the tetrahedral sheet of sepiolite. These findings reveal that chlorophyll-a molecules not only adsorb onto the external surface of AAS but replace the released Mg(2+) ions in the octahedral sheet; they, depending on the pore size of AAS, are also incorporated in the channels and tunnels of sepiolite. A structural model is proposed to account for the orientation of chlorophyll-a in the sepiolite matrix.