A rapid screening technique for vegetable oil identity by sub-ambient DSC

Vegetable oils are widely used in the food industry. Labeling requirements have alerted the consuming public to the presence of vegetable oils and to the wide variety of oils used. Vegetable oils are selected commercially for their physical properties, price and availability, and many ingredient labels contain the ‘and/or’ clause reflecting the interchangeability of food grade vegetable oils.A ‘fingerprinting’ method has been developed utilizing the characteristic sub-ambient liquid—solid and solid—solid transitions of vegetable oils. The DSC was used in the temperature range 320 to 220 K. The cooling curves and their first derivatives were recorded for a pattern recognition library of pure vegetable oils, mixtures of oils, and oils present in standard cookie dough. This pattern library will serve as the basis for rapid verification of identity for vegetable oils, mixtures of oils and oils in commercially prepared food products.     

Solid-phase extraction-thin-layer chromatography-gas chromatography method for the detection of hazelnut oil in olive oils by determination of esterified sterols

The sterol composition of extra virgin olive oil is very characteristic and, thus, has become a helpful tool to detect adulterations with other vegetable oils. Special attention has been addressed to the separate determination of the free and esterified sterol fractions, since both have different compositions and can thus provide more precise information about the actual origin of the olive oil. In the case of admixtures with small amounts of hazelnut oil, this approach can be extremely useful, because the similarity between the fatty acid compositions of both oils hampers the detection of the fraud. A hyphenated chromatographic method was developed for a sensitive and precise determination of esterified sterols in olive oils. The oil was subjected to silica solid-phase extraction (SPE) fractionation, cold saponification of the collected fraction and purification on silica TLC. The sterol band was then injected into an SPB-5 (30 m x 0.25 mm I.D., 0.25 microM film thickness) and the ratio [% campesterol x (% 7-stigmastenol)2]/(% 7-avenasterol) was calculated. The method was tested on extra virgin olive oil; good sterol recoveries and repeatability were obtained. The results were compared with another method. which has a different sample preparation sequence (silica column chromatography, hot saponification and silica TLC). Similar results were achieved with both methods; however, the SPE-cold saponification-TLC-capillary GC was faster, required less solvent and prevented sterol decomposition. The SPE-method was applied to an admixture with 10% of hazelnut oil and to a screening of 11 oils (husk oil, virgin and refined olive oils) from different Mediterranean countries.     

Characterization of the alcoholic fraction of vegetable oils by derivatization with diphenic anhydride followed by high-performance liquid chromatography with spectrophotometric and mass spectrometric detection

Aliphatic and triterpene alcohols present in vegetable oils have been identified and determined by HPLC using UV–vis and MS detection after previous derivatization with diphenic anhydride. The alcoholic fraction was obtained by saponification, extraction and TLC (according to the European Union official procedure). Derivatization was performed in tetrahydrofuran in the presence of suspended grinded urea, which increases the reaction rate and yield. Derivatized extracts were chromatographed on a C8 column using gradient elution with acetonitrile/water mixtures containing 0.1% acetic acid, with UV–vis followed by negative-ion mode MS detection. Using linear discriminant analysis of the HPLC-MS data (extracted ion chromatograms), oil samples belonging to seven botanical origins (hazelnut, sunflower, corn, extra virgin olive, soybean, peanut and grapeseed) were correctly classified with excellent resolution among all the categories.     

Determination of aliphatic alcohols, squalene, alpha-tocopherol and sterols in olive oils: direct method involving gas chromatography of the unsaponifiable fraction following silylation

In general, analyses for aliphatic alcohols, sterols and tocopherols in vegetable oils are performed separately. A simple and reliable procedure is presented for the quantification of the alkanols, squalene, alpha-tocopherol and sterols in olive oils by a direct method involving gas chromatographic (GC) analysis of the unsaponifiable fraction after silylation. The method eliminates the need for a preliminary thin-layer chromatographic (TLC) fractionation prior to GC. External standard calibration with reference substances was used for the quantification of squalene, alpha-tocopherol and sterols and internal standard calibration for the quantification of aliphatic alcohols. The analyte recovery and the repeatability of the quantitative results were evaluated and were acceptable for routine use.     

Thermogravimetric investigations on the thermal degradation of bixin,derived from the seeds of annatto (<Emphasis Type=”Italic”>Bixa orellana L.</Emphasis>)

Conventional methods have been proposed to determine thermal properties of edible vegetable oils. The evaluation of the applicability of DSC and microwave oven (MO) methods to determine the specific heat capacities of the edible vegetable oils was performed. It was observed that the specific heat capacities of each edible oil increased as a function of the saturation of the fatty acids.     

常压火焰离子化质谱技术对食用植物油快速分析的初探

建立了常压火焰离子化质谱(Ambient flame ionization mass spectrometry,AFI-MS)快速分析食用植物油(橄榄油、芝麻油、花生油和葵花籽油)的方法。AFI-MS检出食用植物油(橄榄油、芝麻油、花生油和葵花籽油)中的26种甘油三酯和11种甘油二脂。AFI-MS分析显示,不同的食用植物油(橄榄油、芝麻油、花生油和葵花籽油)得到的质谱图轮廓信息不同。通过对不同食用植物油的甘油三酯相对峰强度进行分析,可初步归纳出食用植物油的类型。AFI-MS分析食用植物油的操作简单,普通的打火机就可以作为离子源用于食用植物油的分析。这种便捷的离子化技术可以用于食用植物油的快速分析。     

A Review of Potential Use of Amazonian Oils in the Synthesis of Organogels for Cosmetic Application

New strategies for the delivery of bioactives in the deeper layers of the skin have been studied in recent years, using mainly natural ingredients. Among the strategies are organogels as a promising tool to load bioactives with different physicochemical characteristics, using vegetable oils. Studies have shown satisfactory skin permeation, good physicochemical stability mainly due to its three-dimensional structure, and controlled release using vegetable oils and low-molecular-weight organogelators. Within the universe of natural ingredients, vegetable oils, especially those from the Amazon, have a series of benefits and characteristics that make them unique compared to conventional oils. Several studies have shown that the use of Amazonian oils brings a series of benefits to the skin, among which are an emollient, moisturizing, and nourishing effect. This work shows a compilation of the main Amazonian oils and their nutraceutical and physicochemical characteristics together with the minority polar components, related to health benefits, and their possible effects on the synthesis of organogels for cosmetic purposes.     

Comparative study of the oxidative and thermal stability of vegetable oils to be used as lubricant bases

Demand for lubricating oils is increasing in the growing Brazilian economy. The use of vegetable bases in exchange of minerals can bring socio-economic and environmental benefits for Brazil. The purpose of this study is to compare the thermal and oxidative stability of vegetable oils related to the bases commonly used as lubricants. In this study, thermogravimetric analysis of castor oil, cotton oil, macauba’s almond oil, passion oil, paraffinic mineral oil, naphthenic oil (NH-140) and synthetic oil (Etro) was performed in inert and oxidative atmosphere to study the thermal and oxidative degradation of the vegetable oils related to the most common lubricants’ oils base. These oils’ oxidation stability were determined by standard procedures (ISO 6886). The use of mineral oil’s additives in these vegetable oils was tested to verify the viability of these additives to improve the oxidative stability of the vegetable oils. The castor oil and the cotton oil presented results of thermal analysis similar to the mineral and synthetic bases values. The castor oil was the only vegetable oil that showed a great oxidative stability. All other vegetable oils had their oxidative stability significantly increased by the additives.     

Monitoring and characterization of ink vehicle autoxidation by inverse gas chromatography

It is now well-established that increased usage of vegetable oils in offset ink formulas aggravates the deinking problems in recycling plants during summer months. The seasonal loss of brightness of recycled paper has been ascribed to increased bonding of oxidatively aged prints to the paper surface. The progress of the oxidative aging of soya bean and linseed oils was followed by inverse gas chromatography. We first report here the rate and extent of vegetable oil oxidation, by measuring the changes in Kovats retention index as a function of the oxidation time. We then characterized the physicochemical changes accompanying the oxidation of vegetable oils from measurements of the partial heat of mixing in the infinite dilution regime.     

Determination of tocopherols and sterols in vegetable oils by solid-phase extraction and subsequent capillary gas chromatographic analysis.

In general, analyses of tocopherols and sterols are performed separately in vegetable oils. By applying solid-phase extraction (SPE) prior to capillary gas chromatography, a simple and reliable procedure for the quantification of both tocopherols and sterols in a single analytical run has been developed. SPE was used as sample clean up procedure for the separation of these minor components from the triacylglycerol matrix, replacing time consuming saponification or on-line LC-GC. The analysis of tocopherols and free sterols in five different vegetable oils illustrates robustness and reliability of this method outlined. Quantification of the analytes was performed by external calibration with reference substances and internal standardization. The recovery of the procedure as well as the repeatability of the quantitative results have been evaluated.