Chloramine T with iodine: A new reagent to determine the iodine value fo edible oils

Chloramine T (N-chloro-p-toluenesulfonamide sodium salt) and iodine (2:1, w/w) in carbon tetrachloride and acetic acid (1:1, vol/vol), referred to as reagent (I) was found to be effective for the determination of Iodine value of edible oils. Reagent (I) reacted quantitatively with the double bonds of oils of known weight. The reagent left unreacted after 20–25 min was titrated against standard sodium thiosulfate solution (0.04 M) in presence of potassium iodide (10%, 5 mL). The difference in volume of sodium thiosulfate solution consumed by reagent (I) without and with oil was a basis to calculate the iodine value of oils used. The iodine values of different oils were also determined separately following the standard procedure of Wijs, and calculated iodine value was obtained from the gas chromatographic profile of fatty acids. The iodine value obtained by the new method was in agreement with the results of the standard methods. The results obtained indicate that the method could be a complementary or an alternative to the Wijs method.     

Stabilisation of edible oils with natural antioxidants

Natural antioxidants have recently gained increased interest because of the belief that natural food ingredients are better and safer than synthetic ones. The review presents the results on stabilisation of the main edible oils with different types of natural antioxidants. Sources of natural antioxidants are spices, herbs, teas, oils, seeds, cereals, cocoa shell, grains, fruits, vegetables, enzymes, proteins. Researchers concentrate on ascorbic acid, tocopherols and carotenoids as well as on plant extracts containing various individual antioxidants such as flavonoids (quercetin, kaemferol, myricetin), catechins or phenols (carnosol, rosmanol, rosamaridiphenol) and phenolic acids (carnosic acid, rosmarinic acid). Ascorbyl palmitate is regarded as a 'natural' antioxidant because it is hydrolysed in the body to ascorbic and palmitic acids. Among the herbs of the Lamiaceae family, rosemary has been more extensively studied and its extracts are the first marketed natural antioxidants. Oregano, which belongs to the same family, has gained the interest of many research groups as a potent antioxidant in lipid systems. The review concerns the following main topics: stabilisation of oil with individual natural antioxidants, interaction of antioxidants with synergists, stabilisation of oil with extracts or dry materials from different plant sources (e.g. herbs and spices), stabilisation at frying temperatures and in emulsions.     

Calculation of iodine value from measurements of fatty acid methyl esters of some oils: Comparison with the relevant American Oil Chemists Society method

A new calculation method for the determination of iodine value (IV) from measurements of fatty acid methyl esters is proposed. The method is based on the quantitative determination of fatty acid methyl esters of vegetable oils by capillary gas chromatography. IV is a measure of the number of double bonds in the unsaturated fatty acids in one gram of oil. The analytical methodology of its evaluation includes the use of rather health dangerous reagents, and for that reason is mostly avoided by laboratory analysts. A calculation procedure to determine the IV of oils from their fatty acid methyl ester composition is in use based on the American Oil Chemists’ Society (AOCS) method Cd 1c-85. A new calculation procedure for IV, based also on the evaluation of the fatty acid methyl esters of oils, was developed. The application of the proposed calculation methodology was checked with olive oil, corn oil, soybean oil, cottonseed oil, and sunflower seed oil. The proposed calculation gave results in better agreement with the Wijs method than with the relevant AOCS method.     

Analysis of the induction period of oxidation of edible oils by differential scanning calorimetry

Oxidation of rapeseed and sunflower oils has been studied by differential scanning calorimetry under non-isothermal conditions and by Oxidograph under isothermal conditions for various temperatures. The parameters of an Arrhenius-like equation describing the temperature dependence of induction period have been obtained. A new method for evaluation of the parameters from nonisothermal diffential scanning calorimetry measurements, based on the dependence of onset temperature of the oxidation peak on heating rate, is presented. It has been shown that the method gives parameters not affected by systematic errors. These can be used in modeling the oxidation process where the effects of oxygen diffusion, heat transfer, and evolution of reaction heat are explicity involved. The results obtained by differential scanning calorimetry are compared with the Oxidograph measurements. The discrepancies between the results obtained by the two methods are accounted for by oxygen diffusion within the samples.     

Discrimination of edible oil products and quantitative determination of their iodine value by Fourier transform near-infrared spectroscopy

This work demonstrates the application of partial least squares (PLS) analysis as a discriminant as well as a quantitative tool in the analysis of edible fats and oils by Fourier transform near-infrared (FT-NIR) spectroscopy. Edible fats and oils provided by a processor were used to calibrate a FT-NIR spectrometer to discriminate between four oil formulations and to determine iodine value (IV). Samples were premelted and analyzed in gass vials maintained at 75°C to ensure that the samples remained liquid. PLS calibrations for the prediction of IV were derived for each oil type by using a subset of the samples provided as the PLS training set. For each oil formulation (type), discrimination criteria were established based on the IV range, spectral residual, and PLS factor scores output from the PLS calibration model. It was found that all four oil types could be clearly differentiated from each other, and all the validation samples, including a set of blind validation samples provided by the processor, were correctly classified. The PLS-predicted IV for the validation samples were in good agreement with the gas chromatography IV values provided by the processor. Comparable predictive accuracy was obtained from a calibration derived by combining samples of all four oil types in the training set as well as a global IV calibration supplied by the instrument manufacturer. The results of this study demonstrate that by combining the rapid and convenient analytical capabilties of FT-NIR spectroscopy with the discriminant and predictive power of PLS, one can both identify oil type, as well as predict IV with a high degree of confidence. These combined capabilities provide processors with better control over their process.     

Rapid and direct lodine value and saponification number determination of fats and oils by attenuated total reflectance/fourier transform infrared spectroscopy

A simple, rapid and reproducible method of determining the iodine value (IV) and saponification number (SN) for fats and oils was developed with an attenuated total reflectance/Fourier transform infrared spectrometer and commercially available triglycerides as calibration standards. Partial least squares was used to determine the spectral regions correlating with the known chemical IV and SN values, and the calibration set was augmented with additional standards generated by spectral co-adding techniques. The calibration model obtained was used to analyze commercially available fats and oils with a wide range of IV and SN values, and the results were compared to the values obtained by American Oil Chemists’ Society methods. With the spectrometer calibrated and programmed, IV and SN results could be obtained within 2–3 min per sample, a major improvement over conventional wet chemical methods.     

Rapid determination of cis and trans content, iodine value, and saponification number of edible oils by fourier transform near-infrared spectroscopy

Fourier transform near-infrared (FT-NIR) spectroscopy was evaluated as a means of simultaneously determining the cis and trans content, iodine value (IV), and saponification number of neat fats and oils. Reference values for these parameters were obtained from oils using a previously developed mid-FTIR Edible Oil Analysis Package. Two partial least squares calibrations were developed for a 5-mm heated flow cell, the first a process calibration based on hydrogenated soybean samples and the second a more generalized calibration based on an oil samplematrix containing many oil types and designed to remove any correlations among the parameters measured. Each calibration performed well with its own validation samples; however, only the noncorrelated calibration was able to analyze oil samples accurately from a variety of sources. It was found that NIR analysis maintained the internal consistency between cis/trans and IV, and the accuracy and reproducibility of the predictions were on the order of ±1.5 and ±1.0 units, respectively, for all parameters evaluated. FT-NIR is shown to be a very workable means of determining cis/trans/IV values and saponification number for edible fats and oils, and it provides a rapid alternative to the commonly used chemical and physical methods presently employed in the industry.     

A comparison of mid-infrared and raman spectroscopies for the authentication of edible oils

Robust, routine, and rapid instrumental methods for the determination of the authenticity of edible oils, and the detection of adulteration, are continually being sought. In this paper, we compare mid-infrared and Raman spectroscopies for their ability to discriminate between oils of differing botanical origin and for their ability to detect added adulterants. Furthermore, we used sufficient numbers of samples to permit a comparison of some of the chemometric methods (linear discriminant analysis, artificial neural networks) available and looked at the results obtained when the two spectroscopic datasets were combined. We show that mid-infrared spectroscopy, in combination with linear discriminant analysis, gave the best classification rates and adulteration detection levels compared to Raman or combined data.     

Determination of iodine value with a fourier transform-near infrared based global calibration using disposable vials: An international collaborative study

A method for the determination of iodine value (IV) by Fourier transform-near infrared (FT-NIR) spectroscopy was developed and evaluated in an international collaborative study. The FT-NIR analyzer employed in this work uses disposable vials for sample handling and incorporates validation protocols designed to ensure that the calibration will give accurate results from analyzer to analyzer and stability over time without any further calibration development work. The global IV calibration was developed from over 1,200 animal, marine, and vegetable oils and fats, which were obtained on a number of different instruments worldwide. The Standard Error of Cross Validation measured from a range of 0–190 IV varied from ±0.2–1.4 IV (1 sigma). The repeatability for all models was on the order of 0.1 IV, which states that most of the error was inherited from the primary methods. Finally, an international interlaboratory study was carried out with 16 samples obtained from the AOCS Smalley Laboratory Proficiency Program and an oil processor. The average reproducibility error in any one lab was better than 0.15, and the average reproducibility between labs was better than 0.33. An uncertainty of 0.45 was calculated from the average FT-NIR values obtained from the collaborative study vs. the AOCS Certified Wijs method (Cd 1d-92).     

Characterization of edible oils and lard by fourier transform infrared spectroscopy. Relationships between composition and frequency of concrete bands in the fingerprint region

Fourteen samples of edible oils and lard have been studied by means of Fourier transform infrared spectroscopy. The spectra were recorded from a film of pure oil or lard between two discs of KBr. The bands of the spectra were assigned to different functional group vibrations. The frequencies of some bands have constant values, independent of the nature of the sample. However, frequencies of other bands, some of them in the fingerprint region, depend greatly on the sample composition. Equations obtained from frequency of these bands and composition data are valuable to predict the proportions of saturated, monounsaturated and polyunsaturated acyl groups in oils and lard.     

一种测量石蜡相变乳液过冷度的新方法：平衡态比容法

石蜡相变乳液是集储热与传热于一体的新型功能流体,具有广阔的应用前景。但石蜡相变乳液在降温时会出现过冷现象,极大降低了其储热与传热的性能。采用差示扫描量热法（DSC）测量石蜡相变乳液的过冷度受到升/降温速率的影响,且升/降温速率越大,测得过冷度越大。提出一种测量石蜡相变乳液过冷度的方法——平衡态比容法。该方法通过测量石蜡相变乳液在不同温度下的比容,以确定乳液中石蜡粒子在升/降温过程中的相变温度,并进一步求解石蜡相变乳液的过冷度。实验结果表明,本研究提出的平衡态比容法能准确测量石蜡相变乳液的过冷度,并从比容变化的角度揭示石蜡相变乳液过冷现象的机理。     

A new quantitative criterion to determine slag corrosion resistance of refractories for incinerators

Selecting the most suitable refractory lining from various types/grades of products provided by different suppliers for the hazardous waste incineration rotary kiln is not an easy job to reach a 23-month lifetime. Real-life industrial scale test is time-consuming, i.e., only one or two new products can be tested each year or every other year. Crucible test is a fast way to give a first assessment to test the adaptability of a given product to a slag. However, the classic visual observation to determine the slag penetration zone is usually inconclusive when the materials of the same group are tested and can be sometimes misleading. In this study, crucible tests were performed for 10 commercial chromia-corundum bricks from various sources. After examined with detailed analysis with SEM (Scanning Electron Microscopy) and EDS (Energy Dispersive X-Ray Spectroscopy), highly precise quantitative values of corrosion zones width for samples are derived. A non-dimensional number, the Wear ratio, is introduced as a quantitative criterion to characterize the refractory corrosion resistance. By using this Wear ratio, a correlation is found with the chromia concentration. Quantitative results obtained by this criterion are in line with the real-life observations of industrial scale tests.     

A study of the oxidation and wear properties of vegetable oils: Soybean oil without additives

The use of biodegradable lubricants in diverse applications continues to increase. Vegetable oils (e.g., soybean oil) are the main biodegradable lubricant base stocks used world-wide. However, there are concerns about their oxidative stability and low-temperature performance. Improvements in oxidative stability can be made through chemical or genetic modifications. This work compared the effects of oils with different chemical compositions. Soybean oil, high-oleic soybean oil, and epoxidized soybean oil were compared in laboratory bench tests. The tests conducted include the Penn State sequential four-ball wear test and the Penn State micro-oxidation test. Oxidation products from the micro-oxidation test were analyzed by FTIR and gel permeation chromatography. In this paper, all oils were evaluated neat, without additives.     

A density based segmentation method to determine the coordination number of a particulate system

The coordination number is an important parameter for understanding the particulate systems, especially when agglomerated particles are present. However, experimental determination of the coordination number is not trivial. In this study, we describe a 3D classification method, which is based on the revised DBSCAN (Density-Based Spatial Clustering of Applications with Noise) and its application to X-ray micro-tomographic (XMT) images to determine the coordination number distribution. Pellets of micro-crystalline cellulose were used as model particles. The validity of the segmentation was checked by comparing the particle size distribution (PSD) obtained by XMT-DBSCAN with PSD obtained by optical microscopy. The results were found to be in good agreement, demonstrating the suitability of the DBSCAN method. The means and standard deviations of coordination numbers were (8.2±1.7, n=994 particles), (8.1±1.5, n=904) and (6.2±1.2, n=159) for pellets with length based mean sizes of 157, 307 and 437 μm, respectively. The coordination number distribution was in line with previous finding in mono-sized acrylic beads.