Spin-spin relaxation time determination of intermediate states in heterogeneous products from free induction decay NMR signals

Botlan, D. J. Le; Ouguerram, Lahcen

doi:10.1016/s0003-2670(97)00274-2

Cited by 31 publications

(21 citation statements)

References 17 publications

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“…It is well known that such phases, with a significant degree of molecular mobility (T 2 ≈ 50-100 µs), can exist, depending on blend composition and thermal history (10,11). Indeed, such species with long relaxation times have been observed and are in the order of approximately 1% for the vegetable fat blends used here (depending on thermal history).…”

Section: Resultsmentioning

confidence: 80%

“…So far, only a few examples are known where the phase behavior of lipids has been assessed (10,11). In recent reports (12,13), it was demonstrated that curve fitting of rapidly sampled transverse NMR relaxation decay curves enabled the quantitative determination of the mesomorphic state of polysaccharides.…”

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confidence: 99%

“…We note that in inhomogeneous magnetic fields, such as those encountered in most commercial low-field TD-NMR spectrometers, one can rarely observe liquid Lorentzian (exponential) decay functions. Commonly, one observes a signal in which the Lorentzian signal is multiplied by Gaussian field inhomogeneity functions (10,11). The field inhomogeneity can be removed, however, by application of a Carr-Purcell-Meiboom-Gill pulse train, thus producing pure Lorentzian decays again (9).…”

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confidence: 99%

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Determination of MG and TG phase composition by time‐domain NMR

Duynhoven

Dubourg

Goudappel

et al. 2002

J Americ Oil Chem Soc

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The feasibility of time-domain NMR curve-fitting methodology for the quantitative determination of TG blend phase compositions was investigated. By studying a range of TG in their different crystal forms, it was shown that the transverse NMR relaxation characteristics of TG differ for the respective crystal polymorphs {α,β,β′}. This enables the TG polymorphism in fat blends to be quantitatively determined by curve fitting. If a liquid phase is present in the blend, curve fitting is able to determine the solid fat content, and the results compare well with those of the accepted NMR methods. The curve-fit method is less hindered by some of the disadvantages of these accepted methods, such as the use of a calibration factor.Paper no. J10095 in JAOCS 79, 383-388 (April 2002).In food technology, the phase composition of fats and oils is an important parameter in process control (1), fat blending properties, and assessments of the quality of various products (2,3). Dilatometry, which is based on the difference in density between the solid and liquid phases, has for a long time been the dominant method to measure the solid fat index (SFI) (4), but this method is laborious and time consuming. Time-domain nuclear magnetic resonance (TD-NMR) has now become the dominant technique, as it offers many advantages regarding speed and ease of operation (2,5,6) and accurate information on the solid-liquid ratio (7,8).The current TD-NMR methods for SFC determination of fat blends have been successfully applied in fat technology for several decades. On one hand, the indirect method (2,7) is considered accurate but not precise, whereas, on the other hand, the "direct" method (2,5) is precise but not accurate and needs a calibration factor (derived from plastic-in-oil samples). In the hands of a skilled operator, the solid-echo (8) method is considered to be both accurate and precise but has never caught on in routine laboratories. Despite its obvious limitation, the direct method has become the most widespread method for SFC determination due to its ease of use and its high precision. However, since the introduction of this direct SFC method in the 1970s, the specifications of commercial TD-NMR equipment have improved dramatically. Also, there is a belief that the current methods do not fully exploit the potential of modern technology.In the detergent area, several applications have been described that show how the phase behavior of surfactants can be assessed by curve fitting of the time-domain data (9). So far, only a few examples are known where the phase behavior of lipids has been assessed (10,11). In recent reports (12,13), it was demonstrated that curve fitting of rapidly sampled transverse NMR relaxation decay curves enabled the quantitative determination of the mesomorphic state of polysaccharides. As the curve-fitting method is not fraught with some of the disadvantages of the current SFC NMR methods, we have embarked on a study to investigate the feasibility of curve fitting for quantification of MG and TG phase compositio...

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Section: Resultsmentioning

confidence: 80%

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confidence: 99%

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Determination of MG and TG phase composition by time‐domain NMR

Duynhoven

Dubourg

Goudappel

et al. 2002

J Americ Oil Chem Soc

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“…The technique could be improved with higher sampling rate of the signal and using the mathematical treatment of the signal as proposed by Le Botlan (1997). For a more reliable interpretation of the results, a precise knowledge of the composition of liquid and solid phases of the tested sample would be required.…”

Section: Resultsmentioning

confidence: 99%

99/02872 Use of pulsed NMR spectroscopy to measure the amount of solid deposits as a function of temperature in waxy crudes

1999

Fuel and Energy Abstracts

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La cristallisation des paraffines dans les pŽtroles bruts et m•me dans les gaz ˆ condensat est un probl•me majeur dans le domaine de lÕexploitation pŽtroli•re. Afin dÕŽvaluer ce risque, on utilise des mod•les thermodynamiques. Ils permettent de calculer la tempŽra-ture de cristallisation commen•ante (TCC) ou Wax Appearance Temperature (WAT) ainsi que la fraction cristallisŽe en fonction de la tempŽrature (pour des tempŽratures infŽrieures ˆ la TCC). Lors de leur dŽveloppement, ces mod•les doivent •tre ŽvaluŽs sur des donnŽes expŽrimentales. Il existe dans la littŽrature et chez les pŽtroliers diffŽrentes mŽthodes pour mesurer la TCC, malheureusement il nÕen est pas de m•me pour la fraction cristallisŽe en fonction de la tempŽ-rature. Dans cet article, nous avons dŽveloppŽ une mŽthode de RMN basse rŽsolution afin de mesurer la fraction cristallisŽe en fonction de la tempŽrature. Elle a dÕabord ŽtŽ ŽvaluŽe sur des mŽlanges de corps purs puis elle a ŽtŽ appliquŽe ˆ des pŽtroles bruts. Les rŽsultats ont ŽtŽ comparŽs ˆ ceux obtenus par analyse calorimŽ-trique diffŽrentielle ainsi quÕaux rŽsultats du mod•le. USE OF PULSED NMR SPECTROSCOPY TO MEASURE THE AMOUNT OF SOLID DEPOSITS AS A FUNCTION OF TEMPERATURE IN WAXY CRUDESParaffin crystallization in crude oils and in gas condensates is a major problem for petroleum exploitation. Thermodynamic models are used to evaluate the risk. With them, one calculates the Wax Appearance Temperature (WAT) as well as the crystallized fraction as a function of temperature, for temperatures below the WAT. During development, these models are tested against experimental data. Although different methods for measuring the WAT are available in the literature and at petroleum companies, such methods unfortunately do not exist for measuring the crystallized fraction as a function of temperature. In this work, we have developed a low resolution NMR method for measuring the crystallized fraction as a function of temperature. The method was first evaluated using pure samples and was then applied to crude oils. The results were compared to those obtained both from differential calorimetry and from the model. La cristalizaci-n de las parafinas en los petr-leos crudos, e incluso en los gases de condensados, constituye un problema agudo en el aspecto de la explotaci-n del petr-leo. Con objeto de evaluar este riesgo, se utilizan modelos termodin ‡micos que permiten calcular la temperatura de cristalizaci-n inicial (TCI) o Wax Appearance Temperature (WAT), as' como la fracci-n cristalizada en funci-n de la temperatura (para temperaturas inferiores a la TCI). Al proceder a su desarrollo, estos modelos se habr ‡n de evaluar acorde a datos experimentales. En la literatura tŽcnica profesional y tambiŽn por parte de las empresas petroleras existen diversos mŽtodos para la medici-n de la TCI, pero, desdichadamente, no ocurre lo mismo al tratarse de la fracci-n cristalizada, en funci-n de la temperatura. Al proceder a este trabajo, hemos desarrollado un mŽtodo de RMN de baja resoluci-n con objeto de medir la...

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“…Even thermal denaturation of proteins (13) was investigated. This type of analysis also can be applied to complex food products (8,9,14,15). In our implementation for lipid-based products, we denoted this approach as transverse relaxation decay deconvolution (TRDD) (8,9).…”

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Practical implications of the phase‐compositional assessment of lipid‐based food products by time‐domain NMR

Duval

Duynhoven

Bot

2006

J Americ Oil Chem Soc

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The objective of this work is to determine the solid fat content (SFC) of the fat-oil phase in oil-in-water (O/W) emulsions, i.e., the droplet SFC, using transverse relaxation decay deconvolution (TRDD) analysis. The TRDD NMR experiment classifies protein protons as mobile, semimobile, and nonmobile. Hence, protein contributes more or less to the solid content detected by TRDD as a function of pH, protein content, and protein denaturation. By taking into account the protein contribution to the overall solid content, one can estimate the droplet solid content in O/W emulsions. The SFC can then be deduced if one converts the ingredients' mass fraction into ingredients' proton fraction using the ingredients' proton densities.Paper no. J11392 in JAOCS 83, 905-912 (November 2006). KEY WORDS:O/W emulsions, SFC, solid content, transverse relaxation decay deconvolution (TRDD), whey proteins.The key to understanding many functional properties of food products and materials is in the physical state of their ingredients (1). Texture (hardness) and melting behavior of margarine and chocolate, for example, are determined by the phase behavior of their lipid component, i.e., the balance between the solid/liquid state and the effects of crystal polymorphism (1,2). For many cereal materials, the phase composition of the carbohydrate components determines processing and textural properties. The various phases comprise different crystalline starch polymorphs, gel states, mesomorphic phases, and liquid-like dissolved phases (3,4). For the assessment of crystal polymorphism of food materials, one traditionally deploys X-ray diffraction and thermal analysis (mostly DSC) (5). These techniques are unsurpassed in addressing specific phase-compositional details of lipid and carbohydrate materials, such as polymorph identification. However, they mostly fall short when the phase composition of complex foods products needs to be assessed in a quantitative manner. For this purpose, NMR relaxometry currently presents the most powerful option. Strong advantages of NMR over other methods are that it probes molecular mobility of the different phases, and that the obtained signals directly relate to corresponding proton densities. For this purpose, dedicated low-field NMR relaxometers have been designed that are relatively cheap and easily operated by nonexperts. The earliest example of a widespread application within the foods community is the determination of solid fat content (SFC) of lipids by NMR (6). This methodology uses rather crude acquisition and data treatments of the free induction decay (FID). More recent sophisticated NMR line-shape analysis procedures (7-9) were introduced to derive detailed quantitative phase-compositional information on polysaccharides (10,11) and on lipids (12). Even thermal denaturation of proteins (13) was investigated. This type of analysis also can be applied to complex food products (8,9,14,15). In our implementation for lipid-based products, we denoted this approach as transverse relaxation decay deconvolu...

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Spin-spin relaxation time determination of intermediate states in heterogeneous products from free induction decay NMR signals

Cited by 31 publications

References 17 publications

Determination of MG and TG phase composition by time‐domain NMR

Determination of MG and TG phase composition by time‐domain NMR

99/02872 Use of pulsed NMR spectroscopy to measure the amount of solid deposits as a function of temperature in waxy crudes

Practical implications of the phase‐compositional assessment of lipid‐based food products by time‐domain NMR

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