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Nuclear magnetic resonance (NMR) - Articles and news items
Issue 1 2010, Past issues / 22 February 2010 / Adrian J. Charlton, Food and Environment Research Agency, Department for Environment, Food & Rural Affairs
For many years, NMR spectroscopy was largely overlooked by the food industry. Maybe this was understandable. The instruments were expensive, the skills required to operate them could at best be described as specialist and there wasn’t a broad understanding of the way in which the technology could be applied within the industry. I joined the Food Science Group at Fera (then the Central Science Laboratory) in 1999. NMR spectroscopy was mainly used for measuring isotopes to check the authenticity of wines and fruit juice, whilst an archaic bench top contraption was used for fat and water measurements.
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Issue 2 2009 / 1 June 2009 / Matthieu Adam-Berret and François Mariette, Cemagref & Université européenne de Bretagne
Fats are present in most food products and they have a significant importance for fat-containing products such as chocolate and butter. The physical properties of fats depend on the polymorphic behaviour and inter-solubility of their major triacylglycerol components and the phase behaviour of these mixtures is of paramount importance for the food industry. Indeed, fat structures formed by their crystals determine the functional properties of fat-containing products such as their texture, plasticity and morphology. DSC and XRD are the two techniques generally used to characterise fats. Crystal size is another important parameter for determining the physical properties of fats because it affects the rheological properties and consequently modifies taste, graininess and texture.
The use of low-field NMR spectrometers in the food industry began in the 1970’s with the commercial availability of the first bench-top NMR systems. Several applications were developed during the following years, but they were limited to the determination of water and fat content and measurement of the solid fat index. Surprisingly, the number of applications did not increase much during the following twenty years. In 1992, the first International Conference on Applications of Magnetic Resonance in Food Science was organised and since that time, with the improvements in bench-top NMR characteristics, new applications have been put forward. One of the most well-known is droplet size measurement based on diffusion coefficient measurements. The use of NMR relaxation times was suggested, not only for determining water and fat content but also for investigating food structure. Furthermore, NMR is a non-destructive technique and can be used to perform dynamic measurements, for example with changing temperatures or for studies relating to storage time. (more…)
Issue 3 2008, Past issues / 18 August 2008 / Dr Hanne Christine Bertram. Senior Project Scientist, University of Aarhus
Water is a major constituent in many foods. For example, in several of our basic food items such as muscle-based foods and vegetables, water is the dominating component and is in many ways of primary importance for the quality of these products. Low-field proton NMR relaxometry is an excellent technique for studying water properties in complex systems such as food.
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Issue 2 2008, Past issues / 13 June 2008 / J. P. M. van Duynhoven, Gert-Jan W. Goudappel, Elena Trezza, Adrian M. Haiduc, Franck Duval, Wladyslaw P. Weglarz, Unilever Food and Health Research Institute, Vlaardingen, The Netherlands
NMR is a versatile tool for structural assessment of food materials and this pertains in particular for its benchtop and hand-held implementations. Such “small NMR” equipment can literally be deployed in all phases of foods innovation. This is illustrated by several industry examples.
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Issue 1 2008, Past issues / 28 February 2008 / Dr. Peter Rinke, Sure Global Fair International E.V. and Dr. Manfred Spraul, Bruker-BioSpin GmbH
Important tasks of the fruit juice industry are to protect the good and healthy image for its whole product range and protect the market against any unserious producers. In order to assure fair competition, safe products and consumer satisfaction, the fruit juice industry has installed independent and centralised control bodies under the umbrella of EQCS (European Quality Control System). SGF (SGF INTERNATIONAL E.V. – SURE GLOBAL FAIR) is the biggest member association of and its department, SGF/IRMA (International Raw Material Assurance) and is in charge of controlling the supply market in more than 50 countries worldwide. Facing a very large number of control samples, conventional analyses are limited to spot checks and more or less arbitrary choices of specific aspects to control, due to high costs. Systematic so called “full analyses” are too expensive for any control organisation and for the companies’ own entrance controls. Besides safety controls, the analytical scope should cover the addition of external sugar, water, flavour compounds or cheaper fruit types than the declared ones1,2.
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