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Publisher Summary Nuclear magnetic resonance spectroscopy (NMR) is now a standard analytical technique that has been applied in a number of ways to the study of lipids. This chapter describes the use of low-resolution 1H NMR and of high-resolution 13C NMR spectroscopy. The use of imaging techniques is described elsewhere in this book. High-resolution 1H NMR spectra are of value in determining the structure of individual organic compounds but have found only limited use in the study of fat mixtures. The CH3 signal for n-3 acids differs from that for other unsaturated and for saturated acids; In the period 1955-70 dilatometry was the most widely accepted method for the characterization of fats. The development of a continuous-wave (wide-line) instrument (Newport Analyser) was investigated in detail from 1968 to 1975. It offered certain advantages regarding speed and ease of operation. However, serious drawbacks remained. No efforts were pursued to employ pulsed NMR for solid fat determination until 1973 because of the unavailability of cheap instruments. Bruker was the first to produce commercially a fully automated instrument for this purpose, followed by the Praxis Corporation USA. Pulsed low-resolution NMR is becoming a standard technique for the determination of solid fat content (SFC). Other applications that have found a positive response in the food industry include studies of fat polymorphism, studies of fatty emulsions, determination of oil content of seeds and meals, and determination of humidity in a variety of foodstuffs. |
