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Spectroscopy in Food Science

Modern spectroscopic methods are becoming increasingly important for probing food as a complex, heterogeneous systems, at the research and development level and for ensuring the quality of raw materials and productsat the place of processing or production. Many methods have recently become simplified to the point where they can be used routinely, especially for consumer protection and legal enforcement. The application of Nuclear Magnetic Resonance (NMR) spectroscopy in food science and food technology increases every day since NMR showed to be fast, precise and extremely sensitive analytical method. In food industry NMR enables composition determination, authentification, testing of food processing and quality control, without destruction of samples and in all states of aggregation. Most foods are highly labile systems, subject to physical, biochemical and chemical changes. These changes can be readily monitored by NMR spectroscopy. In addition, modelling of NMR spectral parameters, which reflect processes in food samples, can be efficiently performed by theoretical quantum chemical calculations. Understanding of relationships among composition, structure and function is important in developing and production of foods for increasing their quality, stability as well as resistance to biological and oxidative degradation. It is known that successive thermic treatments give rise to protein structure changing, i.e. hidrolysis of peptide bonds, alteration of amine end-side-chains and formation of covalent isopeptide bonds. As a consequence, the solubility of food samples decreases. One approach to follow these changes and get deeper insight in their nature is spectroscopic analysis (NMR, IR) of the samples before and after the proccess of extrusion.Wide-line, pulse NMR spectroscopy can be used for this. The first technique enables determination of solid to liquid ratio and content of moisture/water and fat in samples, while the second one may give precise and detailed information on chemical structure and its changes. The analysis of NMR spectral parameters: chemical shifts, coupling constants and relaxation times give qualitative and quantitative data on composition as well as details of structure (types of chemical groups and bonds, their spatial arrangement and orientation, flexibility etc.) of compounds present in food samples. Infrared (IR) spectra may give valuable complementary information to NMR, concerning chemical/functional groups, types of bonds, isotopes, etc. Modern methods of molecular modelling based on ab initio and semiempirical quantum mechanical calculations help in interpreting of spectroscopic results and enable obtaining the details of structural changing during the food processing.

food science; NMR spectroscopy

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