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Ageing of Starch Based Systems as Observed with FT‐IR and Solid State NMR Spectroscopy
Author(s) -
Smits Angela L. M.,
Ruhnau Frank C.,
Vliegenthart Johannes F. G.,
van Soest Jeroen J. G.
Publication year - 1998
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/(sici)1521-379x(199812)50:11/12<478::aid-star478>3.0.co;2-p
Subject(s) - retrogradation (starch) , fourier transform infrared spectroscopy , materials science , starch , ageing , glass transition , spectroscopy , proton , moisture , analytical chemistry (journal) , chemistry , composite material , optics , organic chemistry , physics , quantum mechanics , polymer , amylose , biology , genetics
The retrogradation and physical ageing of model starch systems with respect to their glass transition temperatures T g have been investigated by Fourier transform infrared Spectroscopy and solid state NMR spectroscopy. Diffuse reflectance Fourier transform infrared (DRIFT) spectra demonstrate the commencing retrogradation of starch materials stored above their T g by changes in peak lineshapes and intensities in the characteristic area between 995 cm −1 and 1020 cm −1 . Solid state NMR proton relaxation times in the rotating frame (proton T 1ρ ) show a characteristic course in relation to the storage conditions (time, humidity), for which a distinction is made between physical ageing which occurs below the T g , and recrystallisation (retrogradation) which takes place above T g . The proton T 1ρ 's of materials stored below T g increase asymptotically in time due to physical ageing, whereas the proton T 1ρ 's of materials stored above T g increase until a moisture content is reached that rises them above T g , decrease due to further water absorption and then increase due to recrystallisation (retrogradation).