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Using Dielectric Relaxation Spectroscopy to Characterize the Glass Transition Time of Polydextrose
Author(s) -
Buehler Martin G.,
Kindle Michael L.,
Carter Brady P.
Publication year - 2015
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/1750-3841.12887
Subject(s) - polydextrose , glass transition , chemistry , thermodynamics , relaxation (psychology) , materials science , polymer , organic chemistry , psychology , social psychology , physics , food science
Dielectric relaxation spectroscopy was used to characterize the glass transition time, t g , of polydextrose, where the glass transition temperature, T g , and water activity, a w (relative humidity), were held constant during polydextrose relaxation. The t g was determined from a shift in the peak frequency of the imaginary capacitance spectrum with time. It was found that when the peak frequency reaches 30 mHz, polydextrose undergoes glass transition. Glass transition time, t g , is the time for polydextrose to undergo glass transition at a specific T g and a w . Results lead to a modified state diagram, where T g is depressed with increasing a w . This curve forms a boundary: (a) below the boundary, polydextrose does not undergo glass transition and (b) above the boundary, polydextrose rapidly undergoes glass transition. As the boundary curve is specified by a t g value, it can assist in the selection of storage conditions. An important point on the boundary curve is at a w = 0, where T g0 = 115 °C. The methodology can also be used to calculate the stress‐relaxation viscosity of polydextrose as a function of T g and a w , which is important when characterizing the flow properties of polydextrose initially in powder form.