Determination of Williams–Landel–Ferry constants for a food polymer system: Effect of water activity and moisture content

The Williams–Landel–Ferry (WLF) equation is a useful tool in the prediction of temperature-induced physical changes in foods that are exposed to specific food processing and storage conditions, because so many deteriorative processes are diffusion controlled. In food polymers, viscoelastic propertie...

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Bibliographic Details
Published in:Journal of rheology (New York : 1978) 2001-07, Vol.45 (4), p.903-912
Main Authors: Yildiz, M. E., Kokini, J. L.
Format: Article
Language:English
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Summary:The Williams–Landel–Ferry (WLF) equation is a useful tool in the prediction of temperature-induced physical changes in foods that are exposed to specific food processing and storage conditions, because so many deteriorative processes are diffusion controlled. In food polymers, viscoelastic properties are a strong function of the key plasticizers present in foods, such as water. However, WLF constants as a function of water content and water activity are not available in the food literature. In this research, we investigated the WLF properties of soy flour as a function of water activity and elucidated the effect of water on the magnitude of WLF constants. Based on a time-temperature superposition principle, shift factors (a T ) were obtained, which were used to estimate WLF constants. WLF constants for soy flour were shown to be material specific and different from the “universal values.”
ISSN:0148-6055
1520-8516
DOI:10.1122/1.1380425