Abstract
We use pressure-variable differential scanning calorimetry to detect and characterize thermally induced transitions (glass, melting, gelatinization) in pre- and post-extruded wheat flour. The resulting data allow us to construct a two-dimensional state diagram which maps the physical states that pre- and post-extruded wheat flour can assume, at constant pressure, as a function of moisture content, temperature, and the specific mechanical energy, SME, generated in the extruder. We describe how this state diagram can be used to map the path of extrusion processing, to assess the impact of extrusion conditions, and, ultimately, to design formulations and processing conditions that result in desired end-product attributes. For the extrudates, we find that the extent of processing-induced fragmentation, as monitored by reductions in the extrudate glass transition temperature,T g, increases with the SME generated in the extruder. We demonstrate that a wheat-flour state diagram, which includes the glass curve of the wheat-flour extrudates produced at various SME values, allows one to predict and control the impact of processing conditions on extrudate properties.
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This is publication D 10544-6-95 of the New Jersey Agricultural Experiment Station, supported by State funds and the Center for Advanced Food Technology of the New Jersey Commision on Science and Technology. The authors would like to thank Dr. G. Eric Plum for his comments on the manuscript and Dr. Karwe for producing extrusion samples.
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Kaletunç, G., Breslauer, K.J. Construction of a wheat-flour state diagram. Journal of Thermal Analysis 47, 1267–1288 (1996). https://doi.org/10.1007/BF01992827
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DOI: https://doi.org/10.1007/BF01992827