High Pressure Processing of Corn and Wheat Starch
Creators:King, Alexander J.
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Publisher:The Ohio State University
Series/Report no.:The Ohio State University. Department of Food, Agricultural, and Environmental Engineering Honors Theses;2005
High hydrostatic pressure (HHP) has been investigated for food preservation as an alternative to thermal processing. HHP has been known to affect high molecular weight polymers causing phase change. Starch has been gelatinized on the order of 600-700MPa, at 25C. Gelatinized starch recrystallizes during storage affecting the texture and shelf life of food products. HHP was applied to corn and wheat starch to study the effects of storage temperature and time on recrystallization of starch in HHP induced starch gels and on the stability of aqueous suspensions of starch. The effect of storage temperature on re-crystallization kinetics of gelatinized corn and wheat starch were evaluated using a differential scanning calorimeter. The textural properties of gelatinized corn and wheat starches during storage were monitored as a function of time using a rheometer. The rate of retrogradation depended on the storage temperatures (23C and 4C) and the botanical origin of starch. The corn and wheat starch stored at 23C exhibited characteristics of strong gels for a longer period of time than that of the starches stored at 4C. Pregelatinizing starch is a method used to modify native starch in order to improve several characteristics including increased solubility. Currently pregelatinized starches are prepared by thermal processing. Thermal and HHP processed pregelatinized corn and wheat starch were compared to native corn and wheat starch to determine the settling characteristics of the starches. The settling characteristics were determined by measuring the turbidity of the corn and wheat starch as a function of time with a spectrophotometer, and by measuring the amount of solid separation and suspension after 24 hours of settling. The data collected show that HHP and thermal processing have advantageous effects for industrial use compared to native corn and wheat starch. The results also show that the settling characteristics depend on the processing conditions and biological origin of the starch.
United States Division of Agriculture, Engineering Honors Department
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