Hydroxypropylated maize starch cross-linked with sodium trimetaphosphate
Abstract
Various applications exist for modified starches. The objective of this study was to assess a unique combination of chemical substitutions to maize starch and evaluate the physical properties thereof. Normal maize starch was hydroxypropylated by reaction with propylene oxide (8% based on the weight of the starch (bos)) at 45°C and pH 11.50 in the presence of either sodium sulfate (16% bos) or sodium chloride (16% bos). The hydroxypropylated maize starch was subsequently cross-linked using sodium trimetaphosphate (STMP) at three different levels (0.03%, 0.05% and 0.07% bos). This cross-linking reaction was performed at different temperatures (45°C and 50°C) and at different pH values (11.50 and 11.00) for a total reaction time of 4 hours. Four independent reactions were conducted under each set of experimental parameters. Pasting and paste properties were determined at pH 6.00 for each batch to compare the extent of cross-linking under these different reaction conditions and at pH 3.50 to assess acid stability of the products. Sedimentation volume and paste clarity were also determined to compare other indicators of the degrees of cross-linking under the different reaction conditions. Freeze-thaw stability, gel strength and swelling power and solubility were tested for each batch as well. When breakdown of the neutral pasting curves was evaluated, the most stable granules were produced using the reaction conditions of pH 11.50 and 50°C in the presence of sodium chloride. The same was true when pasting curves at pH 3.50 were evaluated.
Degree
M.S.
Advisors
Hamaker, Purdue University.
Subject Area
Food Science
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