Physicochemical properties of pregelatinized wheat and corn starches in the presence of different concentrations of L-ascorbic acid

Pregelatinized starches are commonly used in many foods, particularly those processed at low temperature, to enhance viscosity and provide a desirable texture. The functional properties of the pregelatinized starch can be affected by other components used in food systems. The main purpose of this study was to determine the effects of various levels of L-ascorbic acid (L-AA) including 0, 100, 500, and 1000 mg/kg (starch basis) on some functional properties of pregelatinized wheat (PGW) and corn (PGC) starches. The pH of the samples was reduced significantly as the level of L-AA increased. Cold-water solubility increased while water absorption decreased with increasing concentrations of L-AA and exposure time. Cold water viscosity as determined by a Rapid Visco Analyser decreased as the amount of L-AA increased. Addition of LAA reduced gel firmness, increased turbidity during storage for 72 h and enhanced syneresis during five freeze-thaw cycles. The general behaviors of PGWand PGC starches in the presence of different levels of L-AA were similar. However, PGW starch showed higher cold-water viscosity, harder gel texture, more turbidity, and greater syneresis than the PGC starch.