Effects of partial gelatinization on structure and thermal properties of corn starch after spray drying

Partially gelatinized starch was prepared by gelatinizing corn starch at 64–72 °C followed by spray drying (inlet temperature, feed flow rate, air flow rate of 200 °C, 7.2 ml/min and 0.375 m3/h, respectively). The morphology, granule size, crystalline fraction, swelling power and gelatinizing properties of partially gelatinized starch were investigated and compared with those of native starch. The surface morphology of partially gelatinized starch granules was shriveled with multiple surface folds. The granule size of partially gelatinized starch was smaller than that of native corn starch. There was either complete absence of crystalline fraction in partially gelatinized starch or the extent of crystalline fraction was greatly reduced. The swelling power of partially gelatinized starch was higher than that of the native starch below 60 °C, while it was lower than that of native starch above 60 °C. There was an increase in gelatinization temperature and a decrease in gelatinization enthalpy in partially gelatinized starch compared to that of native starch.