Drying and Crystallization of Sucrose Solutions in Thin Films at Elevated Temperatures

Thin sucrose films were dried over 30‐min periods during which sucrose crystal growth rates were monitored by videomicroscopy. Drying parameters and sucrose solution properties were varied to determine their effect on initial sucrose crystal growth rates. Growth rates increased by a factor of 4.5 as temperature increased from 40 to 70 °C. Varying initial sucrose concentration (70 to 80%) and drying air velocity (2 to 5 m/s) produced no change in crystal growth rates. Increases in film thickness from 150 to 450 μm and the presence of moisture in the drying air reduced growth rates by 33% at 70 °C, but had no effect at 50 °C. The addition of invert sugar (up to 5%) reduced growth rates by a factor of 2 to 3.