Effect of polymer addition on the physical properties of freeze-dried soup solid.

The effect of polymers (gelatin, starch, and maltodextrin) on the physical properties of freeze-dried model soup (sodium chloride, sucrose, and monosodium glutamate) was investigated. The polymers were added to the soup solution at 1 or 3% (w/v), which was then freeze-dried at 25 or 50 °C. Gelatin and maltodextrin prevented crystallization of sodium chloride to a greater extent than starch under freezing. Freeze-drying was conducted above the freeze-concentrated glass transition temperature. Polymer addition prolonged drying time, but prevented structural deformation. Gelatin enhanced the physical strength of the freeze-dried solid more than starch and maltodextrin because of its gel-network. In a dissolution test, 1% gelatin, and 1 and 3% maltodextrin exhibited greater dissolution than the other samples. The drying rate was lower at 50 °C, with minor modifications to the other properties. From these results, it was concluded that 1% gelatin was useful as a physical stabilizer for freeze-dried soup. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13197-021-05161-x. © Association of Food Scientists & Technologists (India) 2021.