The Thermal Characteristics, Sorption Isotherms and State Diagrams of the Freeze-Dried Pumpkin-Inulin Powders

Powders based on plant raw materials have low storage stability due to their sorption and thermal properties and generate problems during processing. Therefore, there is a need to find carrier agents to improve their storage life as well as methods to evaluate their properties during storage. Water adsorption isotherms and thermal characteristics of the pumpkin powder with various inulin additions were investigated in order to develop state diagrams. Differential scanning calorimetry (DSC) was used to obtained glass transition lines, freezing curves and maximal-freeze-concentration conditions. The glass transition lines were developed using the Gordon-Taylor model. Freezing data were modeled employing the Clausius-Clapeyron equation and its development-Chen model. The glass transition temperature of anhydrous material (Tgs) and characteristic glass transition temperature of maximum-freeze-concentration (Tg ') increased with growing inulin additions. Sorption isotherms of the powders were determined at 25 degrees C by the static-gravimetric method and the experimental data was modeled with four different mathematical models. The Peleg model was the most adequate to describe the sorption data of the pumpkin-inulin powders. Guggenheim-Anderson-de Boer (GAB) monolayer capacity decreased with increasing inulin concentration in the sample.

Automated summary

This study investigated the water adsorption isotherms and thermal characteristics of pumpkin powder with various inulin additions to develop state diagrams. The results showed that the glass transition temperature and characteristic glass transition temperature of maximum-freeze-concentration increased with increasing inulin additions. The Peleg model was the most suitable for describing the sorption data of the pumpkin-inulin powders, and the Guggenheim-Anderson-de Boer (GAB) monolayer capacity decreased with increasing inulin concentration.