Mathematical Model for Prediction of Glass Transition Temperature of Fruit Powders

Abstract

Glass transition temperature (Tg) has been identified as a critical factor to predict quality of foodstuffs during processing or storage. Differential Scanning Calorimetry (DSC) was used to determine the Tg of 4 types of berry powders as a function of water content, and equilibrium moisture content was measured over different saturated solutions using the gravimetric method. The Guggenheim-Anderson-deBoer model was used to predict water activity (a w ). Four models were tested for their ability to predict Tg as a function of the solid fraction. The combined effects of Tg and a w were incorporated into a new mathematical expression. The expression requires the determination of Tg (dry solids) of the product and data on equilibrium moisture sorption. The mean percent error of the model predictions is less than 3.6% when compared to experimental data.

Collapse and Color Changes in Grapefruit Juice Powder as Affected by Water Activity, Glass Transition, and Addition of Carbohydrate Polymers

“…Combining the GAB and Gordon and Taylor models, Khalloufi et al 37 proposed a useful equation that relates T g and a w , valid from a w =0, given by:…”

The use of moisture sorption isotherms and glass transition temperature to assess the stability of powdered baby formulas

“…However, a slight increase in moisture content significantly reduces T g . Therefore, moisture sorption isotherms and T g data provide critical values for the water activity and moisture content at room temperature [9,28,29]. Storage of dehydrated foods at humid conditions may increase water activity (a w ) as a result of water sorption, and the glass transition of the materials may decrease to below ambient temperature.…”

Physical Properties of Inulin and Technological Applications

“…As functional agent, inulin has been employed as excipient, additive, thickener, emulsifier, gelling agent, sugar and fat substitute, etc. From the point of view of phase stability, the most common problems presented during the handling of amorphous powders are stickiness, agglomeration, crystallization, loss of volatile compounds, and crush (Andhikari et al 2001;Kay and Nottingham 2008;Khalloufi et al 2000). Recently, the stability of inulin during the storage has been evaluated and related to the concepts of a w and Tg, where a w is expressed as the amount of water adsorbed per 100 g of dried sample.…”