Spray Drying of Fruit Juice with Vegetable Fibre as Carrier

The production of free flowing powder by spray drying of sugar-acid rich foods requires an appropriate carrier. High molecular weight materials such as maltodextrins are commercially used as a drying aid because of their higher glass transition temperature (Tg). Alternatively, fibre-rich by-products from fruit and vegetable juice processing might provide high molecular weight elements that are suitable as a drying support. Freeze dried carrot fibre was centrifugal-milled to 50-100 µm sizes. Fructose and apple juice concentrate were used in this study. The fibre semed to show as crystal induction in the spray drying products of the two materials. Dried sucrose, glucose and fructose were used to study glass transition temperature of melted amorphous sugars and mixtures by the visual experiment and DSC at 0.1°Cmin-1 of heating and cooling scans. The Gordon-Taylor equation and the Coachman and Karaze equation were used to predict Tg of sugar mixtures. Dielectric analysis in the range 200 Hz -1 MHz between 10-105 ° C were applied to find the onset Tg (based on DSC results) from freeze dried mixtures of carrot fibre+fructose.