Glass transition and water effects on sucrose inversion in noncrystalline carbohydrate food systems

The effects of water and glass transition on the hydrolysis of sucrose by i nvertase in noncrystalline carbohydrate systems were investigated. Maltodex trin/sucrose (2:1) and maltodextrin/lactose/sucrose (1:1:1) were dissolved in distilled water. Invertase (10 mg/17.2 g) was added. Amorphous samples w ere produced by freeze-drying the solutions. Sorption isotherms were determ ined gravimetrically at 24 degreesC over the 0.113-0.763 a(w), and over 0.2 39-0.764 a(w), the glass transition, T-g was determined using differential scanning calorimetry (DSC). DSC and water sorption results suggested that s amples remained noncrystalline. Sucrose inversion was analysed by monitorin g glucose content during storage. Sucrose hydrolysis occurred at significan t rates at 0.662 and 0.764 a(w). The rate increase was not related to the a pparent glass transition of the systems. (C) 2001 Elsevier Science Ltd. All rights reserved.