Estimation of crystalline phase present in the glucose crystal–solution mixture by water activity measurement

Abstract

The amount of crystalline fraction present in monohydrate glucose crystal–solution mixture up to 110% crystal in relation to solution (crystal:solution=110:100) was determined by water activity measurement. It was found that the water activity had a strong linear correlation ( R 2=0.994) with the amount of glucose present above saturation. Difference in the water activities of the crystal–solution mixture ( a w1) and the supersaturated solution ( a w2) by re-dissolving the crystalline fraction allowed calculation of the amount of crystalline phase present (Δ G) in the mixture by an equation Δ G=846.97( a w1− a w2). Other methods such as Raoult's, Norrish and Money–Born equations were also tested for the prediction of water activity of supersaturated glucose solution.