A DSC study of thermal transitions of apple systems at several water contents

The dependence of phase transitions in apple systems at several different w ater contents has been studied by using differential scanning calorimetry ( DSC). The pre-cooled samples with high water fractions show a small but dis tinct thermal effect at low temperature before the final melting of the ice . The samples with low water content show a second order type transition, c haracterised by a temperature which increases with decreasing water content . The temperature/composition behaviour is reported in the form of the so-c alled 'supplemented' state diagram, including the solid/liquid coexistence boundaries and the extrapolated glass transition curve. This diagram contri butes towards understanding the transformations encountered during the temp erature process of partially dried samples of apple. An interpretation is p resented about the existence of phase-segregated regions, which could give the observed thermal effects at low temperatures.