The thermal behavior associated with the melting of ice was investigated by differential scanning calorimetry (DSC) for the
gel and L-subgel phases of dipalmitoylphosphatidylcholine (DPPC)-water system of varying water contents up to a full hydration. By
calorimetric analysis previously developed by us, the numbers of differently bound water molecules were estimated, and used
to construct water distribution diagrams (i.e., a plot of the cumulative numbers of these water molecules vs. water content)
for the two phases. A comparison of the diagrams revealed the critical role of interlamellar water which changes from freezable
to non-freezable one in a conversion of the gel to the L-subgel phase by the thermal annealing.