The circumstances of freezing in the freeze-drying process of haemoderivatives.

It appears from the experiments of the authors that the macroscopic changes taken place during freezing and heating could be explained by the formation of an eutectic crystalline structure in the case of human plasma and albumin solutions. The temperature interval of eutectic spot formation showed good agreement with the temperature range of initial thawing as determined by the DTA method, i.e. with the working zone freeze-drying. It was possible to determine the maximum temperature of complete solidification from the resistance curves of the haemoderivatives. Judging from the shape of the resistance curves, the phenomenon of undercooling did not emerge with the freezing rate applied. Examining the optimal freezing rate, it appeared on the basis of some quality characteristics of the freeze-dried end-product, that the best results were obtained with --30 degrees C freezing in the case of albumin and plasma, and with --45 degrees C freezing in the case of normal and iv immunoglobulins. But the authors deem it necessary to conduct further experiments in this respect.