The freezing of Mozzarella cheese by immersion in NaCl solutions may be an innovative procedure for the dairy industry because it combines conveniently salting and freezing processes. The influence of this type of freezing method and of the frozen storage of samples on the microstructure of Mozzarella cheese was studied. Slabs (2 x 10 x 10 cm(3)) were immersed in 23% w/w NaCl solutions (control samples: 4 degrees C, 90 min; frozen samples: -15 degrees C, 180 min). Half of the frozen samples were immediately thawed at 4 degrees C. The other half was stored at -20 degrees C for 2 months and then was thawed at 4 degrees C (frozen-stored samples). Samples were stored at 4 degrees C and assayed at 1, 14 and 41 days. Although the immersion freezing of Mozzarella cheese affects its microstructure, only small differences were observed in the frozen-stored samples compared to control and frozen samples. Those differences consisted on less defined honeycomb appearance and the presence of small cracks at 41 days of ripening in the frozen-stored samples. Therefore, it was considered that the immersion freezing might be useful for the manufacture and commercialization of Mozzarella cheese. (C) 2008 Elsevier Ltd. All rights reserved.