No protecting medium was used for the freeze-drying of Saccharomyces cerevisiae free cells and those immobilized on gluten pellets to form an immobilized biocatalyst. The use of these for glucose fermentations at various initial glucose concentrations, temperatures and initial pH values showed that the fermentation time for the first batch with freeze-dried immobilized cells was 1.5- to 3-fold less than that with free freeze-dried cells. In the second repeated batch, the fermentation time of freeze-dried immobilized cells was less, in some cases up to three times less than the first batch and reached the fermentation time of fresh immobilized cells. After storage for 16 months at 4 degreesC, freeze-dried immobilized biocatalyst was used for five repeated batch fermentations of glucose. The fermentation time decreased continuously until 18 h, which was less than the half of the fermentation time of the first batch. (C) 2001 Elsevier Science Ltd. All rights reserved.