Impairment of the glycolytic system and actin in baker’s yeast during frozen storage

After frozen storage for 7d, the viability and CO₂productivity of a conventional baker’s yeast strain D greatly decreased. The viability of a freeze-tolerant strain, DFT, used for the frozen dough method slightly decreased after the same storage period, while the CO₂productivity greatly decreased. The CO₂productivity and DNase I inhibitory activity of actin of the cell-free extracts prepared immediately after thawing from 7-d frozen-stored cells markedly decreased in both strains. In DFT, however, the productivity and the inhibitory activity of the cell-free extract increased when the extract was prepared after incubation of the frozen-thawed cells at 30°C. The increase in the inhibitory activity first occurred and then the increase in the CO₂productivity. Gel filtration patterns of actin and glycolytic enzymes were compared between cell-free extracts of both strains. Peaks of actin and activity peaks of hexokinase and pyruvate kinase decreased in the strain D after frozen storage, but only slightly in the strain DFT. After frozen storage, phosphofructokinase activity peak shifted to a lower molecular weight in strain D.