Akademik Veri Yönetim Sistemi
ENZYME AND MICROBIAL TECHNOLOGY, cilt.14, sa.9, ss.762-766, 1992 (SCI-Expanded)
Settling kinetics of champagne yeast were studied with 0.01, 0.05, and 0.10 m NaCl, CaCl2, AlCl3, and 1.00 +/- 0.01 OD660 (optical density at 660 nm) initial yeast concentration at pH 1. In the suspensions with 0.01 M NaCl, the pH of the medium varied between 1 and 3, and the initial yeast concentration changed between 0.74 and 1.25 OD660. Analysis of the data showed that the settling phenomena occurred in two steps: (i) establishment of the diffuse double layer to overcome repulsion, hence achievement of cell-to-cell contact and specific bonding, and (ii) settling of the aggregates. The first stage of the settling phenomenon was described with a zero-order kinetic expression in yeast concentration. The second stage was described with a second-order expression. At pH 1 with 0.01 M concentration of all the salts, repulsion between the yeast cells decreased via reduction in the thickness of the diffuse double layer. Increasing the salt concentration to 0.05 or 0.10 m did not cause substantial change to the settling behavior with NaCl or CaCl2, but flocculation was inhibited because of the surface charge reversal with AlCl3. The first stage of the settling phenomenon was slower at pH 3.0, implying that the isoelectric point of the yeast surfaces was about 3.0.