(186f) Consecutive Very-High-Gravity Batch Ethanol Fermentations with the Self-Flocculating Yeast SPSC01

Consecutive very-high-gravity batch ethanol fermentation was developed with the self-flocculating yeast SPSC01. Deflocculating of the yeast flocs that resulted in the degeneration of their sedimentation performance was observed with the prolongation of the fermentation system operation, which extended the settling time required for the yeast flocs to separete from the fermentation broth, and exaggerated the toxity of the high level ethanol in the yeast cells, making their viability decreased and the reliability of the fermentation system operation compromised. Experimental results indicated that among the factors affecting the sedimentation performance including the density, concentration and dimension size of the yeast flocs and the apparent viscosity and density of the fermentation broth, the yeast floc size that decreased continuously within the duration of the fermentation and governed by flocculating of the yeast cells dominated the process.