Dialysis and ultrafiltration of molasses for fermentation enhancement

The pore structure of a commercially available dialysis membrane was modifi ed by the deposition of crystals of calcium octanoate in the membrane matri x. The modified structure resulted in a significant reduction in sucrose lo ss when dialysis was used to reduce the potassium concentration of a soluti on of sucrose and potassium chloride. The results of fermentation studies o f artificial molasses substrates using a proprietary strain of Saccharomyce s cerevisiae showed that the optimum potassium concentration for micro-orga nism activity was similar to 10.5 g l(-1). Subsequent fermentation studies on an authentic Australian molasses substrate with an initial potassium con centration (11.0g l(-1)) close to the optimum value showed time predicted d ecrease in micro-organism activity following potassium removal using the mo dified membrane. However, molasses from most Australian sources has a potas sium concentration substantially higher than the optimum value when diluted for use as a substrate and in that case fermentation performance would be expected to be enhanced by potassium removal. Also, it was shown that the r ate of fermentation of molasses could be increased by macromolecule removal using an ultrafiltration membrane with a nominal molecular weight cut-off of similar to 300 000 Da. (C) 2001 Elsevier Science B.V. All rights reserve d.