FERMENTATION OF DATE EXTRACTS TO ETHANOL AND VINEGAR IN BATCH AND CONTINUOUS MEMBRANE REACTORS

The sugars in extracts of dates (Phoenix dactylifera) were converted into ethanol by S. cerevisiae. At an initial cell concentration of 10 g l-1 in a batch process, fermentation of juice with 98 g l-1 sugars (49.5 g l-1 glucose and 48.5 g l-1 fructose) was completed in 12 h, and in 20 h with 138.3 g l-1 sugars. With the membrane recycle bioreactor, with a cell density of 150 g l-1, maximum productivity with complete sugar utilization was 25 g l-1 h-1 with an ethanol concentration of 68 g l-1. This is more than eight times better than the batch process. The subsequent production of acetic acid from the fermented date juice was conducted with Acetobacter aceti. In a membrane recycle bioreactor, productivity was 10.8 g l-1 h-1 at an acetic acid concentration of 45 g l-1. This is more than 20 times higher than that of a batch process.