The vacuferm process: A new approach to fermentation alcohol

A Vacuferm process is envisaged in which full-strength clarified molasses is fed continuously to the fermentor - still along with a recycled cell cream of aerobically grown yeast. The yeast would then need no added sterols or oleic acid. Since it is probably impractical to use an expensive vacuum fermentor to remove the last traces of sugar and alcohol from spent beer, the latter could be aerated at atmosphere pressure to provide additional yeast growth. After centrifuging, a portion of the aerated yeast cream could be returned to the fermentor as continuous inocolum; the remainder would be dried for sale as an animal feed. Alternatively, use of a crude nutritional supplement, such as wheat germ oil, would make it unnecessary to install a separate aerobic cell propagator. An obvious process improvement would be to use thermotolerant yeasts that can ferment at >45/sup 0/. Their use would permit higher pressures in the fermentor. The heat of fermentation in this process is used directly for distilling off alcohol, unlike the conventional process where it must be removed with cooling water. This saving in energy represents about 7% of the latent heat required for distilling off the alcohol. However, in the Vacuferm processmore » a 3-fold higher sugar concentration can be fermented in only 1/3 more time needed in a conventional process.« less