VIEW ARTICLE    DOI: 10.1094/ASBCJ-53-0063

Continuous Gas (CO₂) Stripping to Remove Volatiles from an Alcoholic Beverage. J. A. Scott and D. E. Cooke, School of Chemical Engineering, University of Bath, Bath BA2 7AY, England. J. Am. Soc. Brew. Chem. 53(2):63-67, 1995. Accepted November 14, 1994.

Tower fermentors have been designed such that naturally evolved CO₂ can be recirculated for continuous extraction of ethanol and other volatiles from beverage fermentation. Volatiles carried over in the gas stream are recovered by condensation at -4°C This has been demonstrated to be a potential ethanol-removal procedure for production of reduced alcohol cider (apple-based) beverages. Other volatiles isolated from the fermented fruit-based medium may be returned to the broth, but they are also a potentially important source of naturally produced flavor and aroma compounds, useful to drug, food, and other industries. Stripping also modifies the total quantities (medium plus condensate) of ethanol, isobutanol, isoamyl alcohol, and ethyl acetate. The exact impact (net increase or decrease), depends on fermentation temperature and original gravity. The fermentation period for ciders is long (up to 21 days), and stripping caused an increase in the dissolved CO₂ level and decreased media pH, but the progressive removal of water from the fermenter (15% of initial volume at 25°C) did not appear to place osmotic stress on the yeast. Keywords: Carbon dioxide, Ethanol extraction, Stripping, Volatiles