Alternative Techniques for Beer Decarbonation. Marc D. Constant and John E. Collier, Technical Center, Miller Brewing Co., Milwaukee, WI 53208. J. Am. Soc. Brew. Chem. 51:0029, 1993.

The sample preparation for many beer analyses, including the recently adopted Servo-Chem Automatic Beer Analyzer method for alcohol and original gravity, requires decarbonation of the sample. The present ASBC method Beer-1A requires that samples be shaken in a flask until gas no longer escapes. This procedure can efficiently remove carbonation but has the potential to result in lowered alcohol levels. The decarbonation of beers in an ultrasonic bath can provide samples with good alcohol retention but with residual carbonation sufficient to affect pH and real extract. Gas purging, mechanical shakers, and gas-permeable membrane decarbonation techniques were investigated and found to be superior to bath ultrasonication for the removal of carbon dioxide. Methods using a bench-top rotary shaker and baffled Erlenmeyer flasks were preferred for routine multiple sample preparations and for efficiency in decarbonation and alcohol retention. An infrared carbonation analyzer provided a convenient means to monitor residual carbonation levels. The measured carbonation effect on real extract was found to be about 0.11% (w/w) per volume of carbon dioxide.

Keywords: Alcohol, Carbon dioxide, Infrared analyzer, pH, Real extract, Sample preparation, SCABA