Troubleshooting the causes of high carbon dioxide content in bottled beer: a case study of Nile Breweries Limited, Jinja Plant, buikwe district, Uganda

Abstract

This research project is written as final year project of bachelors of Science in industrial chemistry at Makerere University. The project focuses on troubleshooting the causes of high carbon dioxide content in bottled beer in order to find a long-lasting solution to existing carbon dioxide “out of spec” conditions in beer for the case of Nile breweries limited. Carbon dioxide is a critical ingredient of beer and is also used to pre-fill each bottle before beer is added. It is produced naturally during primary and secondary fermentation and can artificially be added to beer by carbonation. The carbon dioxide added to beer must be of the purest form available and care must be taken not to dissolve more carbon dioxide in beer than the specification allows. Carbon dioxide non-conformances cause problems with the beer package and packaging process, and greatly affect the plant performance leading to reduction in beer quality and losses. The study scope of this project is limited to part of beer production process starting from beer filtration to pasteurization. A review of literature reveals that most of carbon dioxide “out of spec” conditions occur during and after the filling process. Carbon dioxide solubility in beer depends on temperature and pressure, and its partition between the liquid and head space is governed by Henry’s law. The combined CO2/O2 Gehaltemeter and Orbisphere 6110 total package Analyzer were used to measure temperature and carbon dioxide in bright beer and packaged beer respectively. Analysis of collected data have been performed in Microsoft excel and the results showed that the average bright beer temperature measured was 3.07oC against the theoretical value of ± 1oC with the filler being operated at average of 2.19 bars. The extra carbon dioxide content (0.18 V/V average value) pick up at the filler is suggested to be the main cause of carbon dioxide non-conformances in bottled beer. The collected data revealed that the concentration of carbon dioxide in bottled beer was out of 0.08 V/V higher than the theoretical upper limit value of 2.75 V/V. Since filtration process is usually the last opportunity to make corrections to the beer before packaging, I highly recommend to always target lower Carbon dioxide in bottled beer during carbonation. This will guarantee conformity of concentration of carbon dioxide in packaged beer before a comprehensive engineering failure analysis of the filler is done and its carbon dioxide regulation valve is fixed.