Beer taints associated with unusual water supply conditions.
Jackson, A., Hodgson, B., Torline, P., de Kock, A., van der Linde, L. and Stewart, M.
In 1988 an unusual off flavour described as "inky" or "medicinal" was reported to occur in certain beers produced by South African Breweries. At the same time, the laboratory at the brewery concerned reported unusual chromatographic peaks appearing during routine diacetyl analysis, which were traced to the water used in the analytical procedure and eliminated by boiling it with activated carbon. This led to the installation of activated carbon filters for the brewing liquor, which suppressed the problem but necessitated frequent renewal of the filters. An investigation into the source of the taint was conducted in the hope of finding some means of eliminating it. It was found that the reservoirs from which the brewery's liquor supply originated had been very low for several years as a result of persistent drought, leading to the accumulation of organic matter. Moreover, the remoteness of the reservoirs and the long route from source to consumption necessitated heavy chlorination at source to maintain freedom from microbiological contamination. In conjunction with local geological conditions, which brought minerals rich in iodine and bromine into contact with the water, this gave rise to the formation of significant quantities of trihalomethanes. Further investigations, still incomplete at the time of writing, indicate that the taint is probably caused by one or more unusual iodinated trihalomethanes which cannot yet be precisely identified or accurately analysed.
Keywords : beer brewing liquor contamination iodine off flavour organic compound