Beer is a beverage that is produced in a multistage process, where some stages of that process are intentionally influenced by microorganisms, while at other stages of the production process microorganisms are actively discouraged. Most of the intentional microbial activity is facilitated by yeast; however bacteria also play an influential role in beer production. This paper will describe the beneficial role of bacteria in the beer production process (the Good), but will also pay due attention to the negative influences bacteria might have on the quality of beer as a commodity (the Bad), and the properties of beer that have given it the status of an inherently safe food for human consumption with regards to disease‐causing bacteria (the Ugly). Copyright © 2013 The Institute of Brewing & Distilling

This research aimed to develop a simple and effective method for analyzing thiamin (B(1)), riboflavin (B(2)) and their respective vitamers by high performance liquid chromatography (HPLC) in fermented alcoholic beverages. The method developed here employs a phosphate buffer/methanol gradient elution on a single reverse phase column, coupled with independent fluorescent detection regimes. It also employs a precolumn derivatization to convert thiamin to thiochrome via an alkaline potassium ferricyanide solution. The method described here allowed a spike recovery of better than 97%, with a typical linear detection range (R(2) ≥ 0.9997) between ≤ 5 and ≥ 500 μg/L for all vitamers studied. Lager style beers were found to contain significantly (p < 0.001) less thiamin than other tested styles of beers (lager, 35.7 μg/L; ale, 88.3 μg/L; stout/porters, 104.4 μg/L; wheat beers, 130.7 μg/L), which may be due to the raw material and extensive processing that occurs for this style. There was no statistical difference (p = 0.608) between the riboflavin content of each beer style. Furthermore, wines and ciders contain less thiamin and riboflavin than beer, which is also likely to be due to the base materials used and the differences in processing steps to produce these beverages.

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Wort production contains a number of processing steps that are aimed at the optimal extraction of nutrients from malt, including vitamins. This research revealed that the different wort production processing steps imposed different influences on the thiamine and riboflavin vitamer content of the final sweet wort. These vitamins play vital roles within yeast metabolism, where they act as enzyme cofactors. As such thiamine vitamers play a crucial role in many decarboxylating enzymes, while riboflavin vitamers play an integral role in energy production and redox maintenance. While mashing releases valuable starch into the liquor, both thiamine and riboflavin are also extracted. The extraction of these vitamins is the greatest at 65°C and is indirectly linked to the amylase activity. When the starches are broken down during mashing, the thiamine and riboflavin vitamers are gradually released into the mash liquor. The boiling and trub removal (whirlpool) processes impose losses in both vitamins owing to the high temperatures exhibited during these stages. While hop pellets were shown to contribute a small proportion of the vitamers studied, the use of kettle finings caused a significant reduction in both thiamine and riboflavin vitamers.

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