The Basics of Malting and Brewing: Product Safety and Wholesomeness

The fundamental shape of the processes by which beer is made has not changed for many generations [see Bamforth (2003) for a general introduction and overview, and a full glossary of brewing terms]. However, the control and predictability of those processes has improved. Beer nowadays is invariably a highly consistent consumable, closely controlled for the ef ciency of its production and its safety. There is little that is hit-and-miss about the making of beer. Despite its reliance on agricultural products (barley, sometimes other cereals, and hops) the understanding of the process means that seasonal and regional vagaries can be overcome such that the taste, appearance and composition of a beer are generally consistent from batch to batch. There is no such thing as a vintage in brewing.
Accordingly, the customer should realise as they explore their local supermarket shelves that one of the most consistent and reliable products to be had is the beer. It is also one of the safest, as we shall see.

Chemical beer?
The brewing of beer is complicated. The vast majority of beers comprise at least 90% water, with ethanol (it is customary to use 'alcohol' synonymously for this one alcohol - although there are other alcohols in beer) and carbon dioxide being quantitatively the next major individual components (Table 3.1). Beers also contain a wide range of chemical species in relatively small quantities that determine the properties of the beer in respect of appearance and avour.
Malting and brewing are processes designed to maximise the extraction and digestion of starch and protein from barley, yielding a highly fermentable extract that is known as wort. The processes are also designed to eliminate materials that can have an adverse effect on beer quality, such as the haze-forming polyphenol from barley and hops and the lipids and oxygen that, together, can cause beer to stale.

Aflatoxins originate from some members of the genus Aspergillus, namely Aspergillus avus, A. parasiticus, A. nomius and A. ochraceoreseus (Moss 2003). (It will be noted that these don't include the strains such as A. oryzae that have a role in the production of alcoholic beverages such as sake or as a source of exogenous enzymes for brewers.) The most commonly a atoxin-contaminated foods are corn (maize) and peanuts, but all cereals may be affected. Infection is most commonly associated with post-harvest spoilage, when storage is under inapproporiate conditions of temperature and moisture.
Pesticides have real value in this context. Nonetheless there has been in-depth inves­tigation of alternative ways of treating grain, particularly during storage, such that it does not develop infection. These studies have included the use of anaerobic storage (Baxter & Dawe 1990). Where pesticides are used much will be largely washed off the surface of the grain during steeping (Miyake et al. 2002).
It must be emphasised that authorities in most countries have regulations and sys­tems for controlling the nature of pesticides that may be used, and those pesticides have been widely screened for their environmental and health impacts. Any perceived risks of using them are grossly outweighed by the very real problem that can accrue in any cereal from contamination with those micro ora capable of producing mycotoxins and ochratoxins (Petzinger & Weidenbach 2002). One such substance is deoxynivale-nol (DON), which is produced by the fungus Fusarium (Wolf-Hall & Schwarz 2002). Brewers (and therefore maltsters) set rigorous standards for the level of DON in barley
and malt, and will not use grain that contains it. Fusarium infection is a bigger risk in wetter climates. Thus it was virtually unheard of in North America until the mid-1990s, when a substantial problem was encountered. The reason was a movement away from the burning of straw stubble after grain had been harvested. This burning, outlawed for supposed environmental damage, had served the valuable function of destroying Fusarium spores. Once burning was banned, it meant that the Fusarium was enriched in the soil and readily available to spoil crops the subsequent year.
Woller and Marjerus (1982) and Marjerus and Woller (1983) failed to detect any mycotoxins in a diversity of beers (detection limit 1-2 ng/L). It is not impossible to nd nite levels of mycotoxins - see for example Payen et al. (1983). However, provided all parties adhere to the strictest standards of hygiene from eld to glass, and the grain is maintained under the appropriately low levels of moisture and temperature, then this is not an issue.