Beer : Health and Nutrition

The Basics of Malting and Brewing 67
kilned quite gently, whereas those going into the somewhat darker ales are subjected
to more heating. The very dark colours in stouts come from the incorporation into the
grist of a proportion of malt that is roasted intensely.
One of the biggest concerns with the intense heating of grain raised over 20 years
ago was the risk of developing nitrosamines (Havery et al. 1981). These molecules have
been demonstrated to be carcinogenic in model animal systems, but not so far for man.
They are primarily produced when precursors in grain, notably hordenine, react under
heat with oxides of nitrogen, which tend to be present in the atmosphere, especially
in regions with heavy industry. The malting and brewing industries responded with
tremendous alacrity to the ‘scare’ and within a very short period of time nitrosamine
levels had been reduced to very low levels (Sen et al. 1996, and see Chapter 5). The
key change in practice was the use of indirect kilning such that the nitrogen oxides no
longer contacted the malt.
Brewing
Brewing (and malting) is nowadays conducted in well-designed and highly hygienic
facilities, for the most part fabricated from stainless steel. The equipment is repeatedly
cleaned using regimes of acid or caustic, followed by thorough rinsing with clean water
and perhaps a sterilant of the type that would nd use in the domestic kitchen.
In the brewery, the malted grain must rst be milled to generate relatively ne
particles, which are then intimately mixed with hot water in a process called mashing.
Mashes typically have a thickness of around three parts water to one part malt and
contain a stand in the vicinity of 65°C. At this temperature the granules of starch are
converted in a transition called gelatinisation into a ‘melted’ form that is much more
susceptible to digestion by amylases. These enzymes are developed during malting, but
only start to act once the gelatinisation of the starch has occurred in the mash tun. Some
brewers will add starch from other sources, such as unmalted barley, maize or rice, to
supplement that from malt. These other sources are called adjuncts. It may be necessary
for the brewer to add extra enzymes at this stage, to help deal with some of these
adjuncts. Many brewers, though, outlaw the adoption of such ‘exogenous’ enzymes,
even though they are fully recognised as safe and are derived from harmless organisms,
e.g. Aspergillus and Pencillium, which naturally thrive throughout nature, including on
the surface of grain (Flannigan 2003).
After a period typically of one hour, the liquid portion of the mash, known as wort, is
recovered in a ‘lautering’ or ltration operation and run to the kettle where it is boiled,
again typically for an hour. Boiling serves various functions, including sterilisation of
wort, precipitation as ‘trub’ of proteins and tannins (which would otherwise come out of
solution in the nished beer and cause cloudiness), and the driving away of unpleasant