|A"Barley Harvest" is the cutting, threshing, separating, and cleaning of individual barley grains from the mature
barley plant. Depending upon variety and climate conditions, barley grows from 12 to 48 inches tall. The tightly
packed spikes or ears of seed kernels can take from 40 to 55 days to fully ripen after flowering and droop down
when ready to harvest. Growers closely monitor and test mature plants for grain size, protein content, and
moisture. For malting barley, the moisture content at harvest tends to be between 12% and 17%, whereby
12.5% is considered ideal.
Harvesting by “direct head cutting” involves cutting the ripened ears off close to the stem, high on the plant, to
minimize debris. The crop is then threshed to separate the individual grains from other plant material and cleaned
of foreign matter. Swathing, by contrast, involves cutting the plant low, leaving a short bed of stubble that supports
the long interlaced stems and ears off the ground, where the crop is allowed to dry in the field before being
gathered and threshed.
Excessive handling, however, can break, crack, or abrade the barley kernel, rendering it useless to the
malt house and brewer. Dry grain, properly stored, will last for months or even years.
A Mash Fork was a traditional brewing tool used to manually mix the mash. It was used during mashing in to
ensure even heat distribution and uniform viscosity and to break up dough balls formed during mashing.
Usually made of a hardwood such as beech or maple, a mash fork, with its open lattice design, was able to
move easily through a thick mash without risk of breaking.The mash fork played a role similar to that of the
lauter rakes in a larger modern brewery.
Before the introduction of what we think of as modern brewing equipment and techniques, brewers had to make do
with undermodified and inconsistently milled malts and poor temperature control, sometimes leading to gummy
mashes that would not run off properly. Skillful use of a well-made mash rake could make the difference between a
successful brewing session and a useless mass of wasted grain. Today, the mash fork is largely a thing of the
past, although the occasional enthusiastic craft brewer still has one made.
They also live on as an evocative symbol of traditional brewing and form part of many heraldic-style symbols
used by brewer’s guilds and associations, including the Master Brewers Association of the Americas.
Zymomonas is a Gram-negative beer-spoilage bacterium. It has a notorious legacy as a historic contaminant of
breweries. Zymomonas bacteria are distinguished by their short rods and very active polar flagellae. These give
the cells a strong motility indicated by their rapid movement under a microscope.
This bacterium is distinctive in that it can ferment glucose, fructose, and sucrose—as can brewers yeasts—but it
cannot ferment maltose. Also like yeast, it produces ethanol and carbon dioxide, but at a more efficient rate.
However, its fermentation by-products include acetaldehyde as well as hydrogen sulphide, which is rapidly
converted into objectionable vegetal flavors. Zymomonas is also resistant to acidic conditions and may thrive
together with acetic acid bacteria.
A Zymomonas infection can therefore result in a very sour beer. Because Zymomonas does not flourish in a
habitat with high levels of maltose, it does not grow well in wort. As soon as yeast has converted maltose into
alcohol, however, Zymomonas can become a problem and spread quickly. Once Zymomonas has colonized
brewery equipment, it is difficult to eradicate. Sometimes contaminated equipment even needs to be replaced.
Today, Zymomonas has become relatively rare in breweries, mostly because of much improved hygiene
management and because priming with sugars is rarely employed nowadays.
Hope you found this month's column of interest. If you have any questions about beer or brewing
or just want to submit a word for me to discuss here just e-mail it to me.
Thanks and Cheers!
|Barley Harvest // Mash Fork // Zymomonas
|A new column by
|Jack O'Reilly attended the
famous Siebel Institute/ World
Brewing Academy in Chicago.
|I'm very excited to be part of the BeerNexus team. I think my many years in the
beer business both as a brewer and manger will enable me to explain and
investigate many topics of interest for those who really love craft beer.
Hope you join me every month.
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|Techniques and insights
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