A guided tour through the art, science and history of our favourite 7,000-year-old beverage with beer columnist Brent Milcz.
In part one of our journey from grain to glass, we discussed malt and what it contributes to a beer.
This week our topic is the yin to malt’s yang, and the focal point for the craft-beer-loving masses of late – hops.
Hops are the cones of the flowering plant humulus lupulus, which grow on a bine rather than a vine. The difference is that hops climb without the use of tendrils, helixing (to invent a word) their way around their trellis.
At the peak of growing season, a bine can grow up to a foot in a day—so fast that you can literally see it growing in an afternoon.
Like grapes, hops have terroir, and growing the same hop variety in different regions and conditions will give the plant different characteristics. For ease of use in brewing, hops are typically shredded and pressed into uniform pellets.
Hops bring several things to a great beer, but their primary purpose is to provide balance. As discussed last time, malt provides our sugar from fermentation.
This sugar is converted into alcohol by our yeast – bless their little single-celled souls – but it is rare for a yeast strain to metabolize all of the sugar provided.
That residual sugar left behind by the yeast would leave us with a cloyingly sweet beverage if we did not balance it out with bitterness.
This is where hops come in.
Before the widespread use of hops, something called gruit (“groo-it”) was used. Gruit is a combination of herbs such as yarrow, horehound, mugwort, and some other more or less silly-sounding names.
The beverage made from these herbs is also called gruit, rather than beer. In the Middle Ages in most of Europe, gruit was your only option at the pub.
The Catholic Church, however, had proprietary knowledge of, and controlled distribution of the favoured gruit mix of the time.
Switching to hops was a way for brewers to get out from under the thumb of the Church, and it was later discovered that hops provide a preservative effect to beer that gruit did not.
Hops have an anti-bacterial quality that works in conjunction with beer’s alcohol and low pH to create a microbiologically stable beverage that is not prone to dangerous spoilage.
When adding hops to a beer, depending on the timing of our additions, we can impart bitterness, flavour or aroma to the beer.
By pitching our hops into boiling wort, we will isomerize alpha acids, the active bittering component in hops.
The longer they are exposed to boiling wort, the more bitterness we can expect in the beer (measured as IBUs – or international bitterness units).
Some hops have higher alpha acids than others.
By adding hops near to or at the end of the boil we’ll get the characteristic hop flavours and aromas we recognize (piney, spicy, earthy, citrusy). These come from the volatile essential oils in the hops.
If these oils are exposed to a vigorous boil for too long, they will flash off and we will lose these flavour and aroma qualities.
To avoid this flashing off effect, we can also add hops directly to our fermenting beer in a process known as dry-hopping.
Dry-hopping preserves a great deal of aroma, and is a technique widely used in IPAs to provide a potent nose.
Brent Milcz is the head brewer for Carnarvon’s Boshkung Brewing Company.