If you’ve ventured into homebrewing, you’ve likely come across the alpha and beta acid content on hop packets. It’s not a reference to noughties college movies - Alpha and beta acids are the dynamic duo that hold the key to beer’s bitterness, flavour and shelf life. Meanwhile, the hops aromatic charm and delicate tastes come from essential oils with quirky names.
Think of alpha acids as the superheroes of bitterness, swooping in to give that fantastic kick we adore in a hefty WCIPA. Boil them in the wort, and they shape-shift to dissolve into the liquid. Sadly, they burn bright and fast, fading quickly and sometimes living long enough to become the villain, leaving us with rancid, cheesy flavours if not kept cool.
On the flip side, beta acids hardly dissolve during the boil. These quiet sidekicks make themselves known in beers with a long shelf life, providing a slightly harsher bitterness as alpha acids take a back seat.
Essential oils, though <3% of the hop weight, are the real MVPs - essential to the fruity allure of a NEIPA and the earthiness of an ESB. While these oils evaporate quickly in the boil, this is where dry hopping makes its appearance, allowing oils to disperse into the liquid without the high temperatures altering the alpha acids’ shape and creating extra bitterness.
The three main oils (although there are hundreds) are myrcene, caryophyllene and humulene. Caryophyllene and humulene were the stars of the show for centuries, being prized for their spicy, floral notes in just about every European and British style of beer, while myrcene has seen a rise in recent years with the Yanks opting for more citrusy and piney notes.
Cheers to our bittering heroes and the essential oils that keep us coming back for more!