Mother's Hop Utility Scale

Posted on Aug. 28, 2018, noon

We want to take a moment to explain a new development that you will be encountering with the new packaging on our beers. Mother’s Hop Utility Scale (HUS) is a graphical representation of our approach to using hops in our beers. Further, you may notice that in the adoption of the HUS we’ve abandoned the IBU in describing our beers. Why this breach of craft orthodoxy? Read on.

One of the great challenges facing a craft brewery is communicating about your beer. Seemingly inumerable styles, each with infinite variations make for a broad experience for beer lovers. At times, also dauntingly broad. Sensory descriptors are there to help guide us on this journey: resinous hop linger, citrus aromas, roasted malt bitterness, clove-like esters, or creamy mouthfeel. These descriptors can narrow down the choices to the right beer for the right mood. By and large, this vocabulary is based on subjective experience. It tends toward qualitative language. There is, however, quantifiable information about beer that can be helpful. Alcohol by volume (ABV) gives a specific and useful value: an 11% imperial stout may not be the ideal choice for an eight hour canoe float. Maybe that 4.8% pale lager is the ticket.

The other quantifiable measure that’s gained traction in craft beer is the International Bitterness Unit, or IBU. You are likely familiar with the IBU: a numeric value purported to describe the level of bitterness in a particular beer. As the craft beer industry matured and American IPAs began to proliferate, the IBU became a badge advertising the muscularity of hop bitterness among competing breweries. The higher the IBU rating, the more prominent the palate-zapping hop bitterness. Pretty simple.

In fact, too simple. Beer is a complex interplay of so many elements, reducing things to a single number seems suspect. In the case of hop character, this is especially true. Many factors play a role in the perceived bitterness of a beer: malt character and residual sugars can temper hop bitterness. And what of hops employed exclusively for aromatic and flavor purposes? Contemporary trends in craft have blown wide open a world of hop forward beers with negligible hop bitterness. Dry hopping in particular brings much to the aroma and taste of a beer without affecting its IBU.

To get a grip on why IBUs strike us as insufficient in describing hop character in our beer, let’s take a look at how the International Bitterness Unit came to be and exactly what it measures.

And to do that, we need to start with the chemical content of the hop flower. Hop flowers have two basic categories of compounds of interest to brewers and beer drinkers: alpha acids, which provide bitterness, and hop oils, noted for a range of aromas and flavors. Which component of the hops being utilized is controlled in multiple steps in the brewing process. Hop compounds undergo transformation in the boiling wort of the kettle. With first addition hops in the boil, alpha acids are converted into iso-alpha acids which are the principle source of bitterness in the finished beer. The extended boil drives off the highly volatile essential oils, meaning we do not get much flavor or aroma from such additions. First hop additions, then, establish the basic bitterness. Further hop additions added at later stages in the boil do not isomerize alpha acids as fully, contributing less bitterness per pound added. Nor do they boil off the volatile oils. Late stage boil additions, then, contribute most directly to aroma, but not bitterness. Likewise, hops added post-boil, either in the whirlpool or post-fermentation in dry hopping, aim to utilize hop oils for their contribution to aroma and flavor. Radically simplified: the bitterness of, say, a classic American IPA owes to iso-alpha acids; the intense citrus and/or resinous aromas to hop oils.

If you’ve surmised by now that the IBU scale seeks to measure the amount of iso-alpha acids (IAAs) in a finished beer, you get a gold star. It does so by measuring the amount of ultraviolet light (at a wavelength of 275 nanometers, if you’re curious) absorbed by a sample of beer. IAAs absorb light at this wavelength, so the absorption of this ultraviolet light in a beer sample corresponds to the amount of IAAs in said sample. The amount of IAAs correlate to perceived bitterness. At least, theoretically. To make things more complicated there are also bitterness compounds that can come from hops that have nothing to do with IAAs, and the act of dry hopping itself can even directly reduce IAAs in a beer.

Let’s set aside our textbooks and move on to our beef with IBUs as they relate to beer you drink on a daily basis. First, the IBU scale was developed in the 1960s on your standard industrial scale domestic lager. The difference between those beers and today’s craft cannot be understated. Advances in hop breeding, processing, and storage have altered tremendously both the quantity and quality of hop compounds finding utilization in a contemporary brewhouse. IBUs in a landscape of virtually identical thin and bone-dry lagers may have made sense then, but what sense do they make in today’s kaleidoscopic world of innumerable styles? As a calculation, IBUs ignore any context of the particulars of a specific beer. They do not account for malt body or residual sugar that may balance or overwhelm perceived bitterness (our coveted barrel aged stout boasts 55 IBUS and we’ve yet to encounter any drinker who notes it for its bitterness). And they certainly do not account for the intensity of hop flavor and aroma that contribute to the hop character of today’s aggressively dry hopped IPAs and tropical pale ales. When Mother’s considers the hop character of a beer, we’re paying attention to the entire range of sensation that hops bring to beer, of which IAAs are but a single factor. In short, IBUs are simply inadequate to describe the beauty of what hops bring to beer.

Why then has natural selection not run its course? Should not so poor a formula have faded from use altogether? The fact is that IBUs are useful. To brewers. Calculating predicted IBUs remains indispensable for maintaining consistency across multiple brews of a single recipe. As a tool for establishing recipes or processes, IBUs are valuable. But we think that value translates poorly to the pint sitting in front of you. And that is why Mother’s is choosing to leave IBUs where they belong: in the brewhouse.

Which brings us to the ultimate point of this post: what we hope is a more informative approach to the hop character of Mother’s beers. The Hop Utility Scale tells you the amount, in pounds per 60 bbl batch, of hops added for bitterness and the amount added for flavor and aroma. The total amount for kettle hop additions clue you in on our utilization of alpha acids. If that was all you needed to know, then maybe a traditional IBU would be sufficient. But knowing the amount of late addition and dry hops, where we’re getting the most out of those hop oils, tells so much more of the story. A comparison of these two numbers gives a more complete picture of the total hop character for each of our beers. We include this information on all of our new six packs. Take our pale ale Hands Down, for example: we add zero pounds of hops for bitterness and 137 pounds for flavor and aroma. If you’re in the mood for righteous aromas of lemon and blackberry without hop bite, we’ve got your number. Lil’ Helper, our flagship IPA, uses 18 pounds of hops per 60 barrel brew for an appreciable bitterness. But it also gets 83 pounds of hops for the big citrus and pine aromas American IPA drinkers crave. The Hop Utility Scale provides a handy reference when looking to determine the balance of hop bitterness and hop flavor you want from your beer.

It also provides a scatter plot which illustrates how all of our beers relate to each other in terms of hop character. Both Doozy! and Sunshine Chugsuckle employ massive amounts of hops but are in no way the same beer. Comparing them on the graph gives some expectation about how the hops express themselves in the glass: assertive bitterness in Doozy! and riotous juicy hop flavor in Chugsuckle. The graph provides an overall snapshot of what we’re up to at our brewery.

In the end, your Mother’s hopes this additional information inspires confidence when choosing the right beer for the right mood. Or maybe inspires curiosity about a particular beer or style you may be unfamiliar with. Craft beer culture values education and enlightenment about brewing. The Hop Utility Scale isn’t an anti-IBU ideological statement, but it is another step in our mission to shine a little light on the magic that happens in brewhouses around the world. Beer is a fantastic balance of art and science, but it needn’t be an impenetrable mystery. Informed drinkers are happy drinkers. And happy drinkers are what keep us motivated to share the love. So check it out. Take a look and then take a drink. Discover what 137 pounds of hops means when it hits your tongue. Bottoms up, lovers.

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