Hop Sensory Analysis

Hop Sensory Analysis


October 23, 2015 / Brewing

During late summer, growers throughout the Pacific Northwest begin the process of hop harvest, where bines are cut, ripe cones are picked, and hops are processed at each farm. The hop cones are kiln-dried for a set number of hours between 125 – 140F, cooled for a 24-hour period, and then pressed into 200 pound bales. A shipment of bales, known as a lot, is then delivered to Yakima Chief – Hopunion (YCH HOPS). Each bale in a lot is labeled with a two-letter code for variety, the crop year, the grower ID number, and the lot number. Once a lot arrives, we check each bale to make sure that the moisture is between 8.5 -10.5%. Moisture too high above or below this threshold can cause the hop bales to slowly heat up over time and possibly catch fire.

From each lot of hops that is delivered, we pull a sample (or plug) from randomly selected bales by taking a small cross-section called a “brewer’s cut” that we use to represent the lot. For small lots we randomly choose one or two bales, and for large lots we choose three or four. The brewer’s cut is graded based on hop sensory metrics by YCH staff and brewers who visit during harvest. These brewers represent a well-rounded sample of breweries from all over the world, reflect a broad range of perspectives, and help communicate their needs for the benefit of the entire brewing community. The comments and descriptors regarding each brewer’s cut is provided back to our growers in a post-harvest grower meeting.

Similar to beer, hop sensory analysis goes beyond calling a hop sample “hoppy” and is the process that we use to evaluate each hop sample that is delivered to YCH HOPS. The attributes that we look for are: color, the amount of lupulin, shatter, aroma, and the amount of onion/garlic that a person can detect. We use a 1 to 5 scale for each metric, where 1 is low and 5 is high. These numbers are then used to determine a composite score so that we can compare lots.

Color

There is a great amount of information that you can perceive by looking at the color of hops. Generally, hops should have a vibrant green color depending upon the variety. Noble and low alpha hops typically look pale green and higher alpha hops, like Nugget, will look deep green. If hops become over-ripe, sunburned, or unhealthy, they eventually turn yellow or brown in color. Generally, a yellow or brown brewer’s cut gets scores of 1 or 2, while deep green, healthy-looking cones get scores of 4 or 5.

Amount of lupulin

When looking at the sides of a cross-section of hops, you can quickly see how full and big the lupulin glands are in each variety. Some hops will have very small lupulin glands and look thin and narrow; these are generally low alpha hops. The high alpha hops will have big, fat glands and look very yellow in comparison. The amount of lupulin within a brewer’s cut is greatly affected by the growing conditions of that year, and will vary from field to field. Typical varieties that score in the 4 to 5 range are Citra®, Magnum and CTZ, because they have such high amounts of oil, while noble hops often score 1 or 2 because of they contain a low amount of oil.

Shatter

Shatter is simply a measure of dryness. A hop cone picked from the bine during the optimal harvest window is highly flexible, soft, and generally very tough to break apart when rolling it between your palms. In contrast, overly dry cones can become brittle causing the strigs to break easily, the bracteoles to fall off the strig, and/or the hops to become powdery. When we look at shatter, we take a handful of hops and rub them between our hands, focusing on how easily the cones break apart. We are looking for hops with high amounts of oil, which will feel “wet” and quickly cover your hands in lupulin.

Aroma “What do you smell”?

Once we’ve rubbed the handful of hops between our hands, we bring them up to our nose and inhale deeply. A lot of people are familiar with this part of the process. The typical aromas that we talk about are citrusy, piney, minty, or fruity, but we also make an effort to take it one step further and be more specific. Is the aroma orange or grapefruit? Peach or melon? Pine or cedar? We also talk about the intangibles such as, “do you like the aroma or not?” Whether individuals have specialized sensory training or not, all YCH HOPS staff members have the opportunity to participate and offer their feedback. A brewer’s preference also plays a big part in sensory analysis, as some brewers may want dank, fruity hops or mild, minty hops depending on the recipes they have developed. This is why it is difficult to replicate beer recipes despite using the same ingredients; the amount of oil, harvest date, and growing region all play important roles in distinguishing differences in aroma from lot to lot.

Garlic/Onion

Onion and garlic aromas are typically not desired, because they are usually good indicators that the hops are over-mature and beginning to oxidize. These aromas can be highly volatile and dissipate rather quickly, or be the only odor that a person can perceive. Any hop variety can develop garlic/onion aromas but generally high alphas are affected more often.

Rubbing and sniffing hops has been used as the traditional method to determine if hops showcase the desired characteristics you want in your beer, or as a means to determine if there are any off-flavors and/or aromas that you may want to avoid. The sensory analysis metrics that we use are just one of the ways we evaluate hops here at YCH HOPS. They provide important data that we can use to track hop quality at a field and farm level, and provide detailed information that we can deliver directly from brewers to growers. Together, this is just one more way that we connect our family farms with the world’s finest brewers.

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