Xueqian Su: How to know a good hop when you smell one
This story was written in the spring of 2021 by GRAD 5144 (Communicating Science) student Jennifer Brousseau as part of an assignment to interview a classmate and write a news story about her research.
She may not be a huge fan of beer, but graduate student Xuequian Su knows a good hop when she smells one.
Su is a Ph.D. student in Virginia Tech’s Department of Food Science and Technology focusing on the aroma chemistry of beer hops. Many people have heard the term “hoppy beer” but may be unaware of what a hop actually is. Hops are the flowers of a plant called Humulus lupulus, and they are one of four main ingredients in beer. Hops help beer maintain its freshness and foamy state, while adding that “hoppy” aroma, flavor, and bitter taste to beers.
But what exactly is this hoppy aroma? And how can hop farmers best retain that aroma as they dry their products to send to brewing companies?
These are questions that Su is hoping to learn more about in her research. She is investigating the different odors of two varieties of hops from Virginia, the Cascade hops and the Chinook hops. While the main hop producers are in the Pacific Northwest, Virginia has become a bigger player in the hop-growing industry over the past several years. With samples of Cascade and Chinook hops from three locations across Virginia, Su works to detect the components of the smells--such as citrus, mushroom, and berry--of each variety.
She is also experimenting with different hop-drying techniques to find a method that preserves the hoppy aroma and is effective for small-scale brewers. The three drying methods most employed by hop growers are oven drying, freeze drying, and dehydrating the hops. Larger companies tend to dry hops in ovens, whereas smaller brewers use the freezing or dehydrating methods.
After drying the hops using each of these three methods, Su uses a machine to absorb the aromas from each dried hop sample. She then detects the flavors of each aroma using both an aroma detection machine and an old-fashioned tool--her nose! Fun fact: Su has already sniffed about 65 hop samples throughout the course of her experiments. While her nose is easy to operate, the aroma detection machine has often presented challenges, which Su has navigated like the expert she is.
Through her experiments, Su found that dehydrated hops retained their aroma better than did the freeze- or oven-dried samples. She attended a Virginia Agricultural Meeting in May of 2021 to share her findings with hop farmers and hopes to continue advising the food industry with her work on aroma chemistry after she finishes her Ph.D. work.