View Article

MBAA TQ vol. 56, no. 4 • 2019 • pp. 141–148 PEER-REVIEWED SUBMISSION First Steps Toward Understanding the Regional Identity of Hops Grown in the Willamette Valley, Oregon Elizabeth Verhoeven,1 Liz Coleman,2 Garrett Weaver,2 Shaun Townsend,1 Andy Gallagher,3 and Thomas H. Shellhammer1 1. Oregon State University, Corvallis, OR, U.S.A. 2. Coleman Agriculture, St. Paul, OR, U.S.A. 3. Red Hill Soils, Corvallis, OR, U.S.A. ABSTRACT Regional identity, or terroir, is the concept whereby the unique flavor ferences among the sites. The hops harvested from each site were ex- and quality characteristics of different crops or products relate to their amined via ASBC standard methods for hop acids, total oil, and oil place of origin, and it is well-studied in winemaking. This study pre- composition. The same hops were used in brewing trials, and the re- sents preliminary evidence of regional differences in two hop culti- sulting beers were subjected to sensory analysis by a panel of profes- vars, Centennial (two locations) and Sterling (three locations), that sional brewers and hop growers as well as a panel of trained sensory were managed similarly in the Willamette Valley during 2018 via a assessors. Differences were observed in soil and local weather char- collaborative effort among Oregon State University (OSU) (Corvallis acteristics, plus chemistry and sensory qualities of both the hops and campus and Marion County Extension), the Indie Hops-OSU Aroma the resultant beers. These results point to the potentially important Hop Breeding Program, Coleman Agriculture, and Red Hill Soils. effects of soil and weather on hop characteristics and open the door Soil chemistry and morphology, local weather data during the grow- to a broader discussion and further inquiry of the regional distinctive- ing season, and regional climate data were gathered to quantify dif- ness of hops. The Concepts of Regional Identity and/or in developed countries increasingly have access to products from around the world and are eager to explore, understand, and de- Terroir as They Apply to Hops velop their tastes for products coming from specific regions. Key to regional identity is the concept that unique flavor and In this same vein, brewers and hop producers are interested quality characteristics of different crops or products relate to in knowing how different production regions and practices in- their place of origin. These unique characteristics may result fluence hop cone chemistry and aroma profiles. In the produc- from differences in climate, geology, soil, local management tion of beer, hops not only provide bittering and preservative practices, or processing practices. In this regard, regional iden- qualities to beer but also flavoring and aroma components. The tity is very similar to, and perhaps is synonymous with, the con- production and use of aroma hops have risen steadily, driven by cept of terroir. The wine industry has a long history of utilizing craft brewing demand (8). This increase in aroma hop use has the terroir concept to help characterize and classify different potentially opened up new opportunities for regional differenti- wines, to identify current and future production regions, and for ation and identity. The overarching question is, can hop quality product marketing. The creation of American Viticultural Areas such as chemical profile, flavor properties, and aroma proper- was based in large part on the premise that regional differences ties be related to specific sites, and if so, what site properties are in wine grapes exist, and these differences are perceivable by important? Although evidence linking hop aroma chemistry to winemakers and consumers. Beyond wine, other examples of re- production regions is limited, three recent studies conducted on gional identity can be found in a wide variety of food products a global scale have begun to address this question (2,16,20). such as cheese, fruit, coffee, and olive oil (3,22). Indeed, consum- The exact variables measured to delineate a region or define ers, producers, and buyers have long held preferences for prod- terroir are not standardized; however, they generally include ucts coming from certain regions. This has grown as consumers measures of climate, geology, geomorphology, and soil type (5,21,22). The set of variables should reflect attributes known to influence the final product (for instance, timing of fruit maturation, ratio of acid to sugar, and concentrations of specific E-mail: [email protected] aroma or flavor compounds). For many products, we do not know the precise variables or the interactions among them that https://doi.org/10.1094/TQ-56-4-1215-01 influence the end product. A suite of variables considered im- © 2019 Master Brewers Association of the Americas portant for defining wine grape terroir can provide us with a 141 142 MBAA TQ vol. 56, no. 4 • 2019 Regional Identity of Hops starting point, but one should remember that hops are a very at the farm or field level, for example, climate factors become different crop, so the same variables may not be as useful for less important relative to soil properties and drainage. defining hop terroir. There is growing evidence that regional differences in hop Aroma hop production targeting the craft beer industry is still chemistry and consumer-detectable aroma hop characteristics a relatively new endeavor, and little data exist describing best may exist, at least at the national and global levels. However, management practices for influencing hop aroma (besides cul- we cannot yet tease out specific climate effects among regions tivar choice). However, to begin thinking about the most influ- or years if they exist, nor do we understand the impact soil var- ential variables of hop quality, we looked at the most studied iation and management practices might have. Studying these production aspects—irrigation, growing season temperature, and factors at the farm level may provide insight into the effect that harvest timing—and also looked at additional variables that are these variables might have and guide management decisions for used to describe wine terroir. On a global scale, we also know high-quality aroma hop production. that latitude plays a strong role in hop development because the The study described herein examined two American hop va- initiation of flowering is day length sensitive, and most hop cul- rieties, Sterling and Centennial, grown at three different loca- tivars need sufficient chilling during dormant months for opti- tions within the Willamette Valley. The work began at the re- mal regrowth. For these reasons, hop production has historically quest of Coleman Agriculture, Oregon’s largest hop producer occurred between 30 and 52 latitude N or S (7,14). Some studies and one with over 120 years of continual hop growing experi- have shown no effect of irrigation on -acid and -acid contents ence. Aware of consumer interest in regional identity, its use in (6,13). However, Srečec et al. (19) did find a negative correla- the wine industry, and growing interest among hop buyers and tion between evapotranspiration (an indicator of water and/or brewers, Coleman Agriculture wanted to better understand their heat stress) and hop cone yield and -acid content. In general, own farm sites and gain insight into what variables might affect it is difficult to decouple heat and moisture stress in these stud- hop quality at the farm level. They wanted to characterize the ies. Air temperature can affect bine maturation. High air tem- soil variability among farm locations and within a field to help peratures during cone development, particularly during the third guide management decisions. This work has begun a longer to fourth week of flowering, might be most critical. Srečec et al. journey toward understanding and characterizing regional dif- (18) found that the onset of bloom and the time between sec- ferences of hops grown in the Willamette Valley, Oregon. ondary branching and flowering affected both yield and -acid content. They found that increased heat units negatively affected Methodological Approach to Assessing cone yield and accumulation of -acid. In a drought year, yield was halved from 1,800 to 900 kg/ha, and -acids decreased Regional Identity for Centennial and Sterling from 11.5 to 6.2%. Similar patterns were observed over a 6-year Grown in 2018 period in other work (19). The authors emphasize that temperature, heat units, and rainfall are most critical during cone devel- Identification, Description, and Characterization of opment (July to August in the United States). Locations within Coleman Agriculture Farms Three recent studies show that hop essential oils are sensitive Coleman Agriculture is the largest hop grower in Oregon and to harvest timing (10,11,17). In each study, hop oil content in- produces hops in three distinct regions within the Willamette creased with a delay in harvest. Lafontaine et al. (10) noted that Valley: St. Paul/Gervais, Mt. Angel, and Independence (Fig. 1). this increase in oil content was associated with increased aroma One Sterling and one Centennial field at each of these locations intensity and citrus quality in Cascade hops. Their analysis of was studied with cones harvested in 2018. sensory attributes also showed that samples from a given year Homeplace Farm (St. Paul and Gervais, OR). The Home- tended to clump together, suggesting that unique aroma chem- place farm consists of disconnected plots scattered around St. istry developed in a given year. Hop acid content may be less Paul and Gervais, OR, totaling about 900 acres (364 ha). This sensitive to harvest timing than essential oil content (12,17). agricultural area is where most Willamette Valley hop producers Aside from the variables used to define terroir, the scale at are found. The two fields observed for the study are 8 miles (13 which terroir is defined can vary.

Load more