T.H. Shellhammer

• Oregon State University

This study analyzed hops from 35 fields located in two states (Washington and Oregon) repeatedly over 2 harvest years (2020 and 2021) to determine the impact that hop variety and regional identity, or "terroir, " might have on hops' dextrin reducing enzymatic potential. Cascade and Mosaic® hops were harvested, kilned, pelletized, and analyzed for d...

BACKGROUND Regional identity is a well‐established concept of economic interest that has been identified as a source of unique quality traits of various agricultural products originating from a specific region. In the context of hops, the exploration of regional identity is still at a very early stage despite an increasing global demand for special...

Hop drying is an important step during the hop harvest, where hops must be quickly dried from 70–80% to 8–12% moisture to prevent deterioration of hop cones. Collaborating with hop growers in Oregon and Washington, U.S.A., the study employed commercial-scale drying experiments to investigate the impact of drying hops using static 130 °F (54 °C) and...

This presentation examines the regional identity of Cascade and Mosaic® hops grown in 2020 on 39 individual fields throughout the Willamette and Yakima valleys in the Pacific Northwest and explores environmental and technological factors impacting the hop characteristics to better understand and potentially control this effect in the future. Hops...

In Saccharomyces, the IRC7 gene encodes for a cysteine S-conjugate β-lyase enzyme which can release polyfunctional thiols from their cysteinylated precursor forms, thereby promoting thiol aroma in beer. This study examined the thiol production of 10 commercial yeast strains in two different media, a hopped yeast extract-peptone-dextrose (YPD) mediu...

Hops and malt are the two main sources of nitrate in beer, with hops being the primary source in beers that are late-hopped or dry-hopped. A proof-of-concept study was performed to characterize how nitrogen fertilizer dose applied in the field during hop production influences nitrate accumulation in hop-forward beers. To quantify the dose-response...

Kilning represents a substantial energy input for processing hops and has the potential to significantly impact hop quality. As part of a multi-year project to understand how different kilning parameters influence the brewing quality of popular American hop varieties, this study examined how kilning temperature impacts chemical and sensory changes...

Understanding the role barley variety plays in the overall flavor profile of beer is an area of research of interest to barley breeders, maltsters, and brewers. Here we build on previous research on the effect of barley variety on beer flavor by focusing on commercial-type malts and beers. A selection of three winter-habit, elite malting lines – tw...

The biotransformation of hop aroma, particularly by the cysteine S-conjugate beta-lyase enzyme (CSL), has been a recent topic of tremendous interest among brewing scientists and within the brewing community. During a process often referred to as biotransformation, yeast-encoded enzymes convert flavorless precursor molecules found in barley and hops...

The impact of the growing environment on the aroma of agricultural products such as wine, coffee, or tea has been investigated in detail, leading to the concept of regional identity; however, there have been only limited studies examining regional variation in hops. A systematic investigation of Cascade and Mosaic® hops from the 2020 harvest year g...

The characteristic hoppy flavor of pale ales is known to be unstable and deteriorates during the beer's shelf life. Metal ions, in particular iron and copper, have a prooxidative effect and therefore accelerate beer flavor deterioration. Recent studies suggest that hop constituents may complex metal ions in beer thereby suppressing their negative e...

There is an increasing interest in the regional identity of hops and potentially associated quality traits. We hereby present a case study involving Cascade and Mosaic® hops grown in 2020 on 41 individual fields throughout Oregon and Washington. Soil chemistry, microbiome and physical properties as well as climate were assessed by also taking into...

This presentation explores the impact of environmental (soil, climate) and technolocigal factors (field management) on the quality (sensory, chemistry) of Cascade and Mosaic hops grown in 39 field locations by 22 different commercial hop growers in the Willamette Valley, OR, and the Yaikma Valley, WA to define the regional identity or terroir of th...

The influence of growing region on hop quality is examined in three American aroma hop varieties (Mosaic®, Simcoe® and Strata®) from eleven locations throughout the Willamette Valley, OR. Hops from each site were analyzed for total oil content, α- and β-acids, and the oil was analyzed via GC-FID to quantify selected aroma compounds. Single-field IP...

The influence of growing region on hop quality was examined in three American aroma hop varieties (Mosaic®, Simcoe® and Strata®) that were harvested from two to five distinct sites within each of eleven commercial fields located throughout the Willamette Valley, Oregon. Weather, climate, and management data were collected for each of the eleven fie...

To investigate potential sources for field-to-field variation in hop diastatic power, three varieties of hops (Mosaic®, Simcoe®, and Strata®) from harvest year 2019 were collected from different fields managed by a single hop grower throughout the hop growing region within Oregon’s Willamette Valley. Fields for this study were selected based on soi...

Heirloom barley (Hordeum vulgare L.) varieties remain interesting to maltsters and brewers for their perceived unique flavor contributions to beer, despite not meeting contemporary agronomic and malting expectations. This study utilized crosses of the heirloom Maris Otter® and two contemporary genotypes to determine if “updated heirlooms” could be...

In recent years, hop growers worldwide are increasingly interested in determining whether hop characteristics are unique for specific growing regions; that is whether they possess a regional identity or there exists a terroir effect. This study deepened our understanding of regional effects on hop quality via a large collaborative project involving...

Irrigation is essential for hop production in the Pacific Northwestern United States, the primary growing region in the U.S. Irrigation water supplies can be inadequate in drought years and may become more variable in the future due to climate variability and increasing non-agricultural demand. In this research, the impact of delayed timing of the...

Kilning represents a considerable energy input in the production of hops and has a direct impact on hop quality. This study investigates how kilning temperature impacts the dextrin-reducing enzymes in hops in two major aroma cultivars, Amarillo® and Simcoe®, by manipulating kiln temperature on a pilot and commercial-scale. There is evidence that du...

Dry-hop creep is a gradual reduction in beer gravity after dry-hopping in the presence of yeast due to generation of fermentable sugars from nonfermentable dextrins by hop-associated enzymes. A benchtop forced fermentation-based method for estimating the dextrin reducing potential of hops during dry-hopping is proposed and evaluated for feasibility...

Recent research has demonstrated contributions of barley genotype to beer flavor based on the progeny of a cross between an heirloom and a more contemporary barley variety. To advance this line of research, the current study used two independent sets of barley germplasm to address the contributions of different barley genotypes to beer flavor. Pedi...

Hopping rates are on the rise in the US craft beer sector, and highly dry-hopped beers are gaining popularity. Brewers observe that after they dry-hop their beer, there can be a slow production of fermentable sugar, and if the beer still has yeast in it, a corresponding production of alcohol and CO2. This production of alcohol and CO2 can take the...

Previous research demonstrates that barley genetics can influence beer flavor. However, the chemical basis for differences in beer flavor attributed to barley is not well defined. Here, the associations between beer volatile compounds and sensory descriptors were investigated in a controlled experiment, whereby barley genotype was the main driver o...

Dysphania is an abundant genus of plants, many of which are endemic to the Australian continent, occurring primarily in arid and temperate zones. Despite their prevalence, very few investigations into the phytochemistry of native Dysphania have been undertaken. Described herein, is the isolation and elucidation of two enantiomeric diastereomers of...

Multi-stage dry-hopping is a technique that is widely used by brewers to achieve intense hop aroma in beer. However, a thorough analysis of its efficacy does not exist in the published literature. The goal of this study was to compare the properties of beers produced by single or two-stage dry-hopping at the same cumulative rate. On the pilot scale...

As public awareness of anthropogenic climate change grows and consumers demand more sustainably produced products, it is imperative that the beer industry implements more sustainable production processes. Fortunately, there is a growing body of work related to the sustainability implications of beer production, which can help to advise brewers in d...

With the rising popularity of hop-forward American ales, dry-hopping has emerged as a ubiquitous technique for achieving pronounced hop aroma and flavor in beer. Due to the low temperatures at which dry-hopping is carried out (relative to kettle additions), hop-derived bitterness precursors are neither isomerized nor transferred to beer and remain,...

Recently, the enzymatic dextrin reducing power of hops has been identified as a potential safety concern in dry-hopped bottle conditioned beers. During dry-hopping, hop enzymes are extracted into beer and have the ability to breakdown the unfermentable residual beer dextrins into fermentable mono- and di- saccharides (glucose and maltose). In bottl...

Dry-hopping, which is the cold, aqueous extraction of hops into beer, has gained popularity in recent years as a method for achieving intense hop aroma and flavor in beer. With some brewers dry-hopping at rates up to 2 kg/hL ($5 lb/barrel), considerable waste is generated in terms of both beer loss and spent hops. The retention of valuable volatile...

A multi-year field study was conducted in Oregon and Washington to evaluate the influence of nitrogen fertilization rate and timing on cone quality and nitrate accumulation in cones. The impact of nitrogen rate on cone yield, levels of hop acids, total oil content, color, and nitrate level were year dependent. However, when data were aggregated ove...

This study evaluated the impact of kiln temperature on dry-hop aroma potential of Amarillo® and Simcoe® hops across 2 different harvest years. Hops were dried over a range of temperatures (47ᵒC, 60ᵒC, 77ᵒC and 82ᵒC) on pilot scale and commercial scale kilns. The hop storage index increased with kiln temperature, however the concentration of humulon...

Cascade, Chinook, and Centennial are hop varieties with distinct aromatic characteristics of American hops and they are used extensively for dry-hopping singly and/or in blends to impart intense hoppy aroma to beer. A sensory directed dry-hopping mixture study was performed to understand the aroma contribution that each of these hops make to beer a...

It is generally recognized within the brewing industry that hop aroma and flavor in beer changes as beer ages post-packaging. Lager beer staling has been studied extensively, while dry-hopped beer has received limited attention. This study evaluated the impact of dissolved oxygen on the sensory and hop volatile profiles of dry-hopped beer during st...

Enzymes in hops have recently been demonstrated to hydrolyze beer dextrins, produce fermentable sugars in finished beer, and pose significant safety and quality challenges for brewers. In an effort to mitigate beer refermentation following dry-hopping in the presence of yeast and the effect of "hop creep," brewers look to adjust recipes, selection...

Eighty-four individual hop samples were gathered over three harvest years to determine chemical factors in hops that serve as indicators of a hop's aroma potential during dry-hopping. Two public American hop varieties that are important to U.S. hop farmers and used by craft brewers globally, Cascade (n = 51) and Centennial (n = 33), were evaluated....

Recently, the evolution in the production of hop-forward beer styles has brewers reexamining their hop usage throughout the brewing process and is resulting in a coincidental change in the definition of hop quality. The increased use of aroma hop additions and the demand for aroma hop varieties have shifted brewers' focus toward hop oil content and...

The considerations that constitute hop quality have been changing in recent years as brewers use greater and greater quantities of hops for aroma additions to increase aroma perception while striving to keep total bitterness low and consistent. Several analytical drivers of overall hop aroma intensity and quality have been identified in various stu...

The chemical factors that predict a hop lot’s aroma potential during dry-hopping were investigated using 118 individual hop samples gathered over the 2014, 2015, and 2016 harvest years. The goal of this project was to determine if differences in beer dry-hop aroma intensity and quality could be described by variation in total hop oil and/or individ...

Cascade is the main hop variety used by U.S. craft brewers, especially for late and dry-hopping. How harvest maturity impacts the aroma potential and chemistry development of this variety is not well understood. Working with a commercial hop farm in Washington, a unique harvest maturity sampling protocol was performed to evaluate the impact on Casc...

American craft beer styles/flavors are often driven by the unique qualities of American hops. Cascade, Chinook, and Centennial hops are American hop varieties that are prominently used singly or in blends by brewers. Both sensory and chemical techniques were used to probe the unique aroma quality and intensity of these varieties in dry hopped beer....

American craft beer style and flavor is often driven by the unique qualities of American hops. Cascade, Chinook, and Centennial hops are used prominently for dry-hopping singly and/or in blends to impart an intense hoppy aroma to beer. A sensory directed dry-hopping mixture study was performed to understand the contribution that each of these hops...

Hop essential oil analyte specific extraction (into beer) and retention (in spent hops) rates during pilot scale dry-hopping

Cascade, Chinook, and Centennial hops are used extensively throughout the brewing industry either individually or in various combinations to add hoppy aroma to beer. This high use of hops, particularly via late- or dry-hopping, creates a need to better understand the chemical contribution of these hop varieties during dry-hopping beer in order to p...

In the United States, the average usage of aroma hops by brewers has been increasing over the 20th century. This has led to the increased acreage and production of aroma hops. Harvest maturity is one of the main quality drivers of a hop’s aroma potential in beer, however a major pinch-point in commercial hop-harvesting/processing is kilning. This c...

An overview of the extraction efficiency of hop bitter acids and essential oil during pilot scale dry-hopping

Dry‐hopping is a technique that has been used by brewers to increase the hop aroma and flavour of beer for centuries. Throughout the twenty first century, dry‐hopping has become an increasingly popular method among craft brewers to impart intense hoppy aroma and flavour to beer. Many US craft brewers use extremely high dry‐hop dosing rates of up to...

The range of different nonvolatile constituents extracted from hops in highly hopped beers suggests that isohumulones may not be the sole contributor to beers' bitterness. Among brewers producing hop-forward beer styles there is concern that the Bitterness Unit (BU) is no longer an accurate predictor of beer bitterness. This study examined factors...

The impact on analytical and sensory bitterness of hop acids and hop-derived polyphenols resulting from dry-hopping in beer was investigated using a pilot-scale dry-hopping study and a commercial dry-hop survey. The pilot-scale dry-hopping study utilized a trained sensory panel to quantify increases in bitterness caused by dry-hopping an unhopped a...

Little is understood regarding the fate of polyphenols during beer aging. Lager beers were produced with varying hopping regimes to investigate hop product contribution to beer polyphenol and flavanol contents. Finished beers underwent forced aging (30°C) and were monitored for changes in flavan-3-ol profiles. Sephadex LH20 resin was used to produc...

Many factors contribute to the complexity of beer flavor, including odor-active hop oil compounds. Best estimate thresholds of 10 hop compounds were reported in unhopped pale ale beer with ethanol contents of 5 and 10% alcohol by volume (ABV) using ASTM E679 threshold methodology. Although the solvating properties of ethanol had the potential to im...

Dry hopping has been used by brewers to impart hoppy aroma character to beer for centuries and is becoming an increasingly popular method among US craft brewers. Many US craft brewers use extremely high dry hop dosing rates of up to 1000 g/hL and this is both unsustainable and wasteful. This study examined the impact of dry hopping rate on the sens...

Previous studies show that the complexity of hop aroma in beer can be partly attributed to the hydrolysis of glycosidically bound monoterpene alcohols extracted from hops during the brewing process to release volatile aglycones. However, fundamental studies that examine the extraction of glycosides during brewing and their subsequent hydrolysis by...

Recently, brewers have dramatically increased the complexity and intensity of aromas in hop-forward beers by using diverse hopping regimes. For this study, the terpenoid content and sensory attributes of beers made using different hop additions were measured. Beers were brewed while varying two factors: hop cultivar (Simcoe and Hallertau Mittelfrüh...

The essential oil fraction of hops clearly plays a significant and important role in their contribution to the aroma of beer, yet the potential role of water-soluble flavor precursors in hops is much less certain. The study presented herein investigated a range of glycoside hydrolysis techniques on the aqueous extracts of " spent " hops obtained af...

Brewers who create hop-forward styles such as American-style India Pale Ales typically add hops toward the end of or after wort boiling to avoid aroma volatilization and thereby impart strong hop-derived aromas. However, previous studies have demonstrated that despite the volatilization effects of boiling wort, hops that are added early in kettle b...

We observed qualitative changes in the chemical and aroma profile of Hallertau Mittelfrüh (HA) hop pellets after storage under prooxidative conditions. It was hypothesized that lager beer dry-hopped with oxidized HA hops would impact both the qualitative attributes related to "noble" hop aroma in the finished beer and consumer acceptance. Lager bee...

Aliphatic γ- and δ-lactones with 9-12 carbons (y-C9-12 and δ-C10&12) possess rich peach and coconut odors and could be a potential source of fruity, especially stone fruit (i.e., peach and apricot), aroma in beers. To assess the influence of these lactones in a complex beer matrix, low levels (μg/L) of these lactones in combination with oxygenated...

Notable differences exist between American and traditional European hops in terms of the types of flavor they contribute to beer. Brewers tend to describe the former as contributing citrusy, fruity and in some instances floral aromas, while the latter are often described as contributing herbal, tobacco, woody, and spicy notes. Single-hop brewing tr...

Humulinone and hulupone extracts were prepared for evaluating their bitterness intensity in beer. Previously established methods for oxidizing α-and β-Acids followed by preparative liquid chromatography resulted in humulinone and hulupone extracts of 93.5 and 92.7% purity, respectively, as measured by HPLC. The humulinone and hulupone extracts were...

When hops are added to beer, varying degrees of hoppy aroma persist as a result of cultivar differences and the point of hop addition. Dry hopping is a technique whereby hops are added to beer to leverage the maximum aroma potential of the hop oil. Given that hop oil serves as the primary reservoir of aromatic compounds in the hops, we hypothesized...

This handbook showcases a variety of food fermentations ranging from beer and wine to cider, whisky, rum, vinegar, bread, cocoa, tea, and coffee. With authoritative accounts from many experts, it also features a diversity of fermentation products such as dairy products, vegetables, fermented meats and fishery products, and Asian foods. Fermentation...

Considerable expertise is required to grow high-quality hops, and brewers and hop growers alike have a common goal of obtaining the highest quality hops possible. Changes in the chemical composition of hops during plant maturation is a dynamic process requiring a comprehensive chemical and sensory analysis in order to maximize the characteristics o...

J. Am. Soc. Brew. Chem. 72(4):231-238, 2014 Considerable expertise is required to grow high-quality hops, and brewers and hop growers alike have a common goal of obtaining the highest quality hops possible. Changes in the chemical composition of hops during plant maturation is a dynamic process requiring a comprehensive chemical and sensory analysi...

Beer is one of the most commonly consumed beverages world-wide and it is nearly always brewed with hops (Humulus lupulus, L.). Although hops contribute a mere fraction of the beer raw ingredient bill, the use of hops immensely impacts the flavor and quality of finished beer. Hops can provide beer with bitterness, aroma, flavor and texture and also...

Table of content Preface Analytical 1. Spice Up Your Life: Analysis of Key Aroma Compounds in Shiraz M. J. Herderich, T. E. Siebert, M. Parker, D. L. Capone, D. W. Jeffery, P. Osidacz, and I. L. Francis 2. Analytical Investigations of Wine Odorant 3-Mercaptohexan-1-ol and Its Precursors Dimitra L. Capone, Mark A. Sefton, and David W. Jeffery 3. Str...

Aroma is one of the most important quality attributes for wine and many other alcoholic beverages. However, the chemical composition of most alcoholic beverages is so complex that it has always been a challenge for scientists to fully understand their flavor chemistry. The low concentration of key aroma compounds, such as thiols, the low sensory th...

Minnesota under the guidance of Dr. Gary Reineccius. Dr. Qian's research interests at Oregon State University focus on flavor chemistry and instrumental analysis involving solventless sample preparation such as solid phase micro-extraction, solid phase dynamic extraction, stir bar sorptive extraction, and fast GC, multi-dimensional GC/GC-MS analysi...

The rate of hop aroma compounds extracted from Cascade hops during dry hopping was studied using a model beer system devoid of malt, yeast aromas, and hops. Cascade hops pelletized by four different processors yielded different particle size distributions and pellet densities. These pellets were dosed into a degassed medium (water, 6% v/v ethanol,...

Metal chelation and scavenging of highly reactive hydroxyl radicals are commonly proposed to explain the antioxidant behavior of hop acids. In the current study, an assay measuring the oxidative degradation of 2-deoxyribose (2-DR) by hydroxyl radicals was used to elucidate these mechanisms and examine the origin of the ability of hop acids to preve...

The bitterness of four hop-derived compounds was measured over a range of concentrations using a time–intensity protocol to determine temporal bitterness relationships. Bitter attributes were compared among compounds by applying a three parameter, change-point model to all concentration-dependent attributes whereby α represented the bitter paramete...

J. Inst. Brew. 116(4), 369–380, 2010 Generally referred to as polyphenols (PPs), beer flavonoids such as the flavan-3-ols and their condensed products, the proantho-cyanidins, represent a class of readily oxidizable compounds capable of hindering or preventing the oxidation of other mole-cules present in beer. Flavan-3-ol and proanthocyanidin capac...

J. Inst. Brew. 116(2), 157–166, 2010 The oxidative stability of wort at different stages during wort production and the radical scavenging characteristics of α-, β-, iso-α-acids and a hop polyphenol extract were evaluated using ESR spectroscopy and DPPH • radical quenching measurements. Radical generation in unhopped wort was significantly, posi-ti...

Beer quality can be defined in many ways. Combining consumer liking data and trained panel sensory descriptive data, this presentation will present a case study whereby the importance of hops on beer quality is demonstrated. Hop-related descriptive attributes such as "grapefruit" and "piney" aromas as well as bitterness intensity were positively co...

The measurement of yeast's intracellular pH (ICP) is a proven method for determining yeast vitality. Vitality describes the condition or health of viable cells as opposed to viability, which defines living versus dead cells. In contrast to fluorescence photometric measurements, which show only average ICP values of a population, flow cytometry allo...

Foam-stabilizing properties and cling formation patterns of iso-alpha-acids and reduced iso-alpha-acids were investigated using an unhopped lager beer. Unhopped beer was dosed with iso-alpha-acid (Iso), rho-iso-alpha-acid (Rho), tetrahydro-iso-alpha-acid (Tetra), and hexahydro-iso-alpha-acid (Hexa), separately, over a range of concentrations from 2...

The visual quality of beer depends on color, clarity and foam characteristics and how these support or negate consumer expectations regarding the particular style and brand. Beer color originates principally with Maillard reaction products formed during malting within the. grain used to prepare the wort for fermentation. Kilning malted barley creat...

A polyphenolic extract was produced from spent Galena hop material and added to a low-bitterness, commercial lager beer at three levels (+0, +100, and +200 mg/L) along with iso-alpha-acids from a preisomerized Galena hop extract at two levels (+0 and +10 mg/L) to examine the impact on bitterness character by time-intensity (TI) and free-choice prof...

The relative bitterness of reduced and nonreduced iso-α-acids in lager beer was measured using a time-intensity protocol in which a trained panel evaluated seven concentrations of each compound in an unhopped lager beer. The peak intensities were measured, and within each panelist, a nonlinear dose-response curve was fit to the data. Equal-bitter r...

Corn tortillas have a short shelf life due to increased firmness and microbial spoilage. Commercial corn tortillas use carboxymethyl cellulose (CMC) to delay staling; however this gum is expensive when compared to the rest of the tortilla ingredients. Glycerol has been added to bread and wheat tortillas to increase pliability and salt has been show...

The temporal and qualitative bitterness of reduced and nonreduced iso-α-acids were measured in this study. A trained panel using a time-intensity protocol determined the temporal attributes of these compounds added to an unhopped lager beer. Principal components analysis and analysis of variance were applied at equibitter concentrations to determin...