Due to the number of exceptional craft breweries in our region, farmers continue to plant acres of hops. Over the past several seasons, hop growers have become frustrated and brewers disappointed as hop yards are harvested too early. More often than ever, brewers and their consumers value aromatics over bittering flavors. We know that the bitter hop resins develop before aromatic qualities in hop cones. Northeastern growers are currently harvesting for bittering attributes of hops rather than waiting for aromatic essential oils to develop. Hop harvest dates developed for other production regions are not appropriately timed for our climate.
The focus of this research project was to gain a better understanding of when hops should be harvested to determine when aromatic essential oils may peak.
Many of the samples submitted for analysis in 2018 could not be analyzed by the analytic company. The results of the samples sent in 2018 did not allow for any definitive conclusions to be derived.
The results derived from the 2019 samples prove that the sampling methodology is sound and demonstrated some promise in that one can predict the optimal time to harvest hops. Yet, since there is only one set of data, more research is required to assist in being able to predict hop harvest. This project only looked at hop harvesting time for Cascade hops. Yet other commercially valuable varieties could be studied as well.
Since only one year of reliable data has been collected, one cannot derive any conclusions on how harvest timing impacts essential oils levels in harvested hops. More, long-term, research is necessary to study what impact harvest timing has on essential oil levels. Especially, to take into consideration what impact, if any, cultural practices during the growing season influence influences (or not) acid and essential oil levels.
Our overarching goal is to improve the quality of hops grown by local farms and bought by local brewers.
Objective 1. Identify and quantify when resin and essential oil compounds develop in Cascade hop cones. Indications of success will include closely matched oil levels to those of other regions, fully developed citrus aroma, and satisfied brewers.
Objective 2. Understand which compounds and the quantity of each that local brewers look for in a lab report when making hop purchase decisions. If successful, growers will know which compounds and what level of each is considered high quality in our region.
Objective 3. Educate growers by disseminating our findings at 3 grower-brewer sensory evaluation events (2 in NY, 1 in VT), 2 annual hop conferences, 2 recorded webinars, and outreach materials printed for events and posted on the UVM Northwest Crops and Soils (NWCS) and Northeast Hops Alliance (NEHA) websites. Pre and post “quizzes” will indicate knowledge learned over the course of this project.
Hop cones form in late July and develop until they are harvested in late August through the end of September. Inside the cone, there are modified trichomes (leaf hairs) called lupulin glands. As the cone develops these glands start to fill with chemical compounds which include both resins (alpha and beta acids) and essential oils (Oliveira and Pais 1988). European work conducted in the 1980s, indicated that resins develop in the hop cone first, followed by essential oils. If a brewer is looking for more aromatic qualities in their final product, they will select a hop that has matured longer on the bine (Sharpe and Laws 1981). Now more than ever, brewers in the northeast value essential oils to create “citrusy” and “juicy” IPAs that are flying off the shelves. Specifically, New England brewers have received praise for their new style of aromatic beer which is now nationally recognized. Called a “New England IPA,” they have established a new style of beer (BB Magazine 2017). If local hop growers are currently harvesting when resins have developed but essential oils have not, how can they meet the demands of local brewers who require the aromatic qualities of essential oils?
Several studies conducted by the project leaders have contributed to the re-emergence of the northeast hop industry over the past six years. While hop harvest quality has been measured throughout these pest management framed projects (NESARE GNE12-033, NE IPM 027269), essential oil levels were not collected. The resin data collected was one snapshot in time when hops were harvested. The ongoing NESARE hop nutrient and pest management project (LNE16-348) does not include a study of hop harvest timing. Steve Miller, NY Hop Specialist, has worked with Rich Michaels, head brewer at Saranac Brewing, to compare chemical profiles of hops grown in NY state to those bought in from the PNW. This work has shed light on the variability and potential high quality of hops grown in the northeast (Cornell Hop Conference 2016). However, this work has been a survey of hop quality on many farms rather than a scientific assessment of when compounds develops here. Farmers require replicated readings of hop resin and essential oils from more than one growing season to be able to identify when their hops are ready to harvest. Furthermore, Extension specialists in at least 12 states nation-wide are conducting hop variety trials. To our knowledge, through our participation on the NCIPM Great Lake Hop Working Group, these programs have not identified regionalized hop harvest dates that highlight the best qualities of their hops based on local environmental factors and brewer input.
Hop harvest timing depends on multiple on-farm factors such as disease and insect pressure, irrigation, fertility, soil type, and canopy humidity. In the PNW, date ranges have been developed for specific regions and even individual farms (Crosby Hop Farm, personal comm.). Here in the northeast, smaller growers cannot afford to ship several samples overnight to Yakima, WA for analysis before harvest, nor can they afford their own on-farm labs. Therefore, they rely on hop cone moisture content in conjunction with sensory observations to determine when to harvest. Moisture content varies dramatically depending on relative humidity and farm management practices throughout the season. Visual and olfactory clues are helpful, but subtle and difficult for our untrained senses to pick up.
We have modeled this project after hop harvest timing work conducted by Oregon State University. Sharp et al. 2014 measured hop chemistry development in cones collected from two farms located in the Willamette Valley, Oregon. By measuring resins and essential oils at three-time points during cone maturation, the researchers were able to show that resins remained unchanged through maturation while essential oils significantly increased over the course of their 3 week sampling period in the field. Importantly, this study used brewers’ sensory evaluation in addition to lab reports to understand which compound levels produced the desired aroma in the end product (Sharp et al. 2014). Our project will similarly take several chemical profile readings as hops mature in the field. We hope to educate both growers and brewers on the environmental factors that influence hop chemistry development and the use of essential oil analysis as a harvest determination tool.
- - Producer
- - Producer
- - Producer
- (Educator and Researcher)
Cascade hops from three northeastern farms were collected and analyzed in 2018. The three farms who have agreed to be a part of this project are Borderview Farm in Alburgh, VT (latitude: 44.9°N, 73.3°W), Cold Spring Hops in Granville, NY (latitude: 43.4°N, 73.2°W), and Kinderhook Creek Hop Yard in Chatham, NY. Each farmer will manage their hop yard according to their standard growing practices.
Each farm received a visit in May or June to identify hop bines that would be used for the research trial. Steve and Heather remained in communication with the hop growers to learn when they estimated they would start harvesting. A sample was collected one week prior to their estimated harvest date. A sample was collected when they harvested the Cascade hops. The identified bines were left uncut and sampled one week after the hop producers harvested their hops.
Each sample will be 150g of wet hop cones were shipped to Alliance Analytical Laboratories (AAL), 179 Randall Street, Coopersville, MI 49404, overnight.
In addition to these shipped samples, Steve and Heather dried and processed one Cascade hop sample (1 kg) from each collection date from each farm for the sensory evaluation events using a food dehydrator and vacuum sealer. These samples were dried, labeled, and stored in a freezer.
There were some issues with the samples collected in both states. AAL did not receive an adequate sample size of some hops from some of the NY farms for analysis. Some of the VT samples molded while at the AAL. In NY, composite samples were prepared for blind sensory analysis activity. Laboratory analysis results for some of the NY samples were received and printed for the sensory analysis.
At the 2019 10th Annual UVM Hop Conference two sessions were held regarding hop quality and the need for consistent standards for harvest to fully develop hop aromas and flavor profiles. From this conference survey, 88% of growers stated that they would benefit from additional information regarding harvest timing, and growers stated that they would “much appreciate for UVM to explore sensory analysis/evaluation” for hop quality.
Despite lab difficulties in the 2018 growing season where samples molded before essential oil composition analysis, UVM was able to compile a report geared towards growers and industry professionals for the harvest timing experiment (attached).
During the 2019 growing season the experiment continued as planned for a second year and hop samples were collected during the proposed three harvest windows. These samples again included an “Early,” “Normal,” and “Late” harvest period for the hop yard at Borderview Farm in Alburgh, VT. Samples were collected and sent to Cornell Agritech in Geneva, NY to be processed for brew quality and essential oil profiles. University of Vermont data for this project is currently being analyzed and will be compiled for an additional report for the 2019 growing season that will be made widely available to growers and industry professionals to aid and assist future decision making on hop harvest.
One farm dropped out and Rockin Hops was added. Communication took place with each cooperator to inform/remind them of the procedure of identifying hop bines for the research project. The same harvesting sequence was used again this year. These samples again included an “Early,” “Normal,” and “Late” harvest period for each hop yard. Samples were collected and sent to Cornell Agritech in Geneva, NY to be processed for brew quality and essential oil profiles.
Results were received and reviewed to see what, if any, conclusions could be obtained. Extension Associate Kaylyn Kirkpatrick was consulted for assistance in analyze the findings of the test results. A sensory workshop was held once again this year at Emporium Farm Brewery. Brewers and hop producers attended the workshop. Those there first conducted a sensory test of the samples and then selected test results were shared.
Due to not having enough samples analyzed in 2018, we will wait for more sampling to share any quantitative results.
For the sensory portions of this experiment, UVM was able to conduct two workshops in 2020 for beers brewed with the hops from our harvest timing experiment. From this experiment, UVM Extension NWCS team was able to develop stronger relationships with local brewers and growers while providing educational opportunities to growers, service providers, and UVM student interns. This was done through our presentations at our 11th Annual Hops Conference and Sensory Evaluation Workshop held at Switchback Brewery.
The first involved a sensory evaluation workshop held at Switchback Brewery in Burlington, VT for to train industry professionals while evaluating beers brewed with the experiment hops. At this workshop UVM’s sensory practice leader Roy Desrochers trained individuals on sensory practice methods and introduced members of Switchback’s existing tasting panel to new terminology and methods for describing beer using industry standards while establishing baselines for comparisons of hop and beer characteristics. With this baseline information, we were able to taste the individual beers brewed with the harvest timing experiment hops and evaluate them using Profile Attribute Analysis (PAA) to generate qualitative and quantitative data. This information was later shared with individuals participating at the Switchback workshop and was followed by a discussion of overall liking of the individual beers. Results from this workshop made it clear that there were distinguishable characteristics that could be parsed out from the beers brewed with different harvest date hops, and overall liking decreased with the latest harvested hops.
Results from the tasting at Switchback were presented at UVM’s 11th Annual Hops Conference held in Burlington, VT on February 28th, 2020 by Ellen Dillenbeck and Stina Stickmueller followed by a second part sensory session conducted once again by Roy Desrochers to include and train attendees in sensory evaluation of beers brewed with the harvest timing experiment hops in an effort to elaborate on common industry methods for analysis to growers and service providers.
Between the workshops at Switchback and UVM Hop Conference, 64 individuals were able to analyze the harvest timing beers and provide an overall rating for them. As a result of the workshops, it was clear that consumers had the ability to detect differences in the beers brewed with the three distinct harvest dates. The last harvest date had the most pronounced “hop intensity” with most intense “cheesy” character. Hops harvested from later dates were noticeably browner in color while also appearing to be less desirable to consumers, and would potentially be less marketable as a result.
In consultation with Kaylyn Kirkpatrick, focused on these factors in the test results Alpha Acids, Total Oils, Myrcene and Nerol. The expected trends were found with Kinderhook Creek samples. Rockin Hops results were not as clear. During the sensory tests at the brewery, participants were able to assess subtle differences between the two hop yar samples.
The results of the samples sent in 2018 did not allow for any definitive conclusions to be derived. A report was prepared by Heather Darby though on what did transpire in 2018. 2018 Hop Harvest Timing Bulletin
In 2019, hop samples were sent to Cornell Agritech for analysis. Below is a summary of what was learned from the analyses.
Here is the hop harvest timing report from UVM. 2019 Hop Harvest Timing Bulletin
The results derived from the 2019 samples prove that the sampling methodology is sound. It is unfortunate that the 2018 samples were not satisfactorily analyzed.
The 2019 analysis of the test results demonstrated some promise in that one can predict the optimal time to harvest hops. Yet, since there is only one set of data, more research is required to assist in being able to predict hop harvest. This project only looked at hop harvesting time for Cascade hops. Yet there are other commercially valuable varieties that could be studied as well.
Education & Outreach Activities and Participation Summary
VT – 2018
A factsheet was prepared in 2018 2018 Hop Harvest Timing
At the 11th Annual UVM Hop Conference, an in-depth sensory workshop took place describing various sensory analytic components in relation to hop cone maturity and the ongoing harvest timing project using these harvest timing hop brewed beers. The sensory session at the 2020 Hop Conference picks up where the last sensory session, led by Roy Desrochers, left off in 2018. During the first 30 minutes, Mr. Desrochers used a PowerPoint presentation to provide a quick review of the basics of objective descriptive sensory analysis including basic tastes, aromatics, and mouthfeels.
NY – 2018
One meeting was set up at Emporium Farm Brewery to bring hop producers and brewers together to review the analyses and to perform a sensory evaluation. Brewery Extension Associate Kaylyn Kirkpatrick attended the meeting to guide participants through the understanding of the analysis results and to coach what to look for in the sensory analysis. After all of the participants had a chance to complete the sensory evaluation, Kaylyn and Steve Hadcock lead a discussion on what the participants felt about the process.
A meeting was set up again at Emporium Farm Brewery to bring hop producers and brewers together to review the analyses and to perform a sensory evaluation. After all of the participants had a chance to complete the sensory evaluation, Kaylyn and Steve Hadcock lead a discussion on what the participants felt about the process.
One farmer reported that they feel they have a better understanding of the importance of harvesting hops in a timely manner. They also reported that they now feel more confident on how to know when it is the best time to harvest their hops.l
As a result of the webinar, do you feel better prepared to harvest your hops on time? 100% (13/13)
As a result of what you learned, will you make a change in your current hop yard? 69% (9/13)
August 2018- Pest and disease scouting, harvest timing
As a result of this goScout:
29% of growers planned on adjusting their harvest timing.
29% of growers planned on adjusting their pesticide applications.
42% of growers planned on making no change.
As a result of participating in this grant, have developed a working relationship with Roger Savoy at Emporium Farm Brewery. Have also developed a working relationship with Kaylyn Kirkpatrick. Kaylyn is Brewing Extension Associate, located in Geneva, NY. Prior to her departure from Cornell Agri-Tech, Kaylyn provided guidance in interpreting the 2019 analysis results.
Some of the samples could not be analyzed, due to not enough hop being submitted. Will revise the method used to process the sample for analysis next year.
Will send samples to the Cornell Agritech next year for analysis. This will reduce the shipping time, which will allow the samples to arrive a little fresher.
Since only one year of reliable data has been collected, one cannot derive any conclusions on how harvest timing impacts essential oils levels in harvested hops. More, long-term, research is necessary to study what impact harvest timing has on essential oil levels.
Hop harvest timing was based upon hop maturity and then analysis took place. In another research project, cultural practices should be logged as well. To determine if how the hops are cared for during the growing season influences (or not) acid and essential oil levels.