Here at DCBeer, and in the brewing community as a whole, we’ve been hearing more and more about how important quality beer is to the long-term success of a brewery. A brewer will employ quality control measures throughout the brewing process. These include water testing, microbial analysis, and examining yeast health pre- and post-fermentation. When brewers use hops, however, they must rely on measurements that the hop grower provides and adjust the recipe accordingly. The reason for the adjustment is that not all hops are the same; hops are an agricultural product, after all. There are differences between varieties, of course, but there is also variation within the same varietal.

YCH HOPS is unquestionably the largest hop producer in the U.S. Back in 2006, two of the largest hop growers, Yakima Chief and Hopunion, formalized a relationship whereby Hopunion focused on the craft segment of the hop market and Yakima Chief on larger breweries. However, by 2014 it was clear that the craft segment was robust enough to support a larger operation, and the companies fully merged.

When I saw a blog post related to YCH’s quality control measures, I had to learn more. I’ve engaged in a fair amount of quality assurance and quality control efforts on the brewing side of things, but my knowledge of how hop growers perform their own quality control was limited at best. So, I reached out to the QC folks at YCH, and their Quality Control Manager, Missy Raver, was kind enough to answer some questions we had related to what sorts of quality control measures they perform and why. Note that there is some pretty technical information here from Missy. I included some explanations where I thought it would help our readers.

1) First, if you don’t mind, can you tell me a bit about you and your background? How did you wind up at YCH?

I started at Yakima Chief in August of 2000 as a laboratory technician right out of college. After a few years, I was promoted to supervisor and then lab manager. In 2006, I left Yakima Chief to work for another hop company and then returned in 2008 as the Quality Control Manager. In addition to managing lab operations, I’ve been active in our ISO 9001 and ISO 14001 programs, safety committee, and answering customer audits and questions.


[ISO is a quality management certification. The number 9001 refers to Standard 9001 that relates to organizational processes pn company efficiency through eight separate factors. Standard 14001 relates to how the company affects the environment.]

In 2014, Yakima Chief and Hopunion combined operations and formed the new company, Yakima Chief-Hopunion (YCH HOPS). With the new company, I became manager of the lab located in Yakima in addition to still managing the lab in Sunnyside. We just recently combined lab operations in Sunnyside and expanded our lab facilities. Our lab now has a supervisor, research technician, and three full-time laboratory technicians. During harvest, we’ll bring in two additional technicians which will stay through the production season.

2) Is analysis done in the field, at harvest, and in a lab? Is the majority of work performed in a lab setting or are you performing analysis all across the board?

The growers do some fertility testing in the field and QC checks for off type varieties and male hop plants. Male plants are removed from the fields to reduce seed development chances in the cone; off types are also removed to ensure pure varietal lots at harvest.

As harvest approaches, growers will hand pick cone samples and bring to the lab for dry matter and/or brewing value analysis. Dry matter analysis tells the grower how much moisture is in the cone and conversely, how much dry matter. This is a measure of ripeness of the cone and when it’s ready to be picked. Brewing value analysis is done by drying the cones down to 8% moisture and then analyzing by UV spectrophotometry to determine the alpha, beta and Hop Storage Index (HSI).

[The HSI will calculate how well a hop will age if kept at a constant 68 degrees for six months. The UV spectrophotometer reading measures the amount of alpha and beta acid levels of the hop. There are also other measures of hop deterioration such as light exposure and improper storage temperature.]

At harvest, samples are taken as hops are delivered to the warehouse at a rate of 10% of the delivery. Also, the warehouse crew QC’s the bales for moisture and temperature. If bales are too wet or too dry or if the temperature is too low, those bales go back to the farm. The samples are taken to the lab for analysis for alpha, beta, HSI and total oil and oil components. Brewers’ cuts are also taken from each lot of hops and go through YCH’s sensory program.

[A “brewer’s cut” is just a section of the bale that is removed for YCH and visiting brewers to analyse from a sensory point of view.]

3) I’ll go out on a limb here and assume a large part of your work is measuring alpha and overall total oil levels – is this just to ensure quality or is there another purpose? By what means is analysis performed?

Yes, most of our analysis is for alpha. We analyze for alpha at harvest, pelleting, and extraction. Leaf hops at harvest are analyzed by UV spectrophotometry for alpha, beta and HSI. HSI is an important measurement as it indicates if the alpha acids has oxidized during harvest. The higher the HSI, the more oxidized the hops are and the faster the quality degrades. This is an especially important measurement for the CTZ varieties, which oxidize at a high rate. CTZ are mostly purchased for the production of CO2 hop extract, which is sold based on the final alpha acid content. So if the alpha degrades quickly, the value of the final product drops dramatically. For this reason all CTZ and other hops with higher HSI’s are immediately pelleted. Once pelleted and packaged in oxygen free foils, the alpha degradation slows; preserving the quality until extracted or shipped to customers.

[The CTZ varieties are Columbus, Tomahawk, and Zeus. These are all high alpha acid hops that are used in pale ales, IPAs, and double IPAs. YCH has a great discussion of the three varieties here: Essentially, Columbus and Tomahawks are of the same genetic makeup, and Zeus is so similar the three hops can be interchanged.]

We also analyze every lot of hops for total oil by distillation and then for the oil components by Gas Chromatography. Other analysis done are alpha, beta, cohumulone and colupulone by HPLC and alpha acids by titration (EBC 7.5 or EBC 7.4). The analyses done are determined by the final customer requirement and all methods follow the ASBC or EBC standard methods.

[Gas chromatography is a technique for analyzing volatile substances in a gaseous state. Also the ASBC is the American Society of Brewing Chemists and EBC is the European Brewing Convention. Ever heard of SRM to gauge color? That’s thanks to EBC.]

4) What happens if the oil levels aren’t where they are supposed to be?


Oil levels vary with each harvest and we have ranges identified for each variety based on historical averages. However, lots do come in lower than the expected range. Typically, we see this when there’s a very hot summer; hops are picked early or picked late. We can’t do much about the weather, but we can provide data back to the grower, so they know if the oil levels of their hops are out of the expected range for that variety. We provide each grower with all the analysis results of their lots and do a comparative analysis of how their lots compare to the average of all the other growers. We review this data with each grower with the goal of providing them with as much data as possible to aid in their harvest decisions.

Lots with lower oils can still have great aroma. We work hard to preserve that great aroma by getting the hops processed and in an oxygen free package as quickly as possible.

5) The same strain of hop can be grown in Washington, Michigan, and New York. Can you tell whether the same hop is comes from a different region? IE, How does growing region affect the end product?

Hops from different regions do have different characteristics, but it’s hard to say if it’s due to a regional difference or due to different growing practices. We also see differences in the analytical data within the same variety but different growers in each region.

6) Are you folks in the lab involved in R&D very much? Is there much opportunity to do any?

Yes, we do some R&D; previously it’s been mostly in the form of developing new products are refining current products. We recently purchased an additional GC/MSD so we can do more R&D on hop oil components. We’re looking forward to using it this harvest.

[“GC/MSD” refers to gas chromatography and mass spectrometry (as mentioned above).]

Of course, I cannot thank Missy Raver from YCH Hops for taking a little bit of time to answer our questions. She is great in every way.