Stan Hieronymus Hop Queries - October 2022 October 2022

Each month respected beer writer Stan Hieronymus produces Hop Queries, a must-read summary of what is happening in the hop world, and has kindly offered to let us publish it for Australian industry readers. If you would like to subscribe directly, you can here.

October 2022

Welcome to Vol. 6, No. 6. I was a bit surprised by how many of you replied you would like to read a recap of information about hop terroir previously reported here. So here’s the plan. Look for it in a shorter form in the November or December newsletter with a link to more details online. That way we will all have a living document to which I may add results of ongoing research. As this month’s featured topic, first word hopping, illustrates, there is seldom a final word when it comes to hop knowledge.

Freshness & dry hop quality

Researchers in Slovenia recently reported on the impact of the freshness of three hop varieties on dry-hopped beer quality. Not surprisingly, they found that using fresher hops resulted in higher quality beer. As well as reminding brewers that it is important to pay attention to the hop storage index (HSI) of every lot, the study further confirms “conventional wisdom” about acceptable and unacceptable levels of HSI.

Quick background: the equation for the hop storage index was developed more than 40 years ago to estimate the loss of alpha-acids and beta-acids during storage. HSI will increase as hops age. At the time, many growers kept bales on their farms longer than today and were less likely to store them cold. Hops were much more likely to degrade quickly, and some varieties, such as Centennial, are particularly vulnerable. Although lower may always be better, hops with an HSI below .3 are considered good quality, between .3 and .4 acceptable and above .4 questionable. Those are very general guidelines.

The Slovenian study (download it here) is noteworthy because the researchers measured the impact on essential oil as well as bitterness, and a sensory panel evaluated the intensity and quality of both bitterness and aroma.

They examined three aroma varieties with five different HSI values, between .3 and .7. Those were Celia, a hybrid of Styrian/Savinjski Golding that many breweries use as a replacement for Styrian Golding, Aurora, and Styrian Wolf, which is well suited for use in hop-forward beers. The beers were dry hopped after seven days of fermentation with 10g/L (comparable to 2.6 pounds per barrel) for five days.

The main takeaways are that the difference between beers dry hopped with varieties with an HSI of .3 and .4 may be acceptable, but the aroma that results from dry hopping with hops over .5 is not acceptable. In addition, gushing appeared at an HSI of .6 in all three varieties.

A few numbers from deeper in the rabbit hole, showing the changes from .3 HSI to .7 (with stops along the way):

Alpha acids (percentage)

Celia 3.19 – 2.38 – 2.06 – 1.80 – 1.60

Styrian Wolf 11.87 – 8.66 – 9.21 – 7.71 – 7.66

Essential oil (percentage)

Celia 1.05 – 0.89 – 0.85 – 0.74 – 0.46

Styrian Wolf 2.22 – 1.49 – 1.28 – 1.07 – 1.02

Linalool (parts per billion)

Celia 783 – 699 – 527 – 484 – 443

Styrian Wolf 1061 – 944 – 793 – 943 – 925

Geraniol (parts per billion)

Celia 108 – 90 – 68 – 62 – 56

Styrian Wolf 421 – 337 – 268 – 296 – 292

Intensity of hop aroma (out of 5)

Celia 4.6 – 3.2 – 2.6 – 1.6 – 1.5

Styrian Wolf 5 – 4.6 – 4.1 – 3.0 – 1.9

Quality of hop aroma (out of 5)

Celia 4.7 – 4.3 – 3.1 – 1.9 – 2.0

Styrian Wolf 5.0 – 4.8 – 4.3 – 3.3 – 2.8

Intensity of bitterness (out of 5)

Celia 2.9 – 3.1 – 2.2 – 1.2 – 1.2

Styrian Wolf 2.2 – 2.4 – 3.3 – 3.7 – 4.2

Quality of bitterness (out of 5)

Celia 4.9 – 4.1 – 4.0 – 4.2 – 4.1

Styrian Wolf 5.0 – 4.9 – 4.9 – 4.4 – 4.0

German harvest & outlook

German hop-growers cooperative HVG (Hopfenverwertungsgenossenschaft) has provided more information about the 2022 harvest, confirming it was disappointing pretty much across all varieties. The estimated total harvest in Germany will be 35,850 metric tons, compared to 47,862 in 2021. A few individual varieties, with 2022 estimate first and 2021 totals second:

  • Mittelfrüh 750 (1,064)
  • Perle 4,500 (6,946)
  • Hallertau Tradition 3,800 (5,740)
  • Tettnanger 800 (997)
  • Herkules 16,000 (20,519)

Alphas were down, compared to both five- and 10-year averages, across the board. The report notes that farmers did not harvest enough to meet contracted commitments, but that breweries have sufficient amounts in inventory to balance stocks and reduce the amount of overcontracted hops. It concludes that “despite the bad crop, we expect that all breweries will get the hops they need for the upcoming brewing year.” Spot volume will be limited.

First wort hopping – legendary or myth?

It would seem that first wort hopping and decoction mashing are controversial brewing processes that were separated at birth. No matter what scientists measure in a lab, true believers are certain they can taste a difference. Johan Bartazzoni from HVG tossed the most recent log on the fire during Copa Mitad Del Mundo in Ecuador during a presentation titled “The Myth of First Wort Hopping.”

In 1995, the German brewing magazine Brauwelt reported on the “rediscovery of first wort hopping,” documenting that many German breweries implemented first wort hopping 100 years before.

It is a technique where hops are added to the first runnings of wort from the lauter tun. This exposes hop material to wort at lower temperatures and an elevated pH for an extended period of time. Advocates for FWH claim it produces a beer with improved bitterness qualities that can be described as “smooth” and “harmonious.”

Brauwelt reported that when two German breweries experimented with first wort hopping in 1995 they found the process resulted in beers with a finer hop aroma. Both breweries made two versions of a pilsner in very similar manners, including yeast pitching rates, brewing water, malt lots, and using Type 45 pellets. At Brewery A, the first wort addition of Tettnanger and Saaz hops amounted to 34 percent of the weight. At Brewery B, which used only Tettnanger, it was 53 percent. In both resulting beers the first wort-hopped beer had more IBUs, 39.6 to 37.9 at Brewery A, and 32.8 to 27.2 at Brewery B.

Despite increased bitterness, a tasting panel described the first wort-hopped beers as more pleasant tasting and overwhelmingly preferred them. Gas chromatographic analysis indicated the conventionally hopped beers contained a higher level of hop aroma compounds (particularly linalool), but panelists nonetheless described the first wort-hopped beers as having a very fine and rounded hop aroma and rounded hop flavor.

The authors of the study concluded, “… we recommend that first wort hopping be carried out with at least 30 percent of the total hop addition, using the later aroma additions. As far as the use of hops is concerned, the alpha acid quantity should not be reduced, even in the case of an improved bitterness utilization. The results of the tastings showed that the bitterness of the beers is regarded as very good and also as very mild. A reduction of the hop quantity could result in the bitterness being excessively weakened, and the good ‘hop flavor impression’ could be totally lost.”

The process was not unique to Germany. Jean-Marie Rock, long the director of brewing at the Orval Trappist monastery, said that Belgian breweries made first wort hop additions into the 1970s. Rock began brewing in 1972, making lagers first at Palm Breweries and then for Lamot in Mechelen. In 2010, a few years before he retired from Orval, Rock accepted an invitation from Steven Pauwels to collaborate on a recipe at Boulevard Brewing in Kansas City.

Rock knew immediately he wanted to revive the defunct technique. To make the strong pilsner, 8 per cent alcohol by volume with 30 bitterness units, they added two-thirds of all the Czech Saaz hops they would use before the outset of the boil.

Rock was happy with the result. “It has a taste you don’t get when you use late hopping,” he said at the time. “You get an old taste. That is my opinion.”

Pauwels, a native of Belgium who went to work at Boulevard in 1999, heard about the practice from other Belgian brewers as he learned his trade. He was told they wanted to keep the beer light in color, and the process allowed them to shorten the boil. “It wasn’t until later they found out the hop aromas carried over,” he said. “It seems like a contradiction. You’d think you’d get more bitterness and less flavor. It’s more subtle, almost crisper. Sometimes with late hopping it can get vegetative.”

Bertazzoni first presented the results of the newest study, conducted at the research brewery at St. Johann in Bavaria, earlier this year at the VLB International Craft Brewers Conference. The experimental trials included three beers: a control, in which hops were added at the beginning of the boil; a first wort beer, in which hops were added after 50 percent of the wort was collected; and an aerated first wort, with hops again added after 50 percent of the wort was collected.

Each beer was a pale lager fermented at 9°C (48°F). The hops were 2019 Diamant (.315 HSI), 2017 Hallertauer (.450 HSI) and 2020 Hallertauer (.33 HSI). An HSI value of .45 in whole hops was considered typical between 1900 and 1950.

The researchers found:

  • Bitterness. The aerated first wort beer had marginally higher IBU, which can be explained by the moderate increase of humuliones and hulupones. A “real increase in bitterness yield” was not observed.
  • Aroma compounds. The level of linalool was lower in the AFW beer, which can be attributed to oxidation. However, the difference was “miles away from a sensory impact.”
  • Sensory. The control beer rated higher than the other two in triangle tests, and overall difference sensory regimens did not produce meaningful differences.

They concluded that FWH provided minimal aroma and flavor contributions compared to late and whirlpool additions, and that FWH “does not significantly improve bitterness yield or bitter quality.”

Five years ago, Christina D. Hahn, a student at Oregon State University, and Dr. Thomas Shellhammer, who heads the brewing science education and research program there, presented a poster at the International Brewers Symposium on Hop Flavor and Aroma that came to a similar conclusion.

Research at OSU found “no perceivable sensory difference between the two treatments at a 95% confidence level.”

Students at the university pilot brewery “examined (the) claims by preparing two beers with the same mass of hops but varied in the timing of hop addition. The FWH beer was prepared by adding hops to the kettle prior to wort collection, while the reference beer was prepared by adding the hops to the wort at the start of boil.”

Although sensory evaluation found only minimal differences, chemical analysis indicated FWH could be responsible for positive foam characteristics. In addition, FWH can be utilized to reduce boil overs.

Topics to explore?

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