The ancient art of dry hopping (adding hops during fermentation and storage) saw a resurgence in America in the mid-1990s, sparking the first wave of craft beers. This technique brought out the raw hop character and fruity notes of varieties like Cascade, Centennial, and Chinook, leading to the creation of iconic beer styles such as American Pale Ale and the celebrated West Coast IPA.

By 2010, craft beer had gained a massive following, thanks in part to new hop varieties like Citra® and Mosaic®. Brewers began pushing the boundaries with higher hop dosages, culminating in the wildly popular NEIPAs (New England IPAs), which can use up to 5kg of hops per hectoliter.

These bold recipes presented unique challenges for brewmasters and equipment manufacturers, as the brewing technology of the 1990s and 2000s struggled to handle such large quantities of hops. As a result, larger breweries were slow to adopt these innovative craft beer styles.

Addressing the process-related difficulties, such as overloading whirlpools and tanks, dosing, and separating hops, became crucial. Additionally, ensuring process reliability, flexibility, and managing economic factors—like raw material costs, investment in specialized systems, and beer losses—grew increasingly important with higher hop dosages.

Enter BarthHaas from Nuremberg, Germany. After years of intensive research and development they’ve introduced a groundbreaking solution with their new liquid hop product, Spectrum.

This soluble, 100% natural hop product, is manufactured through a patented process by BarthHaas UK and is free of emulsifiers or carriers and preserves the typical variety characteristics while maintaining a stable oil content and minimizing natural variations in the brewing process.

Beer Losses

When it comes to beer losses, brewers using hop pellets must consider both yield and cost. Tests have shown that 1kg of hop pellets can absorb up to 14 liters of beer. By using Spectrum, which is fully soluble and free of solids, these losses can be completely eliminated (see Table 1).

Table 1: Beer losses

Hop Creep

Hop creep is a phenomenon where hop enzymes break down non-fermentable polysaccharides into fermentable sugars during dry hopping. This leads to increased alcohol levels, CO2 production, and potential additional Diacetyl formation. However, with Spectrum, hop creep can be significantly reduced or eliminated. The production process of Spectrum inactivates the relevant hop creep enzymes (see Figure 1).

Figure 1: Hop Creep Reduction by Spectrum

Bitterness

Quality parameters such as bitterness behave differently with Spectrum. While iso-alpha acids typically decrease due to adsorption on hop particles, the IBU (International Bitterness Units) can increase because of additional bitter acids.

Although alpha acids are poorly soluble at typical beer pH values, dry hopping can cause a significant increase in alpha acids. However, alpha acids’ bitterness is only about ten percent of that of iso-alpha acids, meaning the spectrophotometric bitterness value doesn’t always correlate well with sensory or calculated bitterness.

Humulinones (oxidized alpha acids) from hop pellets or cones are highly soluble and significantly contribute to bitterness, with an iso-alpha bitterness of around 70%. Increasing the dosage with pellets can significantly shift both analytical and sensory bitterness.

In contrast, the use of Spectrum minimally alters the composition of bitter acids. Iso-alpha acids remain in solution, and humulinones are not introduced, resulting in minimal impact on beer bitterness (see Table 2 and Figure 2).

Table 2. Content of various bittering substances

Figure 2. Content of various bittering substances