P-34 - Exploring How Emulsified Hop Oil Products Affect Beer Flavor

At a time when brewers are trying to keep costs low, many have turned to emulsified hop oil products  to maximize their hop utilization, due to their high solubility in beer. This study explores how emulsified hop oil products affect beer flavor when dosed in the fermenter or keg.

The oil profile of most hops is primarily made up of mono- and sesqui- terpenes (myrcene, humulene, caryophyllene). These classes of compounds are characterized by high volatility and low solubility in beer, as shown through internal GC/MS analysis. More soluble compound classes like monoterpene alcohols and esters thus contribute significantly to beer flavor, despite their relatively low concentration in hops.

It is expected that when dosed in the fermenter or keg, emulsified hop oils will create a beer that has a different sensory profile than a beer made with non-emulsified hop oil products. This is because a greater proportion of normally insoluble compounds should be found in the beers dosed with emulsified hop oils. Two brewing trials were conducted in the Yakima Chief Hops pilot brewery to test this hypothesis.

The first trial was a lager, dry hopped conservatively with Loral® T-90 pellets at 2g/L. The final beer was split into six different kegs, receiving either: no dose, varying levels of YCH 805 (an emulsion of 2% hop oil in propylene glycol), or YCH 803 (a non-emulsified pure hop oil product currently in development). Keg doses were injected into the beer stream during filling. This experimental design allowed for the comparison between emulsified and non-emulsified hop oil doses, along with a control.

The second trial utilized a pale ale base which was dry hopped at 10g/L with T-90 pellets. The final beer was split between four kegs, and each was dosed with varying levels of YCH 805. Additionally, a test was conducted using the same wort steam to determine how YCH 805 performed when used during active fermentation.

Beers were assessed by Yakima Chief’s internal beer sensory panel and were also tested for aromatic compounds via GC/MS.

Results from the tests showed a large increase in the amount of myrcene in the final beers that were dosed with YCH 805, but only minor increases were observed for more  desirable compounds like linalool. When dosed during active fermentation, normally insoluble compounds were able to remain in solution.

Sensory results indicated that very low doses of YCH 805 yielded similar or slightly more desirable flavor profiles in beer, compared to the controls. However, at higher doses, aroma intensity was reduced, which may have been driven by sensory masking. At extremely high doses, more intense aromas of earthy, grassy, and vegetal were detected by the panel. This indicates that increased concentrations of terpenes in beer may not be desirable and maximum dose rate should be established for emulsified oil products