Sequential extraction of bitter acids and volatile compounds from hops using sub- and supercritical fluids: R134a vs. CO2

What if the key to unlocking hops' full potential lies not in a single solvent, but in a clever sequence of them? A new study reveals how switching between R134a and CO2 can selectively extract bitter acids and aromas from hops, like a master perfumer blending scents.

Hops are more than just beer's bitter soul—they're a treasure chest of bioactive compounds. But extracting them efficiently has always been a challenge. Now, researchers have pioneered a sequential extraction method using sub- and supercritical fluids, comparing R134a against the industry standard, CO2.

The study tested three temperature sequences, from a chilly 10°C to a warm 40°C, to see how each solvent behaves. R134a emerged as the yield champion, pulling out up to 22.5 grams per 100 grams of plant material. It excelled at recovering oxygenated compounds, hitting an impressive 51.36% recovery, while showing a knack for α- and β-acids and esters.

CO2, meanwhile, proved more selective than productive. It favored α-acids and oxygenated volatiles, especially at 40°C, and allowed for temperature-driven separation of compounds. The team used advanced analytical tools like UHPLC and GC-MS to quantify the bounty, revealing how solvent polarity and thermal programming can fine-tune extraction.

This isn't just lab curiosity. By offering a green, scalable strategy, this approach could transform how we produce functional extracts for food, beverages, and pharmaceuticals—making hops work harder, smarter, and cleaner.

Key Points

• R134a yields up to 22.5 g/100 g
• CO2 selects α-acids at 40°C
• Green sequential extraction for hops