How to extract allicin from onions?

How to Extract Allicin from Onions

Allicin, the compound best known for its presence in garlic, is also found in smaller amounts in onions. While it’s celebrated for its potential health benefits—like antimicrobial and antioxidant properties—extracting it efficiently isn’t straightforward. Unlike simple juice extraction, isolating allicin requires more sophisticated methods due to its unstable nature and the way it’s formed in the plant.

Common extraction techniques include solvent extraction, ultrasound-assisted extraction (UAE), pressurized liquid extraction (PLE), and supercritical carbon dioxide extraction (SCCO2). Each has its advantages, but they also come with notable drawbacks. Solvent extraction, for example, often relies on organic chemicals that can leave residues and raise concerns about purity. UAE speeds things up with sound waves but may still require solvents and additional processing steps.

One of the bigger challenges lies in the biology of allicin itself. It isn’t present in the onion as-is; instead, it’s created when the enzyme alliinase acts on a precursor compound, alliin, after the plant cells are damaged—say, by cutting or crushing. This means a successful extraction often requires not just breaking down the plant material, but also allowing time for the enzymatic reaction to occur before capturing the resulting allicin.

As a result, most methods end up being two-step processes: first activating the enzyme, then extracting the compound. This increases complexity, time, and cost. Techniques like PLE and SCCO2 offer cleaner profiles—especially SCCO2, which avoids solvents altogether—but they require expensive equipment and technical expertise.

For now, while science continues to refine gentler, faster, and more sustainable extraction methods, the process remains a careful balance between efficiency and integrity. The goal is clear: capture allicin’s potential without losing it in the process.