Korean team pioneers unopened bottle test to spot omega-3 in cooking oils

A team of Korean scientists, including researchers from Yonsei University Health System, has unveiled a new technique that can determine the amount of omega-3 fatty acids in edible oils without opening the container.

Omega-3 fatty acids are known for a wide range of health benefits, including lowering triglyceride levels, improving vascular function, preventing Alzheimer’s disease, and inhibiting cancer cell growth.

Alpha-linolenic acid, a plant-derived omega-3 fatty acid, is essential because it cannot be synthesized by the human body and must be obtained through diet. Perilla oil, which consists of about 60 percent alpha-linolenic acid, is considered one of the most health-promoting edible oils.

However, some commercial products labeled as “perilla-flavored oil” contain less than 20 percent perilla oil, making accurate omega-3 content verification crucial.

Conventional methods for analyzing fatty acid content, such as nuclear magnetic resonance (NMR) and gas chromatography, are limited by high cost and lengthy processing times.

To resolve this issue, the team, led by Professors Oh Seung-jae, Yang Lan-hee, and Maeng In-hee of the Medical Convergence Research Institute at Yonsei University Medical Center and Korean Research Institute of Biosience and Biotechnology, applied terahertz time-domain spectroscopy (THz-TDS).

Professors Ji Young-bin and Bark Hyeon-sang of the Division of Applied Photonics System Research at Gwangju Institute of Science and Technology, and Shin Hee-jun of the Pohang Accelerator Laboratory at POSTECH also participated in the study.

Terahertz waves, which lie between microwaves and infrared light on the electromagnetic spectrum, are harmless to the human body and possess strong material penetration capabilities.

Notably, they allow non-destructive, non-contact, and real-time analysis while being highly sensitive to molecular structural changes, making them attractive for next-generation medical diagnostics.

The research team tested various edible oils, including soybean, corn, and perilla oil, comparing the results of terahertz spectroscopy with conventional methods.

NMR analysis showed alpha-linolenic acid levels of 58.5 percent in soybean oil, 3.6 percent in corn oil, and 8 percent in perilla oil.

Fourier-transform infrared spectroscopy confirmed the molecular structures. When the same oils were analyzed with terahertz spectroscopy, the results matched traditional measurements, proving the reliability of the new technique.

Oils with higher alpha-linolenic acid content showed proportionally higher refractive indices and absorption coefficients, allowing researchers to quantify omega-3 levels by observing these optical properties.

The team also demonstrated that the method could distinguish omega-3 content by measuring the reflection of terahertz waves from unopened bottles of oil. Because reflection values vary according to fatty acid concentration, the technique makes it possible to evaluate omega-3 levels without sampling or pre-treatment.

“This study is the first to analyze omega-3 content using terahertz technology,” Professor Oh said. “It shows the feasibility of simple, non-contact, non-destructive, and real-time verification of edible oils in sealed containers, opening the door to new applications of terahertz spectroscopy.”

The study was published in the npj science of food.