Rapid testing for food antioxidants developed by researchers in Japan

16 Nov 2020 --- Measuring food’s antioxidant capacity can now be done quickly and easily with a new system developed by researchers from Kumamoto University in Japan. Applications for the technology are quality control in the production, manufacturing and sale of food products, such as meat, fish, vegetable and fruits.

This system significantly simplifies the conventional method and can easily be used by anyone anywhere, according to the researchers. 

“This technology is completely different from the conventional colorimetric method where solid food samples are crushed and placed in a solution for measurement. Our system allows us to analyze a sample in less than a minute everywhere,” Professor Masashi Kunitake, who led the research group, tells FoodIngredientsFirst. 

The new electrochemical system uses a gel form bicontinuous microemulsion and integrates it with sheet electrodes to simplify the measurement process.

“Our system can be used to monitor the deterioration of food due to oxidation. Our method is an in-situ extraction and measurement technology that uses ultra-thin film. Cross-sections of solid foods can be brought into direct contact with the electrode,” he explains. 

By contrast, conventional evaluation methods require complex separation, extraction and colorimetric analysis, which makes it difficult to measure fat-soluble antioxidants in colorful or cloudy food samples.

Fat-soluble antioxidants, such as vitamins and polyphenols, are easily soluble in oil rather than water.

The evaluation of fat-soluble antioxidant capacities using the currently known colorimetric analysis has several difficulties.

“The turbidity and color of fat-soluble antioxidants make them difficult to evaluate as many of them possess color. Furthermore, the colorimetric method requires pretreatment and extracting important components using an organic solvent,” explains Kunitake. 

Improving food with antioxidants
Nevertheless, it is important to evaluate the antioxidant capacity of food to maintain a healthy diet. Antioxidants inhibit the generation of highly reactive oxygen species, which can lead to arteriosclerosis, cancer and decreased immune function, notes the paper that describes the new technology. 

The gel membrane on the electrodes functions as its own solution, eliminating the need to prepare an electrolyte solution (Credit: Professor Masashi Kunitake).Kunitake believes this system can contribute to increased healthy food production for society by making the process more available.

“If the analysis of food products becomes more accessible to producers and consumers, it could give added value to food products, help find the best cultivation conditions for production, and eventually become a criterion for judging whether food products are both tasty and safe to eat.”

Simplifying testing
Normally, an electrochemical analysis is taken by dissolving a sample into an electrolyte solution and measuring the currents from three electrodes (working, reference and counter). 

However, in the new system, the gel membrane affixed to the electrodes acts as its own electrolyte solution. Even oily substances that are not soluble can be analyzed in their original state without separation and extraction. 

The system’s electrodes are simply dipped into the sample or a drop of the sample is placed on the electrode – with no extensive equipment or special treatment required. 

This system has already been used to measure vitamin E in commercial olive oil as proof of concept.

“The method does not determine the individual concentration of antioxidants, but it does determine the fat-soluble antioxidant capacity and hydrophilic antioxidant capacity overall,” Kunitake adds. 

The research team’s ultimate goal is to develop a technology that takes accurate measurements by simply touching a target sample. 

By Missy Green