Correlation Study of Biological Activity with Quercetin and Phenolics Content in Onion Extracts

In this study it was shown that the fungistatic and antioxidant activities of onion extracts are related to the type of liquid used as the extractant and the technique of its preparation. A change in the antioxidant properties of white and red onion extracts was demonstrated with the change of the temperature of the pressurized hot water extraction process, which can be easily related to the changes accompanying the process of thermal processing of vegetables and fruits during cooking. Owing to the experimental and mathematical approaches concerning both the main and characteristic components of onions, i.e., quercetin and phenols, respectively, with the biological activity of the extracts, it was possible to demonstrate the significant share of these compounds in the antifungal and antioxidant properties of the extracts. Considering that the research was carried out, inter alia, on onion husks, demonstrating a very high potential of biological properties of this waste material from agricultural production, the research results presented in the paper should encourage the popularization of the use of this so far underestimated raw material for the production of various functional materials.

Automated summary

This study showed that the fungistatic and antioxidant activities of onion extracts depend on the type of liquid used for extraction and the extraction technique. The antioxidant properties of white and red onion extracts were found to change with the temperature of the pressurized hot water extraction process, which is similar to the changes that occur during cooking. The research demonstrated the significant contribution of quercetin and phenols, the main components of onions, to the antifungal and antioxidant properties of the extracts. The study's findings suggest that onion waste materials, such as onion husks, have high potential for producing functional materials and should be popularized.