Systematic study on active compounds as antibacterial and antibiofilm agent in aging onions

Area of Science:

• Food Science
• Phytochemistry
• Microbiology

Background:

• Onions are a rich source of bioactive compounds with potential health benefits.
• The impact of aging on the phytochemical profile and biological activities of onions requires further investigation.
• Understanding these changes can optimize the use of onions in food and pharmaceutical applications.

Purpose of the Study:

• To quantitatively assess quercetin, total phenolics, flavonoids, and antioxidant, antibacterial, and antibiofilm properties of methanolic onion extracts.
• To compare the biological activities of fresh versus aged onions across six different varieties.
• To identify onion varieties with superior biological activities after storage.

Main Methods:

• Spectrophotometric analysis using Folin-Ciocalteau's reagent for total phenolic content.
• FRAP and DPPH assays for total antioxidant activity.
• Kirby-Bauer disc diffusion and crystal violet assays for in vitro antibacterial and antibiofilm activities, respectively.

Main Results:

• Total phenolic and antioxidant content increased with onion aging across all varieties.
• Red-skinned onions (Happyhong) stored for three months exhibited the highest total phenolics and flavonoids.
• Antibiofilm activity was most effective with extracts from onions stored for three months.
• Quercetin content and overall biological activity increased with aging in stored onions.

Conclusions:

• Onion aging enhances the concentration of key phytochemicals and improves antioxidant, antibacterial, and antibiofilm properties.
• Storage duration and onion variety significantly influence the biological efficacy of onion extracts.
• Aged onions, particularly red varieties, represent a valuable source of bioactive compounds for potential therapeutic and functional food applications.