Explicating the effect of the ozonation on quality parameters of onion (Allium cepa L.) in terms of pungency, phenolics, antioxidant activity, colour, and microstructure

ABSTRACT

Ozone is a powerful oxidizing agent, so its effect on quality parameters must be considered prior to any potential food application. The effect of gaseous ozone on the quality-related attributes of onion bulbs was examined. Onions were exposed to different ozone concentrations (100, 200, 300 ppm) at pulse mode (i.e., frequency of exposures 1, 2, 3). The pungency imparting pyruvic acid and ascorbic acid contents decreased with an increase in the concentration of ozone and the number of exposures, while total phenol and flavonoid content increased to an effective concentration of 400 ppm of ozone. Higher concentrations inadvertently decreased the antioxidant properties. Ozone treatment resulted in a non-significant decrease in firmness, anthocyanin content, and color of onion. Scanning electron microscopic analysis exhibited structural breakdown in the tunic (outer surface) of ozone-treated onion. At higher concentrations, structural changes were observed up to the first bulb scale.

KEYWORDS:

• Onion bulb
• gaseous ozone treatment
• phenolics
• antioxidant
• microstructure

Acknowledgments

The first author wishes to acknowledge the DST-Inspire fellowship (IF180395) received from the Department of Science and Technology (DST), Govt. Of India for carrying out the Ph.D. research work at ICAR-CIAE, the outreach program of PG school IARI.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author’s contribution

PSS: PhD student performed the experiment, conceptualized, and prepared the manuscript; DM: Chairperson, advisory committee, conceptualized the work, edited, and reviewed the manuscript; MKT and SKG: Members, Advisory Committee, provided the laboratory facilities, edited and reviewed the manuscript.