This study presents the effects of ozone treatment on microbial status and contents of selected bioactive compounds in marjoram plants. Origanum majorana L. is a widely used plant which in the course of production is affected by microbial infections. One of the ways to reduce microbial load involves application of a strong oxidant, such as ozone. In order to determine the effects of ozonation, a number of analyses were carried out including microbiological tests (aerobic colony count, yeast and mould count, and mesophilic lactic acid bacteria count) and chemical tests assessing total antioxidant potential, total polyphenols, and volatile fraction composition. Ultimately, the findings showed considerable (6-log) reduction in microbial load, with unchanged composition of headspace volatile compounds. Furthermore, the raw material obtained presented elevated the contents of the selected bioactive compounds. It was shown that the most beneficial effects are achieved when ozone treatment is applied at a rate of 1 ppm for a duration of 10 min.
Keywords: HS-SPME; antioxidant potential; fumigation; herbs; microbial load; ozone; polyphenols.