Impact of gaseous ozone on microbial contamination and quality of fresh-cut durian

Abstract

The present study investigated the effect of gaseous ozone on reducing microbial contamination and maintaining the shelf life of fresh-cut durian. The effect of ozone gas at 0 (control), 100, 200, 300, 400, 500, 600, 700, 800, 900, and 1,000 mg L−1 for 3 and 5 min on the decontamination of coliforms (major microbes found in preliminary study) were determined in an in-vitro test. The results highlighted that the effectiveness of ozone increased with increased concentration, which, 500 mg L−1 onward, could inhibit coliforms completely. However, the ozone treatments for 3 and 5 min were not significantly different in inhibiting coliform growth. A preliminary study on the effect of ozone at 500–1,000 mg L−1 for 3 min on the visual appearance of fresh-cut durian was evaluated before the study in the in-vivo test. Ozone treatments at 500–900 mg L−1 did not affect the appearance of the flesh and funiculus of fresh-cut durian but at 1,000 mg L−1 caused water-soaking and browning on the funiculus. Therefore, ozone at 500 and 900 mg L−1 was selected for reducing microbial contamination in an in-vivo test. The experiment was performed by fumigating fresh-cut durian with ozone at 500 and 900 mg L−1 for 3 min, and a non-treated sample served as the control. All samples were packed in polyethylene terephthalate (PET) clamshell and stored at 4 °C for 14 d and then transferred to 10 °C and 25 °C for 1 d for stimulating the shelf-life condition. The results showed that ozone treatment at 500 and 900 mg L−1 significantly reduced the microbial contamination of fresh-cut durian compared to the control. Ozone at 900 mg L−1 was the best treatment, which could reduce total bacteria and coliforms by 2.72 and 1.93 log CFU g−1, respectively, compared to the control. Thus, the effect of ozone at 900 mg L−1 on maintaining the quality of fresh-cut durian was investigated. The results implied that ozone at 900 mg L−1 could maintain flesh firmness, reduce the respiration rate and ethylene production, enhance the antioxidant capacity and total phenolic content, and did not adversely affect the flesh color and sensory properties (flavor and overall appearance). These results prove that gaseous ozone is an alternative technology to minimize microbial loads and maintain the quality of fresh-cut durian for 15 d