The objective of this study was to compare the physico-chemical characteristics and antioxidant activity of ozone-treated papaya fruit and untreated fruit. Freshly harvested papaya fruit were exposed continuously to ozone fumigation (0, 1.5, 2.5, 3.5 and 5ppm) for 96h prior to ambient storage at 25±3°C and 70±5% relative humidity (RH) for up to 14days. The fruit exposed to 2.5ppm ozone had higher levels of total soluble solids (25.0%), ascorbic acid content (12.4%), β-carotene content (19.6%), lycopene content (52.1%), and antioxidant activity (30.9%), and also reduced weight loss (11.5%) at day 10 compared to the control. The sensory attributes of papaya treated with 2.5ppm ozone was superior in sweetness and overall acceptability. These results support the application of ozone as a non-thermal and safe food preservation technique for papaya which can benefit both the producers and consumers.
Application of ozone is recommended for sterilisation in dental procedures. This study explored the antimicrobial effect of 0.1 ppm ozonated-water on selected common oral commensals. Based on deviation of their growth curves pattern upon ozone treatment, the inhibitory effect of ozone was determined. SEM examination of the ozone-treated microbes recorded its possible morphological effect. Findings suggested a bacteriostatic action of ozone when microbes were treated at the early phase, while, it was bactericidal when treated during the active phase of the growth cycle. Hence, suggesting rinsing the oral cavity with ozonated-water at 0.1 ppm immediately after tooth brushing may suppress microbial growth and slow biofilm formation. While, rinsing on already developed biofilm may result in microbial cell lysis that halted microbial growth and reduce microbial population in the biofilm. Both justify the great potential of ozone (0.1 ppm) for use as antimicrobial agent for the control of biofilm development in the oral cavity.
Disinfectants are generally used to inactivate microorganisms in solutions. The process of inactivation involves the disinfectant in the liquid diffusing towards the bacteria sites and thereafter reacting with bacteria at rates determined by the respective reaction rates. Such processes have demonstrated an initial lag phase followed by an active depletion phase of bacteria. This paper attempts to study the importance of the combined effects of diffusion of the disinfectant through the outer membrane of the bacteria and transport through the associated concentration boundary layers (CBLs) during the initial lag phase. Mathematical equations are developed correlating the initial concentration of the disinfectant with time required for reaching a critical concentration (C*) at the inner side of the membrane of the cell based on diffusion of disinfectant through the outer membranes of the bacteria and the formation of concentration boundary layers on both sides of the membranes. Experimental data of the lag phases of inactivation already available in the literature for inactivation of Bacillus subtilis spores with ozone and monochloramine are tested with the equations. The results seem to be in good agreement with the theoretical equations indicating the importance of diffusion process across the outer cell membranes and the resulting CBL's during the lag phase of disinfection.