Impact of gaseous ozone treatment of fish carcasses (Gadus morhua) on the microbiological load and their quality

The improvement of the microbial quality of food products is one of the most important aspects of the world economy with a significant impact on the health of consumers. Due to the content of lipids, water, and proteins, meat is highly susceptible to degradation mediated by enzymes or microorganisms. Among the wide variety of animal-derived consumption products, fish is highly perishable and characterized by a short shelf life. To improve safety and microbial quality during storage, fish food can be treated with ozone, which is a highly potent antimicrobial agent. In this study, the effect of ozone treatment on the total microorganism content and the quality of fish food was investigated with respect to the content of lipids and the volatile faction responsible for the characteristic odour. The content of microorganisms in fish food subjected to an atmosphere enriched with ozone was reduced. For example, for the control sample with 1.8 x 103 cfu, which was exposed to 20 ppm ozone in atmosphere during the exposition time in the range 10-30 min, a microbial load was reduced to a level between 1.6 x 103 and 1.2 x 103 cfu. The observed reduction levels indicated that such an ozone treatment procedure can be declared as an viable option for improvement of microbial safety of fish. However, the presence of ozone caused qualitative changes of chemical parameters of the fish matrix; in particular, oxidation of lipids occurred. The extent of those changes increased with the extension of the exposition time..