Ozonation in Pseudomonas paracarnis control: biofilm removal in stainless steel and preservation of chicken meat during refrigerated storage
Authors:   , Okolo Ejima Akogwu 
Published: March 2023

Ozone is a highly oxidizing agent and it is effective against many types of pests in food. Ozonation has shown the potential to remove microbial biofilms on materials such as stainless steel and polypropylene and to inactivate microorganisms in food. Meat can be contaminated with a large variety of pathogenic and spoilage microorganisms during slaughtering, processing, and storage periods. Among the microorganisms that can cause deterioration in meat and meat products, the Pseudomonas species stand out. Then, the objectives of this work were: i) to determine the effect of ozonated water in the removal of Pseudomonas paracarnis biofilm on stainless steel; and ii) to determine the effect of ozone gas and ozonated water on inactivating P. paracarnis in deboned chicken breast meat and its effect on color of the product. The research was divided into two steps. In the first step, the ozonated water was evaluated in the removal of Pseudomonas paracarnis biofilm from stainless steel material. AISI 304 coupons with dimensions 1.0 cm x 1.0 cm were used as a surface for biofilm formation. To obtain ozonized water, two different systems were used: system with microbubble generator (MB) and system with porous stone diffuser (PSD), with inlet ozone concentration of 19 mg/L, for 15 min and flow rate of 1 L/min. In the second step, the gaseous and ozonated water were evaluated to inactivate Pseudomonas paracarnis in chicken meat and its effects on color of the product. To obtain ozonized water, the column method with porous stone diffuser (PSD) was used. For the treatment of chicken meat with ozone gas, the inlet concentration was 0.30 mg/L and flow rate of 3.0 L/min. The exposure time for chicken breast meat was 40 min. After the ozonation process, chicken meat samples were stored in the refrigerator at 8 °C, for five days. The microbiological analysis of chicken breast samples was done immediately after ozonation (day 1) and also, after five days (day 5). Water activity and color (luminosity, chroma, hue angle, and color difference) of chicken breast were analyzed. The experiment was carried out in a completely randomized design, with three replications. The analysis of variance (ANOVA) was performed and Tukey test at 5.0% significance was applied, using StatPlus 5.0 software. More expressive reductions that differed from the control treatment (immersion in sterilized water) were obtained when using ozonized water obtained in the system with microbubble generator (MB - 20 min) and system with porous stone diffuser (PSD-10 min and PSD-20 min). For the systems with microbubble generator and with porous stone diffuser, the reductions were 2.3 (MB20), 2.7 (PSD10) and 2.6 (PSD20) log cycles. The treatment of chicken meat with ozone gas resulted in lower counting of P. paracarnis, when compared with the control treatments and with ozonized water, both immediately after ozonation (day 1) and after five days of storage. There was no significant difference in water activity (aw) in chicken samples due to the interaction between treatment (with and without ozone) and days of storage. The average chroma value referring to the treatment with ozone gas (7.48±1.12) was higher than those obtained for the control treatments (5.64±0.97) and with ozonized water (5.61±0.89). The luminosity in the chicken meat samples treated with ozonized water (64.1±1.7) was higher than that verified in the control treatments (55.9±1.7) and with ozone gas (57.2±1.8), immediately after ozonation (day 1). A similar trend was observed in hue angle and color difference, in which the highest values were obtained for treatment with ozonized water. Based on the results obtained in this study it was concluded that: i. Ozonated water can be used to remove P. paracarnis biofilm from stainless steel under static conditions; ii. Gaseous ozone is more efficient in the inactivation of P. paracarnis from chicken breast meat, when compared to ozonated water; iii. Immersion in ozonized water for 40 min causes changes in the color of chicken meat, specifically in luminosity, hue angle and color difference. Keywords: Ozone gas. Ozonated water. Pseudomonas paracarnis. Chicken meat. Color.