Search

Bacterial biofilms formed on equipment surfaces are potential sources of cross-contamination and can be responsible for the spread of bacteria involved in food spoilage, such as some Enterobacteriaceae family members. In this study, the effect of chlorite-based disinfectants, including sodium hypochlorite (SH), chlorine dioxide (CD), strongly acidic electrolyzed water (StAEW), and neutral electrolyzed water (NEW), on inactivation of mono-biofilms of Enterobacter cloacae, Klebsiella oxytoca, and Citrobacter freundii was evaluated separately. All the strains were enumerated by the viable plate-count method after disinfection for 30 min. A comparison of the surviving cells after disinfection indicated that E. cloacae biofilms were more resistant to disinfectants than the biofilms of the other two strains, and treatment with all the disinfectants improved sanitizing. SH (200 mg/L) was the most effective in the reduction of cell number in the biofilms of all strains. Considering the safety of use and environmental protection, electrolyzed oxidizing water, especially StAEW, was a good suggestion for the inactivation of cells in K. oxytoca or C. freundii biofilms. These results suggest that the cells in biofilm of E. cloacae, K. oxytoca, and C. freundii were highly sensitive to chlorite-based disinfectants and provide insights into the efficacy of disinfectants in killing bacteria., Practical Application: The Enterobacteriaceae biofilms formed on equipment surfaces, which can cause cross-contamination and food spoilage, are greatly challenging bacterial contaminants of food products. Electrolyzed oxidizing water is a novel, environmentally friendly disinfectant that can effectively treat Enterobacteriaceae biofilms. The results of this study may be used to design effective measures to disinfect biofilms on equipment contact surfaces., (© 2018 Institute of Food Technologists®.)

Abstract As a novel broad-spectrum disinfectant, acidic electrolyzed water (AEW) has been widely used, but it is generated on-site for one-time used and usually not stored. but "producing once for using once" is not a convenient mode for industrial application. This study focused on modeling the degradation of the available chlorine concentration (ACC) of AEW during storage and its ability to disinfect a dual-species biofilm formed by Salmonella Enteritidis and Pseudomonas fluorescens. The results showed that temperature had no significant effect on the ACC, while the ACC gradually decreased with time. The degradation process of the ACC could be fitted very well using the Weibull model. Dual-species biofilms comprising S. Enteritidis and P. fluorescens were inactivated by 20 and 40 mg/L AEW. The number of viable cells on stainless steel gradually decreased as the treatment time increased. Immersion for 10 and 30 min led to > 2 log CFU/cm2 and 4.5 log CFU/cm2 in decrease of the cells in dual-species biofilms when treated with 20 and 40 mg/L AEW, respectively. In addition, the dual-species biofilm displayed more resistance than the single-species biofilm. The findings presented herein could provide useful information for the application of AEW in food processing environments. Highlights • Weibull model could be used to fit the degradation of ACC of AEW. • Survival rate of cells in biofilm seriously depended on treatment time and ACC. • Dual-species biofilm displayed more resistance than the single-species biofilm. [ABSTRACT FROM AUTHOR]

Abstract: Bacterial biofilms formed on equipment surfaces are potential sources of cross‐contamination and can be responsible for the spread of bacteria involved in food spoilage, such as some Enterobacteriaceae family members. In this study, the effect of chlorite‐based disinfectants, including sodium hypochlorite (SH), chlorine dioxide (CD), strongly acidic electrolyzed water (StAEW), and neutral electrolyzed water (NEW), on inactivation of mono‐biofilms of Enterobacter cloacae, Klebsiella oxytoca, and Citrobacter freundii was evaluated separately. All the strains were enumerated by the viable plate‐count method after disinfection for 30 min. A comparison of the surviving cells after disinfection indicated that E. cloacae biofilms were more resistant to disinfectants than the biofilms of the other two strains, and treatment with all the disinfectants improved sanitizing. SH (200 mg/L) was the most effective in the reduction of cell number in the biofilms of all strains. Considering the safety of use and environmental protection, electrolyzed oxidizing water, especially StAEW, was a good suggestion for the inactivation of cells in K. oxytoca or C. freundii biofilms. These results suggest that the cells in biofilm of E. cloacae, K. oxytoca, and C. freundii were highly sensitive to chlorite‐based disinfectants and provide insights into the efficacy of disinfectants in killing bacteria. Practical Application: The Enterobacteriaceae biofilms formed on equipment surfaces, which can cause cross‐contamination and food spoilage, are greatly challenging bacterial contaminants of food products. Electrolyzed oxidizing water is a novel, environmentally friendly disinfectant that can effectively treat Enterobacteriaceae biofilms. The results of this study may be used to design effective measures to disinfect biofilms on equipment contact surfaces. [ABSTRACT FROM AUTHOR]

Microorganism biofilms can form on food-contact surfaces and lead to cross-contamination of bacteria during food processing. The dynamics of biofilm formation by Pseudomonas fluorescens associated with meat spoilage and the resistance of established biofilm to four disinfectants were investigated in this study. The results indicated that more than 4.5 log CFU/cm 2 of P. fluorescens were transferred to a stainless-steel surface under short-term (5 h) scenario, and bacteria transfer occurred even after only 10 min exposure. A mature biofilm was discovered after 5 days of incubation under long-term (7 days) scenario. The biofilm was characterized by more than 9.5 log CFU/cm 2 cells, 120 μm thick and a large amount of extracellular polymeric substances. Observation of mature biofilm were further confirmed by confocal laser scanning microscopy and attenuated total reflection fourier-transformed infrared spectroscopy. The established biofilm showed distinct resistance to four disinfectants, namely sodium hypochlorite (SH), chlorine dioxide (CD), slightly acidic electrolyzed water (sAEW) and acidic electrolyzed water (AEW). The cells reduction was significant dependent on the concentrations, almost 8.0 log CFU/cm 2 of biofilm cells were reduced by 40 mg/L AEW and 200 mg/L SH treatment for 30 min, below the detection limit (1.32 log CFU/cm 2 ). However, less than 3 log CFU/cm 2 reduction of biofilm cells were obtained after treatment with 40 mg/L sAEW and 20 mg/L CD for 30 min, remaining large numbers of biofilm survival. Meanwhile, the cells reduction was time-dependent, and the numbers of surviving cells rapid declined along with increasing time, but there was no additional log reduction when treatment of 20 mg/L CD was increased from 15 to 30 min. The finding suggested that AEW has great potential to be used as an environmentally friendly intervention alternative for the elimination of P. fluorescens biofilm, substituting for the traditional sodium hypochlorite in the food industry. [ABSTRACT FROM AUTHOR]

Aeromonas spp. are closely associated with food spoilage, and often enter the food chain through cross-contamination during processing from biofilms on food-contacted surfaces. The attachment abilities of two high-spoilage Aeromonas salmonicida isolates were compared. The sensitivities of these isolates in biofilm to four disinfectants, namely sodium hypochlorite, chlorine dioxide, acidic electrolyzed water (AEW) and neutral electrolyzed water (NEW), were assayed. The results indicated that isolate 1425 showed higher attachment ability as compared to isolate 1435 at initial attachment (30 min) under a short-term attachment scenario (5 h), reaching more than 5 log CFU/cm 2 . Under a long-term attachment scenario (7 days), isolate 1425 formed a mature biofilm after 5 days of incubation, with the highest observed cell numbers of nearly 9 log CFU/cm 2 . The dynamics of biofilm formation of isolate 1435 were relatively stable, with cell population ranging from 6.25 to 7 log CFU/cm 2 . The composition of the extracellular polymeric substances and the morphology of the mature biofilm were identified by Attenuated Total Reflection Fourier Transform Infrared spectroscopy (ATR-FTIR) and Confocal Laser Scanning Microscopy (CLSM). The mature biofilm formed by isolate 1425 showed more resistance to tested disinfectants than that of isolate 1435. Sodium hypochlorite (200 mg/L) and AEW (40 mg/L) showed greater lethal effects than the other disinfectants. Moreover, 40 mg/L of AEW was as effective as 200 mg/L of sodium hypochlorite. These findings indicated that the biofilm formed by microorganisms associated with food spoilage and safety could not be ignored during food processing and that AEW may be a promising alternative to sodium hypochlorite for the elimination of such biofilms. [ABSTRACT FROM AUTHOR]