The influence of different methods of decontamination of microbial biofilms formed on eggshells

Abstract

According to "food legislation" requirements, all eggs entering the production of egg products must be disinfected. Therefore, developing technologies for decontaminating chicken eggs before use for food purposes is a promising work direction in chicken egg production and storage. This research aimed to identify the microbiota of chicken eggs with varying degrees of shell contamination and determine the influence of different methods of decontaminating microbial biofilms formed on eggshells. It was set up that the quantitative content of microorganisms on the surface of chicken eggs ranged from 103 CFU to 106 CFU/ml of washing and depended on the contamination of the shell with droppings. Lactobacillus spp., Bacillus spp., Corynebacterium, Staphylococcus were among the genera of bacteria that prevailed on the clean chicken shell, which were isolated in 30-50% of cases, and gram-negative microbiota was practically absent. The constant release of gram-positive bacteria is noted on the contaminated eggshell, and the frequency of identification of gram-negative microbiota of the Enterobacteriaceae genus and non-fermenting genera Pseudomonas and Psychrobacter increases. That is, the microbial scape of the microbiota of the chicken shell depends on its cleanliness, and the presence of a dirty surface increases the frequency of allocation of the resident microflora of the gastrointestinal tract. It was found that the working solution of the disinfectant Vircon S destroyed planktonic bacteria applied to the eggshell in an average of 2 minutes of exposure, stabilised water ozone for 1 minute, gaseous ozone for 3 minutes, and the action of ultraviolet rays with a length of 253.7 nm for 25-30 min. At the same time, using these disinfection methods on bacteria formed in a biofilm on the eggshell did not cause a bactericidal action during this time. To significantly reduce bacteria in the biofilm using these methods, it is necessary to increase the exposure time of the biocide by 2-3 times. Therefore, the complex structure of the eggshell and the multi-layered matrix of biofilms provide better protection for bacteria against the influence of the investigated disinfection methods.