Microbial methods for assessment of cleaning and disinfection of food-processing surfaces cleaned in a low-pressure system.

摘要

An assessment system for detection of residual, surface-attached microbes and surface soil after sanitation using microbial detection methods was developed. Microbial detection methods used were: conventional cultivation methods; image analysis microscopy used in conjunction with acridine orange (AO), 5-cyano-2,3-ditoyl tetrazolium chloride/4',6-diamidino-2-phenylindole (CTC-DAPI), and LIVE/DEAD stains; impedance measurements, viable counts using 2,3,5-triphenyltetrazolium chloride (TTC) agar; and ATP measurements. The trial test rig used 4 low-pressure cleaning procedures (pressure less than 20 bar, flow rate 27 l/min). A strong alkaline foam cleaner, Trippel, and a mild alkaline foam cleaner, Topax 12, were each used in conjunction with a disinfectant (peroxide-peracetic-acid-based Oxomia Aktiv or potassium-persulphate-based Virkon). Results indicated that conventional cultivation methods combined with impedance measurements and image analysis of surfaces stained with AO or CTC-DAPI gave optimal readings which enabled the total evaluation of both biofilm removal and the destruction of bacterial cells. Use of the low-pressure cleaning system did not remove all bacterial cells from surfaces; bacteria remained even after use of the strong alkaline foam cleaner. The test rig protocol could also be used to evaluate sensitivity of microbial methods used in industry. [From En summ.]