AN ASSESSMENT OF CHEMICAL SANITIZERS ON THE MICROBIOLOGICAL PROFILE OF AIR IN A MILK PROCESSING PLANT
ABSTRACT The efficiency of chemical sanitizing agents to control the microbiota of milk processing areas at a dairy plant was evaluated. Diluted solutions of chlorhexidine digluconate at 1,000 and 2,000 mg.L−1, pH = 5.2 and 5.3, respectively; peracetic acid, at 45 and 75 mg.L−1, pH = 4.2 and 3.8; and a quaternary ammonium compound, pH = 9.2 and 9.3, respectively, were pulverized, at ambient temperature (20–25C) in the milk processing areas using spray equipment which produced a consistent fogging. For each 30 m2 of processing area, 0.5 L of sanitizer solutions were applied at 9 Kgf.cm−2 in 10 min. The sanitizer's efficiency was evaluated against mesophilic aerobic bacteria and yeast and molds. The microbial counts (APC) in the processing areas were detected by impaction technique, as proposed by APHA. Analysis were done before sanitizer application (T0) and after 0.5, 12 and 24 h (T1, T2 and T3), respectively. Activity of 2000 mg.L−1 of chlorhexidine and 700 mg.L−1 of quaternary ammonium against yeast and molds was observed. The T0 number of microorganisms (1.5 and 1.3 log cfu.m−3) decreased in 0.45 and 0.5 log cycle, respectively. Solutions containing 45 mg.L−1 of peracetic acid were effective to control mesophilic aerobic microorganisms. The T0 number of microorganisms (2.1 log cfu.m−3) decreased in 0.55 log cycle. Residual effects against yeasts and molds were observed for 1000 mg.L−1 of chlorhexidine digluconate and 75 mg.L−1 of peracetic acid. Chemical sanitizer applications to control the microbiological quality of the air in milk processing areas is a barrier technology that helps in the production of foods with good microbiological, sensory and organoleptic characteristics.
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ABSTRACT: The viable aerosol in dairy processing plant environments was characterized by using an Andersen six-stage sieve sampler and a Reuter centrifugal sampler. Artificially introduced Serratia marcescens were detected in the air during drain flooding and after rinsing the floor with a pressured water hose, thus illustrating the ability of a specific microorganism to be disseminated from drains and wet surfaces via physical disruption activities often observed in food plants. Once a high concentration of wet viable aerosol was generated, it took 40 or more min to return to the background level in the absence of forced ventilation or other activity. The greatest reduction in viable particles occurred during the first 10 min. Estimated mean aerosol particle sizes were decreased from approximately 4.6 to 3.2 mu with time lapse. The estimated mean aerosol particle sizes from actual dairy processing plant environments ranged from approximately 4.3 to 5.3 mu. In addition, a more heavily contaminated dairy processing environment contained larger aerosol particles. These results indicate that the RCS sampler will often overestimate the true aerosol concentration in highly contaminated air, because mean particle sizes are over 4 mu in diameter.Journal of Dairy Science 04/1990; 73(3):621-6. · 2.55 Impact Factor