AN ASSESSMENT OF CHEMICAL SANITIZERS ON THE MICROBIOLOGICAL PROFILE OF AIR IN A MILK PROCESSING PLANT

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.