SANITATION OF STAINLESS STEEL SURFACES CONTAMINATED BY STAPHYLOCOCCUS AUREUS
Microbial adhesion and control of biofilm formation challenge the food industries, as sessile microorganisms are more resistant to commonly used sanitizers. The objective of this study was to evaluate the efficiency of conventional and alternative sanitizers in the removal of biofilms, artificially formed with Staphylococcus aureus ATCC 6538 on small stainless steel blades (AISI 304 coupons), smooth and rough. The following sanitizers were tested: sodium hypochlorite (HNa 100mg/L), ozone (5mg/L), sodium dichloroisocyanurate (DCIS 100mg/L), alcohol 70%, water at 80ºC, ultraviolet (253.7 nm UV-C) and ultrasound (38KHz). 48 stainless steel coupons were used, 24 smooth and 24 rough, packed in separate vats containing 1000 mL of TSB broth and 1000μL of S. aureus suspension (1.5 x 108 CFU/mL). These were incubated in BOD at 20°C for 96 hours to promote microbial adhesion. Then, the sanitizing methods were employed and the microbiological assays were performed to verify the microbial reduction in the coupons. For smooth control coupons, the adhesion was 4.1x106CFU of S. aureus, and treatments with HNa, alcohol and DCIS had a 100% efficacy (reduction of 5 log cycles); Water at 80°C of 99.998% (reduction of 4 log cycles); Ozone of 99.83%, ultrasound of 99.78% and ultraviolet of 99.85% (reduction of two log cycle). For rugged control coupons, adhesion was 7.7x106CFU of S. aureus; treatments with HNa, alcohol and DCIS had an efficacy of 100% (reduction of 5 log cycles); Water at 80 ° C of 99.995% (reduction of 4 log cycles); Ozone of 99.59% and ultra violet of 99.22% (both presented reduction of two log cycles); and ultrasound 97.93% (reduction of 1 log cycle). It was concluded that DCIS, alcohol, HNa and water 80°C were the best sanitizers, presenting high applicability potential in the food industry.