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Abstract
Fouling in heat exchangers presents a significant challenge in the powdered infant formula industry, promoting microbial attachment and hindering heating efficiency. This study evaluated the attachment and thermal resistance of three Cronobacter sakazakii strains on stainless steel surfaces fouled with whey (WBF) and soy (SBF) based infant formulas. When bacterial attachment was assessed, attachment on medium foulant (5.63 log CFU/coupon) and high foulant (5.63 log CFU/coupon) was significantly higher than the clean coupon of 5.20 log CFU/coupon. Thermal resistance testing revealed that foulant layers could have impaired heat transfer, leading to greater bacterial survival. Clean coupons achieved a significantly greater reduction (p<0.001) in all isolates of C. sakazakii. D-value increased notably on fouled coupons averaging 4.70 min for WBF and 9.20 min for SBF, compared to 2.94 minutes on control coupons. Results indicate a need for stringent cleaning and sanitation protocols to prevent C. sakazakii harborage in processing environments.