On farm cleaning-in-place (CIP) vs multi-species biofilm: Rethinking hygiene strategies in raw milk bulk tanks

Microorganisms from both the farm environment and cows, including potential pathogens and spoilage bacteria, can enter the milking system through raw milk. Once introduced, they may attach to equipment surfaces and form multi-species biofilms that persist in milking and storage systems, compromising milk quality. Although cleaning-in-place (CIP) procedures are introduced to control biofilms, most studies have focused on mono-species systems, despite the dominance of multi-species biofilms (MSBs) in dairy environments. MSBs often exhibit tolerance to cleaning stresses and express distinct enzymatic activities, raising concerns about the efficacy of current cleaning strategies. This review summarizes CIP systems used on dairy farms, their effectiveness against biofilms, and laboratory approaches for biofilm cultivation and strain selection. It further discusses potential interactions within MSBs that enhance cleaning tolerance, aiming to inform strategies for safer, more sustainable dairy production and to guide future research on effective biofilm control.