Food Microbiology 83 (2019) 150–158
Resistance of thermophilic spore formers isolated from milk and whey products towards cleaning-in-place conditions: Influence of pH, temperature and milk residues
Carolin Wedel, Mareike Wenning, Anna Dettling, Siegfried Scherer, Jörg Hinrichs
University of Hohenheim, Institute of Food Science and Biotechnology, Soft Matter Science and Dairy Technology, Stuttgart, Germany
Technical University Munich, ZIEL-Institute for Food & Health, Chair of Microbial Ecology, Freising, Germany
The occurrence of thermophilic spore formers in dairy powders is a major concern for producers worldwide. This study aims to investigate the resistance of thermophilic endospores towards cleaning solutions typically used for cleaning-in-place in dairy manufacturing plants. From eleven tested strains, all were able to survive an alkaline treatment (NaOH) at 65 °C for 10 min (0.5%), whereas at concentrations of 2% eight strains withstood the treatment. Acid solutions were more sporicidal. At 0.5% of HNO3, only three strains survived the treatment. Milk impurities reduced the inactivation effect of the NaOH solutions towards thermophilic spore formers. For two selected strains, a detailed kinetic inactivation in NaOH and HNO3 solutions at different temperatures was performed and non-log-linear.
Cleaning-in-place, Thermophilic spore formers, Milk powder processing, Anoxybacillus flavithermus