Understanding Transmission Of Sporeformers In Dairy Powder Products

Abstract

Dairy powder products (e.g., sweet whey, nonfat dry milk, acid whey, and whey protein concentrate-80) are of important economic interest to the dairy industry. According to the U.S. Dairy Export Council, customers have set strict tolerances (<500 to <1,000/g) for thermophilic and mesophilic spores in dairy powders; therefore, understanding proliferation and survival of sporeforming organisms within dairy powder processing plants is necessary to control and reduce sporeformer counts. Raw, work-in process, and finished product samples were collected from four dairy powder processing facilities in the northeast United States over a 1-year period. Two spore treatments were applied: i) 80°C/12 min for sporeformers and ii) 100°C/30 min for highly heat resistant sporeformers. Raw material, work-in-process and finished product samples were analyzed for thermophilic, mesophilic and psychrotolerant sporeformers resulting in 77.5%, 71.0% and 4.6% of samples positive for those organisms, respectively. Work-in-process and finished product samples were analyzed for highly heat resistant thermophilic and mesophilic sporeformers resulting in 63.7% and 42.6% of samples positive, respectively. Results varied considerably by product and plant; sweet whey and non-fat dry milk had the highest overall prevalence of thermophilic and mesophilic sporeformers, whereas acid whey and whey protein concentrate-80 had much lower levels. The results provide a preliminary evaluation of mesophilic and thermophilic sporeformers in various dairy powders. This study also revealed that thermophilic sporeformers are the primary organism of concern in dairy powders and that there must be further study of sporeformers, specifically, thermophilic Sporeformers, within the dairy powder processing continuum, to reduce overall spore counts in finished products. Key words: thermophilic, mesophilic, sporeformer, milk powder, whey