Evaluation of dairy powder products implicates thermophilic sporeformers as the primary organisms of interest.
Dairy powder products (e.g., sweet whey, nonfat dry milk, acid whey, and whey protein concentrate-80) are of economic interest to the dairy industry. According to the US 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 4 dairy powder processing facilities in the northeastern United States over a 1-yr period. Two separate spore treatments: (1) 80°C for 12min (to detect sporeformers) and (2) 100°C for 30min (to detect highly heat resistant sporeformers) were applied to samples before microbiological analyses. Raw material, work-in-process, and finished product samples were analyzed for thermophilic, mesophilic, and psychrotolerant sporeformers, with 77.5, 71.0, and 4.6% of samples being positive for those organisms, respectively. Work-in-process and finished product samples were also analyzed for highly heat resistant thermophilic and mesophilic sporeformers, with 63.7 and 42.6% of samples being positive, respectively. Sporeformer prevalence and counts varied considerably by product and plant; sweet whey and nonfat dry milk showed a higher prevalence of thermophilic and mesophilic sporeformers compared with acid whey and whey protein concentrate-80. Unlike previous reports, we found limited evidence for increased spore counts toward the end of processing runs. Our data provide important insight into spore contamination patterns associated with production of different types of dairy powders and support that thermophilic sporeformers are the primary organism of concern in dairy powders.
Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853.
M J
MJ
Watterson
Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853.
D J
DJ
Kent
Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853.
K J
KJ
Boor
Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853.
M
M
Wiedmann
Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853. Electronic address: nhw6@cornell.edu.
N H
NH
Martin
D000818:Animals; D003611:Dairy Products / Q000382:microbiology*; D003612:Dairying; D003625:Data Collection; D005511:Food Handling; D008892:Milk / Q000382:microbiology*; D008894:Milk Proteins; D009511:New England; D011208:Powders; D013171:Spores, Bacterial / Q000166:cytology*; D000067816:Whey Proteins
D008894:Milk Proteins; D011208:Powders; D000067816:Whey Proteins
mesophilic; milk powder; sporeformer; thermophilic