Sources of Psychrophilic Bacteria in a Dairy Plant With an Emphasis on Air

[From the Introduction]

The dairy industry generally recognizes that the psychrophilic bacteria are those bacteria which can grow in milk and milk by-products at refrigerated temperatures. Although psychrophiles have been recognized since the latter part of the last century, they were of relatively little importance in the dairy industry, as long as the milk and milk products were consumed within a reasonably short period of time after production or processing.

The presence of psychrophilic bacteria in milk has been attracting increasingly more wide spread attention since the early 1950's because of the introduction of bulk tanks on the farm, the related every other day pick-up and delivery, and subsequent storage prior to use. Because of these and related changes the dairy industry requires high quality milk that will maintain this quality for an extended period at refrigeration temperatures. The presence of certain types of psychrophillc bacteria in milk causes various off flavors and odors; this lowers quality and value. The present study was made in order to determine the various sources of psychrophilic bacteria in a dairy plant with special reference to air as one of the possible contaminating sources. Research data of this type may be of value to processors and quality control personnel of the industry.

Major is listed as Dairy Manufacturing.