Numbers of Microorganisms Falling from the Air in Dairy Plants

Abstract

The air has long been recognized as one of the sources of the microorganisms in dairy products. The data reported in the literature (e.g., 9) indicate that the numbers of organisms falling into milk from the air in stables are relatively small, especially when the air is reasonably free from dust, and it seems probable that in dairy plants comparatively few organisms fall into the various products from the air. However, under certain conditions, a small number of organisms may be of great importance. The organisms may fall into a product in which they can grow or they may fall on equipment where moisture and nutrients permit growth so that the con~amination from this equipment is relatively heavy. I t is sometimes assumed that the microorganisms in the air of a dairy plant originate largely in the plant itself and in some cases attempts are made to reduce the numbers of organisms in the air by the treatment of certain rooms in a plant. For example, some butter printing rooms are fumigated in order to reduce the danger of the butter developing mold growth. Commonly, such treated rooms are thrown open to the outside air so that the comparative numbers of microorganisms in the air inside and outside a plant become of importance.