No abstract

Sub-atmospheric steam at ordinary scalding temperatures was shown in laboratory tests to readily loosen feathers on dry birds. The possibility that this type of pure steam treatment can be used to avoid the conventional scald tank was investigated in a broiler and a turkey processing plant using a batch scale vacuum tank. Steam scalded birds were interspersed with birds on the same picking line used for tank scalded birds. Pure steam at sub-atmospheric pressure readily provided a uniform scald of either dry or damp birds. A steam temperature of 124°F. (51°C.) for 2 min loosened the feathers sufficiently to give clean broilers comparable to birds tank scalded at 128°F. (53°C.) for 2 min. Little or no abrasion of the outside occurred. Under subscald conditions (134-138°F.) typical subscald broilers, fowl, and turkeys were obtained by a 1 min. treatment.As anticipated, the air sacs of steam scalded birds had very few bacteria compared with the air sacs of tank scalded birds (more than 1,000-fold difference). However, after passing through the evisceration line and chiller the total bacterial load on the birds scalded by the two methods was similar.Steam scalded and tank scalded broilers had about the same shelf life at 37°F. (3"C.) and about the same degree of tenderness.

Fluid flow theory, as related to the holding of egg products in continuous pasteurization operation, is discussed. The conditions for laminar, turbulent and transitional types of flow; the specific factors in holding tubes that may cause deviations from the anticipated type of flow; and the effects of the viscosities of egg products are outlined. Retention times for laminar flow and the effects on survival of microorganisms are evaluated. Determination of minimum holding times in 10 commercial holding tube arrangements with varying egg products were made. All minimum holding times were appreciably less than average holding times but more than would be predicted from simple laminar flow theory. Holding tube efficiencies varied roughly from 60 to 80%. They increased slightly with increased Reynolds numbers over the range of the latter that is found in commercial holding tubes.