Deposition of Milk Solids on Heated Surfaces

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Abstract
The purpose of this investigation was to study certain factors which influence the deposition of milk residues on heated pipe surfaces. The amount of accumulated soil was determined by weighing the test pipes with a high capacity analytical balance. At flow rates less than 4,000 kg At. the amount of soil greatly increased, the relationship being log g soil = 7.69-2.00 log kg/hr. Soil deposits increased linearly as the temperature differential between milk and heating water increased linearly, significant deposits beginning at a heating water temperature of 52[degree] C above the entering milk temperature of 3 C. Adjustment of pH downward to 6.1 with hydrochloric acid greatly increased soil deposits at 2,500 kg/hr., slightly increased deposits at 3,600 kg/hr., and had no noticeable effect at 7,300 kg/hr. Entrained air with milk during heating unexpectedly did not result in increased deposits. Greater deposits were noted on pickle finish pipes and progressively less on 120, 180, and 320 grit finishes. Teflon-coated pipe showed more soil, but the soil peeled away on drying and under most conditions would not contribute to a cleaning problem.