Continuous Vacuum Drying of Whole Milk Foam. III. Optimization Operations

A process for vacuum foam drying whole milk has been investigated. Preliminary work was done on mechanical modifications, development of techniques and instrumentation, and identification of the most important control variables. This paper discusses the subsequent phase of experimentation, wherein a three-year study was made, utilizing experimental designs and mathematical model simulation. The objective of the study was to determine operating conditions which would permit year-round operation, in spite of seasonal variation in milk foaming characteristics, at an economically desirable rate, with good product attributes. Conditions were found and tested in the pilot plant. Although no test has been made on highly stable (slow-drying) milk, the mathematical predictions were largely borne out in operation. The process was scaled up by two-thirds, and 42 trials were made during 4.5 months. Moisture and 5-hydroxymethy]furfural contents were consistent and adequately low.