Technical Note: Optimization of Butter Churning Process with a Minitype Stirling Cooler

Abstract. In this study, a minitype Stirling cooler at laboratory level was used to produce butter. The obtained butter quality was affected by several parameters, such as initial fat content of material cream, loading capacity of material cream, running frequency of Stirling cooler, initial churning temperature, etc. To obtain a better application of the Stirling cooler to the butter churning process, the operating parameters that affected the butter churning process were optimized by an orthogonal test. The optimal group of main parameters was obtained, which were fat content of 20%, running frequency of 25 Hz, initial temperature of 12°C, and load capacity of 20 g, resulting in a cream separation time of 2 min. The physical properties of obtained butter from the Stirling cooler, such as color parameter, melting point, and texture, were analyzed and discussed. No significant differences in color and melting point were determined, but results showed different moisture and fat content. Several meliorations in the obtained butter from the Stirling cooler were compared with the control. The results offered some theoretical references in the application of the Stirling cooler on butter processing.