65B-25

H. Yan and G. V. BARBOSA-CáNOVAS. Biological Systems Engineering Department, Washington State University, Pullman, WA 99164

JUSTIFICATION: Compression tests have been used widely in pharmaceutics, ceramics, metallurgy, and civil engineering, as well as in the food powder field as a simple and convenient technique to measure such physical properties as powder compressibility and flowability. Compression behaviors were studied for some agglomerated food powders when padding materials were used in compression cells.

OBJECTIVES: Use a newly proposed padding index to quantify the compression behavior of selected agglomerated food powders affected by different thickness and positions of padding material in compression cells with different cell diameters.

METHODS: Size classified agglomerated coffee and milk powders were compressed by a piston attached to the crosshead of a TA-XT2 Texture Analyzer with a crosshead speed of 1 mm/sec and maximum load force of 245N. The internal diameters of compression cells were 21 and 30 mm. Compression tests were carried out under these conditions: with no padding, padding at the cell bottom, top, and middle with padding materials of 7 and 13 mm thickness, respectively. Powder bulk bed height was kept constant as 40 mm in all tests.

RESULTS: It was found that the thickness and position of padding material have significant effects on the compression deformation for each powder. When the same compression cell was used, compression deformation was significantly different if padding material was put at different positions in the cell. The padding index were 0.23~0.35 for agglomerated milk and 0.36~0.60 for coffee.

SIGNIFICANCE: The compression behavior affected by using padding material might be very useful in dealing with agglomerated food powders in processing, handling, transportation, and storage when padding materials are used to prevent compaction, attrition, and segregation.