71A-33

L. Meunier-Goddik, D. D. HUEBSCH, and M. Nonnemacher. Dept. of Food Science & Technology, Oregon State Univ., 100 Wiegand Hall, Corvallis, OR 97331

Two important quality parameters for whey powder are hygroscopicity and flowability. Testing of these parameters is time-consuming and cannot be utilized as routine quality control testing in the commercial plant environment. Our objective was to develop a simple test for whey powder manufacturers to test the quality and to predict performance of their product upon delivery under challenged conditions. Four commercial whey powder samples were obtained from different processors. Flowability was determined using the “Fixed funnel and free-standing cone” method of angle of repose measurement. Modifications were then made. Whey powder was exposed to 80% relative humidity conditions, controlled by ammonium chloride in desiccators, for 24 hours immediately prior to analysis. Whey powder was sifted through a mesh colander into a No. 30 (.589mm) screen. The powder was sifted through the screen into a collection bowl and finally sifted into the funnel, set at 2 cm above the lab bench, using a No. 40 (.425mm) screen. Hygroscopicity was measured by passing air with a flow rate of 500 to 600 milliliters per minute and a relative humidity of 80% through a powder sample. Once equilibrium was reached, the difference in absorbed moisture was measured and hygroscopicity was determined as percent moisture uptake. There was no clear correlation between flowability, as measured by the original fixed funnel method, and hygroscopicity; R² =.0827. However, flowability, as measured by the modified method, correlated with hygroscopicity; R²=.9156 (Figure 1).  This relationship leads us to believe that a simple angle-of-repose test, after exposure to challenged conditions, can predict the hygroscopicity of whey powder. We believe that manufacturers can use this test to predict the performance of whey powders that are stored and distributed under high humidity conditions.

Session 71A, Dairy Foods: General
8:30 AM - 12:00 PM, Tuesday AM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana