Abstract #72

# 72
Development of a method for characterizing high-protein dairy powders with an ultrasonic flaw detector.
Mary Hauser*1, Jayendra Amamcharla1, 1Kansas State University, Manhattan, KS.

When choosing a high-protein dairy powder such as milk protein concentrate (MPC), dissolution behavior is an important property to consider. Current methods for testing powder dissolution are time consuming, difficult to reproduce, and subjective. Ultrasound spectroscopy is a rapid and precise method, but expensive equipment and skilled technicians are needed. An economical alternative is to use an ultrasonic flaw detector (UFD). The objective of study was to develop a method to characterize the dissolution behavior of MPC with an UFD. The experimental setup included an UFD (Epoch LTC) in pulse-echo mode and a 1MHz immersion transducer that was kept a constant distance from the reflector plate. Powder concentration, stirring speed, UFD settings, and path length were optimized. To validate the method, 2 batches of MPC80 from a commercial manufacturer were procured and stored at 25°C and 40°C for 4 weeks. MPC was slowly added to water at a 5% concentration. During the dissolution, A-Scan data from UFD was acquired to calculate velocity and attenuation. Focus beam reflectance measurement (FBRM) and solubility index were used as reference methods. Velocity had a trend of fluctuating and then stabilizing with fluctuation time increasing with storage time. Due to the variation in fluctuation, the standard deviation from 900 to 1800s was set as a parameter. Day 0s standard deviation was 0.01 m/s and increased to 0.1 m/s after 4 wk at 40°C. During dissolution, attenuation increased and then gradually decreased. From the attenuation, 3 parameters were extracted. The area under the curve from 0 to 1800s showed the most changes. From Day 0 to wk 4 at 40°C, the area decreased from 100 to 110 Np·s/m to below 30 Np·s/m. After comparing all the data, it was observed that fresh powders dispersed quickly, had a low standard deviation and a larger area. As the MPC aged at 40°C, the particle dispersion rate decreased and an increase in standard deviation and reduction in area were observed. Overall, the UFD can be a low cost method to characterize the dissolution behavior of dairy powders.

Key Words: ultrasonic flaw detector, milk protein concentrate, solubility