This ongoing project to find new end uses for rice turned to a new area of research in 2007 – development of quick-cooking brown rice with ultrasonic technology. Experiments examined optimum cooking time, water uptake, and changes in volume and kernel length.

Rough rice samples of medium grain M-202 were used in the study. They were dehusked and milled to obtain both brown rice and white rice. Brown rice samples were treated with an ultrasonic system at a frequency of 16 kHz at full power for four durations (15, 30, 45, and 60 minutes) under two different water temperatures (77 and 104 degrees Fahrenheit). Treated samples were then air dried before being used in cooking tests.

Cooking characteristics of treated and untreated brown rice and white rice were evaluated and compared. Rice samples were also subjected to electron microscopy to obtain a visual picture of how rice kernel surfaces changed during the experiments.

Results showed that optimum cooking time of brown rice significantly decreased with the ultrasonic treatment – from 48 minutes to 28, 26, 26 and 24 minutes for the respective treatment durations cited above.

Ultrasonic treatments improved water uptake and increased volume expansion of brown rice. The treatments improved the capacity of starch granules to absorb water and expand compared to untreated brown rice.

Electron microscopy showed that surface microstructure changed, resulting in high water uptake during cooking and reduced cooking time. This research shows that ultrasonic treatment of brown rice can successfully be used to accelerate cooking of brown rice.