17G-21 |
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Z. Liu, Department of Food Science, University of Arkansas, 2650 N. Young Ave., Fayetteville, AR 72704 and W. W. YANG, Department of Food and Animal Sciences, Alabama A&M University, 4900 Meridian St. N., huntsville, AL 35762. Apart from its industrial values such as a source for producing dietary fiber and corn fiber oil, corn pericarp is critical to germplasm identification during the transgenic process. Botanically, the pericarp is the ovary wall and is defined as a maternal tissue. In order to become a sample for genetic analyses, the pericarp should be very clean and contains little other components like endosperm, tip cap or aleurone fragments. Power ultrasound has been found to effectively loosen corn pericarp and make it pliable for separation by frictional milling. SEM examination of separated pericarp can help evaluate the efficacy of power ultrasound on pericarp separation. The objective was to examine the microsctructures of corn pericarp loosened by power ultrasound. After corn kernels were sonicated under different conditions, the pericarp was hand peeled. For the control sample, the corn kernels were soaked in water for 40 h at room temperature and then hand peeled. The inner surface of the pericarp was examined using a Hitachi S-230 SEM to observe the effect of ultrasonic frequency, power intensity and sonication duration on the microstructures of pericarp. SEM examination indicated that ultrasonic frequencies affected the size of the aleurone fragments attached to the inner surface of the pericarp. The aleurone fragment size decreased as the ultrasonic frequency increased from 40 kHz to 80 kHz. The power density and sonication duration affected the density of the aleurone tissue on pericarp. The aleurone fragment size decreased with the increased power intensity or sonication duration. Compared to 80 kHz, 40 kHz had more violent but less frequent cavitation, which led to larger sized but less dense aleurone fragments. SEM examination provides an effective means to evaluate the efficacy of ultrasound assisted pericarp separation process.
Session 17G, Food Engineering: Physical, chemical and electrical properties
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