Presenting author: Luis Vargas

Co-author: Hao Feng

Department of Food Science and Human Nutrition

In an ultrasonication treatment, cavitation-induced activity may help increase transmembrane flux by changing plant cell membrane permeability and cell wall integrity. Moisture diffusivity is an important parameter in the design of drying processes. Changes in tissue structure caused by ultrasonication pretreatments might change the moisture diffusivity of plant tissues. Ultrasound-assisted blanching may improve moisture diffusivity during drying and inactivate enzymes. This study was undertaken to examine the moisture diffusivity of snap peas pretreated by ultrasonication. Fresh snap peas (0.50±0.1 cm diameter and 300±50 mg weight) were placed in distilled water at 80°C for 1 minute. The peas were then placed in a water tank and treated with ultrasound (20 kHz) for 3 minutes. Blanching only, ultrasonication only, and no treatment were used as controls. Treated samples were weighed and dried with hot air at 70°C for 400 minutes. The effective moisture diffusivities (Deff) of the snap peas were determined from the drying curves produced with a TA Instruments Q50 thermogravimetric analyzer, using the slope method. Two falling-rate periods were observed. The Deff for the ultrasonication pretreatment levels ranged from 1.4 x 10-8 to 1.9 x 10-8 m2/s for the first falling-rate period and 2.2 x 10-8 to 2.7 x 10-8 m2/s for the second. The ultrasonic-blanched samples dried faster than the samples with no treatment, blanching only and ultrasound only. Significantly different Deff values were observed between the treatments. A significantly higher Deff was achieved during the second falling rate in the ultrasound-blanched samples. Ultrasonic treatment can increase cell membrane permeability and cell wall damage, and may find use in drying enhancement for plant materials.