HIGH POWER ULTRA SOUND EQUIPMENT DESIGN:

There are three main components in a typical ultrasonic processing system:

1. The electrical power generator

2. The transducer

3. The emitter(s)

• The electrical power generator provides the energy for the system, which in most cases is an electrical current. An exception is the “liquid whistle,” which uses purely mechanical energy to generate ultrasound.

• The second component, the transducer, is the central element in any ultrasonic system. The transducer converts electrical energy (or mechanical energy) into sound energy through mechanical vibrations at ultrasonic frequencies.

• The third component, the emitter, is used to radiate (and in some cases amplify) the ultrasonic waves from the transducer into the medium. Emitters can come in the form of baths, horns, or sonotrodes.

• Several companies manufacture and supply ultrasonic processing equipment for the food industry. A few of the leaders are Branson, Danbury, Conn.; Australia-based Cavitus; Dukane, St. Charles, Ill; Hielscher, Germany; Innovative Ultrasonics, Australia; Sonimat, France; and Telsonic, Switzerland.

APPLICATIONS OF HIGH POWER ULTRASOUNDS IN FOOD PROCESSING:

DRYING:

• Removal of moisture by drying is one of the oldest method of food preservation. The use of ultrasound in combination with or prior to hot air drying was shown to have potential in increasing the drying rate without significantly affected the quality of the product.

• Ultrasound enhanced the mass transfer during drying of carrot. The product was dehydrated at low temperature therefore, the product quality was found to improve.

OSMOTIC DEHYDRATION:

• Osmotic dehydration is widely used for partial removal of water from food materials by immersion in a hypertonic solution.

• One of the main problem encountered while applying this technique is the usually slow kinetics of the process.

• Osmotic dehydration combined with ultrasonic energy reduced total processing time and increased effective water diffusivity in strawberries compared to osmotic dehydration, which alone increased processing time.

• Combined effects of micro-channel formation by high power ultrasound treatment and osmotic pressure differential were largely responsible for reducing drying time.