Ultrasonics in Food Processing
- INTRODUCTION
Ideally, a food manufacturer would like to take a combination of raw materials and convert them into a high quality product at the lowest possible cost. This conversion is achieved by subjecting the raw materials to a number of processing conditions, e.g., heating, cooling, pressure, shearing or mixing.
Inherent variations in the raw materials and of the processing conditions mean that the properties of the final product vary in an unpredictable manner.
To control and minimize these variations food manufacturers need to characterize the properties of the raw materials, and to monitor the food at each stage of processing.
Food processing operations are becoming increasingly sophisticated and are often computer controlled.
Traditional chemical and gravimetric techniques are time consuming and laborious to carry out, and so there has been considerable motivation for the development of rapid analytical sensors for monitoring the properties of foods.
finding increasing use in the food industry for both the analysis and modification of food products.
The sound ranges employed can be divided into high frequency, low energy diagnostic ultrasound and low frequency, high energy power ultrasound.
The former is usually used as a non-destructive analytical technique for quality assurance and process control with particular reference to physicochemical properties such as composition, structure and physical state of foods.
Definition, Description and Applications
The definition of ultrasound is energy generated by sound waves of 20,000 or more vibrations per second. Presently, most developments of ultrasonics (sonication) for food applications are nonmicrobial in nature (Hoover 1997).
High frequencies in the range of 0.1 to 20 MHz, pulsed operation and low power levels (100 mW) are used for nondestructive testing (Gunasekaran and Chiyung1994).
Ultrasonic excitation is being examined for nondestructive evaluation of the internal quality and latent defects of whole fruits and vegetables in a manner similar to the use of ultrasound for viewing the developing fetus in a mother's womb (Mizrach and others 1994).
Floros and Liang (1994) noted the use of low intensity high-frequency ultrasound for improvement of food product/process monitoring due to the acceleration of diffusion.
These industrial applications include texture, viscosity and concentration measurements of many solid or fluid foods;
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