Thermosonication technology and its application in food industry

Abstract

Nowadays, consumers prefer nutritious and safe food products having natural taste and freshness. It is known that traditional thermal techniques can extend the shelf life of food products and their safety, but they cause loss in nutritional parameters. Thermosonication (TS) is an emerging non thermal processing technique used for food. It is a combined method of thermosonication and heat. The product is subjected to ultra- sound and moderate heat simultaneously and they both together have some synergistic effect. Thermosonication is a form of energy generated by sound waves of frequencies that are greater than the upper limit of human hearing range, typically above 20 kHz. By coupling thermosonication with thermal treatment, increased levels of microbial kill can be achieved while minimizing changes to the organoleptic properties of foods. The advantages of sonoprocessing over thermal treatment are minimal flavour loss, significant energy saving and greater homogeneit. The process of thermosonication has been used for microbial and enzyme inactivation. This method produces a greater effect on inactivation of microorganisms than heat alone. When thermosonication is used for pasteurization or sterilization purpose, lower process temperatures and processing times are required to achieve the same lethality values as with conventional processes. It is also more efficient, safe and reliable than thermosonication application alone by itself to achieve the limit of food-borne pathogens destruction. Thermosonication is a valuable method to reduce the microbial load, saving cost and energy and being less aggressive against food properties than heat treatments alone. The enzymes and microbial inactivation by thermosonication treatment is attributed to heat and cavitation, which is the phenomenon of formation, growth and explosion of bubbles in a liquid. During implosion, very high temperatures (approximately 5000 K) and pressures (estimated at 50000 kPa) are reached inside these bubbles. The explosion leads disruption of cell wall of micro-organisms causing their death. The process of thermosonication is used for extending the shelf life of liquid food like fruit juices.