Power ultrasound - current and potential
applications for food processing

Understand and consider the benefits and pitfalls of power ultrasound in food processing, a new technology that offers a route to new processes and products.

Power ultrasound is being re-evaluated as a potential food processing tool. It can be used in combination with other treatments, such as heat, to kill target bacteria and inactivate enzymes whilst retaining quality attributes ­ such as flavour, appearance, texture and nutritional value. Over recent years, significant effort has been directed at understanding the mechanism by which power ultrasound works and exploring its use in food preservation.

This review catalogues and assesses these developments. It explains what ultrasound is and the way in which it can be applied and presented to food products. It lists the broad applications that ultrasound has found in food preservation ­ ranging from crystallisation of fats and sugars through degassing of liquids, foaming and extraction of solutes to mixing, drying and meat tenderisation - and explains why some of these are seemingly contradictory (e.g. dispersion and agglomeration). It also describes the range of factors that can be used with power ultrasound as the basis for combination processes ­ including heat, pH and chemical preservatives.

Contents include:

• Introduction
• Definition of power ultrasound
• Generation of power ultrasound
• Applications of power ultrasound in the food industry
  - Enhanced oxidation
  - Stimulation of living cells
  - Emulsification
  - Extraction
  - Meat processing
  - Crystallisation
  - Degassing
  - Filtration
  - Drying
  - Gelling
• Ultrasound and heat transfer
• Inactivation of micro-organisms
  - Mechanism
  - Cavitation
  - Effect of treatment medium
  - Combination treatments
• Enzyme inactivation
• Food quality
• Conclusions and references