Long standing applications of ultrasound in the food industry can be divided into two categories; low power ultrasound (low energy, high frequency) in the MHz range for non-destructive testing and high power ultrasound (high intensity, low frequency) in the kHz range for cutting and processing. In these days, when minimal and green processing is a driver for food preparation, power ultrasound affords useful possibilities for the food technologist. It has several positive aspects which can provide a range of applications in processing but perhaps more significantly it can provide concurrent combinations that include emulsification, extraction, sterilization, pasteurisation. controlled crystallisation/improved heat transfer and many more.
Amongst the applications of ultrasound in food technology we can include:
- Brining, Pickling and Marination involving penetration of liquids into food material and can be applied to both vegetable and meat products
- Tenderising meat this is normally achieved by pounding and ultrasound provides a mechanical vibration that can achieve similar results with less drastic mechanical damage.
- Cooking and Frying improved heat transfer gives shorter cooking times and more even cooking
- Drying and filtration air drying benefits from improved heat transfer but ultrasound has applications in filtration because it improves water flow through the filter cake
- Defoaming and Degassing is an important process for beverages before they are canned or bottled.
- Extraction the break-down of cell walls in plants together with improved solvent penetration results in better and sometimes more targeted extract yields of flavourings and nutriceuticals from plants, herbs and seeds.
- Sterilization, Pasteurization Conventional pasteurization and sterilization involves heating but this can result in nutrient loss and the development of undesirable flavours. Sonication reduces these problems by using lower temperatures and accelerating the process.