Related Literature and Studies
Ultrasonic, according to (Rouse, 2005), is energy in the form of waves having a frequency above the human hearing range. The highest frequency that the human ear can detect is approximately twenty thousand cycles per second or 20,000 Hz. This is where the sonic range ends, and where the ultrasonic range begins.
The use of ultrasound is an active subject within the food industry for both of the research and development. When the ultrasound propagates through a material it induces compressions and decompressions (rarefactions) in the particles of the medium, due to which high amount of energy is produced. Sound is a mechanical wave that travels in a straight line and also it requires a medium through which it travels. Ultrasound is a wave with a frequently exceeding the upper limit of human hearing which is greater than 20,000 Hz (Hertz). In ultrasound, the sound ranges can be broadly divided into two different categories. The one is low energy, high frequency diagnostic ultrasound in the MHz range and another one is high energy, low frequency, power ultrasound in the kHz range. So it is possible that ultrasound can be used for processing (Rana, Meena, & Shweta, 2017).
According to (Ercan & Soysal, 2013) Ultrasound can be used as a promoter or alternative to food processing. There may be numerous advantages of using ultrasound for food processing such as effective mixing, increased mass transfer, reduced energy, reduced temperature and increased production rate. Due to the elimination of microorganisms and enzymes without destroying nutrients of foods, ultrasound can be used as an alternative method to thermal treatments in the food preservation. Additionally, low power ultrasound is thought to be an attractive nonthermal method due to overcome problems which occur during heat treatments such as physical and chemical changes, nutritional loss and change in organoleptic properties.
According to (Wrigley & Llorca, 1992), Ultrasonic waves induce cavitation which is lethal for many bacteria. When Salmonella typhimurium was suspended in skim milk or brain heart infusion broth placed in an ultrasonicating water bath, the number of bacteria decreased by 2 to 3 log CFU in a time dependent manner.
According to (Chandrapala, Oliver, Kentish, & Ashokkumar, 2012), Ultrasonication can pasteurize and preserve the foods by inactivating many enzymes and microorganisms at mild temperature conditions, which can improve food quality in addition to guaranteeing stability and safety of foods