ULTRASONIC
Low-temperature Processing
Ultrasonication is a non-thermal processing alternative for many liquid food products and is used widely in the food processing market. However, it has only just begun to be used for honey in recent years. Its mechanical power is being used for a gentle yet effective microbial inactivation and particle size reduction. Ultrasonic processing is an effective means to destroy undesirable components, such as crystals and yeast cells in honey. Less yeast means less chance of spoilage during storage and fewer crystals mean less heat is required to melt and filter the honey for creaming at a later date.
Ultrasonic non-thermal processing technology reduces HMF increase (heat damage) and creates better retention of diastase (freshness), aroma and flavour. In essence, it provides a better honey than traditional commercial honey processing.
Low thermal processing temperatures
Honey contains starch-digesting enzymes. Enzymes are sensitive to heat and heat treatment and therefore serve as an indicator of honey quality and degree of thermal processing. Ultrasonic processing reduces the need for excessive heating and keeps the honey at around body temperature - the right temperature for living food! Note the image on the left showing very low sonification temperatures are possible, however the general rule of thumb is to process just below 40 degrees C.
Yeast & microorganisms
Extracted honey contains undesirable materials, such as yeast (a high yeast count leads to rapid fermentation of honey) and other heat-resistant microorganisms. These elements are responsible for the spoilage of the honey during storage, however, when honey is exposed to ultrasonication, most of the yeast and microorganisms cells are destroyed. Yeast cells that survive sonication generally lose their ability to grow. This reduces the rate of honey fermentation substantially. Traditionally heat-treatment processing after extraction and filtration is used to reduce the moisture level and to destroy yeast but falls short in the destruction of heat-resistant microorganisms.
Ultrasonic liquefaction results in a greater retention of aroma and flavor creating a raw smooth creamy honey
Crystallisation & granulation
Honey naturally crystallises as it is a supersaturated sugar solution, with more than 70% sugar content relative to a water content of about 18%-19%. In packed honey, this leads to the formation of a liquid phase on top and a more solid crystalline form below which is not particularly appetizing to look at or eat.
Ultrasonication eliminates existing crystals and inhibits further crystallisation in honey. In this aspect, it is comparable to heating the honey but without the associated damage that heat causes. Ultrasonically aided liquefaction can work at substantially lower process temperatures of approx. 35°C and can reduce liquefaction time to less than 30 seconds.
1. Pre-Sonification: Grains visible (Left) 2. Post -Sonification refined grain (Right)