At present, the extraction methods of natural plant products mainly include water extraction method, solvent extraction method, enzyme-assisted extraction method, and ultrasonic-assisted extraction method, etc.
The water extraction method is simple, safe and pollution-free, but it takes a long time and has a low extraction rate; the solvent extraction method is easy to operate, but it requires a large amount of reagents, causes environmental pollution and has a low recovery rate.
The enzyme-assisted extraction method is simple to operate, has mild conditions, is environmentally friendly and harmless, but the extraction time is long.
Ultrasound extraction, as a modern developed technology, possess the advantages of efficient cell disruption, accelerated extraction, short extraction time, and high extraction efficiency. Moreover, it does not require complex equipment and is suitable for large-scale production applications in enterprises.
The characteristics of ultrasonic extraction technology
High extraction efficiency
The study on the ultrasonic extraction process of black bean protein revealed that when the ultrasonic extraction lasted for 19 minutes, the extraction rate of black bean protein reached approximately 50%, which was 10% to 20% higher than that of the conventional alkaline liquid extraction method.
Extracting at a low temperature
Ultrasound extraction mainly utilizes the cavitation and mechanical effects of ultrasound to break down the cell walls. This not only accelerates the extraction of natural products, but also eliminates the need for heating during the extraction process. Two methods, namely ultrasonic extraction and conventional water bath heating, were used to extract pigments from black bean skins. It was found that the ultrasonic extraction method not only had a higher extraction rate than the conventional water bath heating method by 8.3%, but also the extraction temperature was reduced from 80℃ to 50℃.
Bactericidal function
The research has found that ultrasonic treatment can inactivate Listeria bacteria, reducing their numbers; ultrasonic treatment can damage the integrity of the cell membranes of Escherichia coli, increasing the permeability of the cell membranes; ultrasonic treatment can also cause the cell membranes of Staphylococcus aureus to expand and make their cell boundaries become blurred.
Other
Ultrasound extraction can retain a large amount of natural active ingredients to a considerable extent, thus having a wide range of applications. Moreover, ultrasound extraction also has the characteristics of simple equipment and low energy consumption.