Learning ultrasound assisted extraction through the use of sugar-coated chocolates

Extraction of bioactive compounds from vegetal matrices is a dynamic field in pharmaceutical, cosmetic and food industry. Many of these compounds have high medicinal value. Ultrasonic assisted extraction (UAE) becomes an interesting alternative to reduce both the amount of chemical solvents and the processing time. The aim of the present paper is to introduce, intuitively, the physical mechanisms involved in ultrasonic extraction for non-specialists. Two different mechanisms, cavitation and acoustic streaming, can be easily experimentally shown. The proposed experiment is the extraction of the sugar cover in sugar-coated chocolates. Extraction is analyzed using video tools to obtain a quantitative evolution of the process. Graphical results and videos are a useful tool for showing the basis of ultrasonic extraction in several levels from primary school to university students. In the event that the necessary ultrasound equipment is not available, we hope that the videos available in the supplementary material will be useful for teaching the topic.