## 3 The Influence of Ultrasound on the Physical and Chemical Properties of Juices  
Consumption of fruit, vegetables or fruit and vegetable juices significantly increases ingestion of microelements, mineral salts and vitamins, as well as antioxidants and fibre, which are invaluable in the proper functioning of the body. Many studies have shown that the substances contained in juices are absorbed much more efficiently by the human body than those that are supplied through various types of preparations (dietary supplements). Therefore, consuming juices that have unique compositions is recommended [14; 15]. Experts recommend that you try to consume juices more often than vitamin-mineral tablets. Regular consumption of fruit and vegetable juices allows you to supplement deficiencies of vitamins and bioelements. All the substances contained in the juice are delivered in the easiest form for cells to absorb; additionally, they do not burden the liver or the digestive system and are distributed throughout the body in an extremely fast time [16; 17]. The quality and safety of juices are extremely important for the health of consumers. With the increase in public awareness of the importance of nutrition, more and more emphasis is being placed on producers, because they are responsible for providing the highest quality of products. At the same time, they cannot forget about meeting the highest food safety standards [18; 19]. Undoubtedly, the raw materials used for the production of juices must be of a high quality. The healthiest are drinks made from fresh fruit and vegetables from controlled crops or organic sources. It is important not to use synthetic substances (preservatives or dyes) that may affect the final quality of the products [20; 21]. Careful observance of production processes allows for the preservation of the richness of vitamins, minerals and other nutrients present in raw materials [22; 23; 24]. It is also very important to adhere to the highest standards of hygiene throughout the production process to avoid contamination and the growth of harmful microorganisms. The use of appropriate pasteurization technologies or other preservation methods is crucial to eliminate potential health risks [25; 26]. Certifications such as HAACP (Hazard Analysis and Critical Control Points) or ISO (the International Organization for Standardization) are proof that the manufacturer applies rigorous procedures and complies with food quality and safety requirements [27; 28]. Consumers should choose juices with appropriate certificates to be sure that the product meets high standards. In addition, information on the packaging, such as the expiration date, ingredients, nutritional values and storage recommendations, helps consumers make the right purchasing and best-before decisions. However, in order for the juices to be safe and fit for consumption for a longer period of time, they must be properly preserved. Heating treatment methods will, however, affect the physical and chemical properties of these types of products to some extent. Therefore, new ways of preserving beverages have recently been sought, including the use of high hydrostatic pressure (HPP), pulsed electric field (PEF) or the increasingly popular ultrasound (US) [29; 30]. There are many studies on the effect of the sonication process on the physical and chemical properties of juices. For example, Gupta et al. [31] carried out sonication of pomelo juice. The scientists examined the chemical composition of the obtained product. In addition, they verified flavour compounds, including octanal, linalool, citral and ethyl butyrate, and as the analyses show, these substances were significantly enhanced, i.e., the taste of the juice was intensified. The hydrolytic activity of rhamnose and glucosidase was increased by the use of sonication, which resulted in a lower level of bitterness in pomelo juice.