INVESTIGATION OF THE INFLUENCE OF ULTRAVIOLET LIGHT AND ULTRASOUND ON THE ANTIOXIDANT POTENTIAL, PHENOLIC CONTENT, AND STRUCTURAL-MECHANICAL PROPERTIES OF PEAR JAM ENRICHED WITH FIBERS

This study aimed to investigate the effect of ultraviolet light and ultrasound on the antioxidant activity and rheological properties of pear fruit jam. The antioxidant potential of fruit jam was determined by three methods based on different mechanisms (DPPH ABTS and CUPRAC assays) in six samples treated with ultrasonic waves and ultraviolet light. The antioxidant activity and the content of total phenols were preserved to the greatest extent during the irradiation of the fruit jam with ultraviolet light at a wavelength of 254 nm for a certain time. Ultrasound irradiation reduces the antioxidant activity and lowers the content of total phenols to a greater extent than the ultraviolet light. In addition, seven types of rheological parameters were determined on the pear fruit jam by a texture analyzer and their changes during processing with ultraviolet light and ultrasound was studied. Ultraviolet light demonstrated a smaller reducing effect on the rheological parameters of the fruit jam compared to ultrasonic irradiation. From the obtained results, the irradiation with ultraviolet light should be considered as a better technique for treatment of pear jam with minor changes in the antioxidant potential, phenolic content, and structural mechanical properties of the final product.