STUDY THE INFLUENCE OF THERMAL PASTEURIZATION, ULTRAVIOLET AND ULTRASOUND IRRADIATION ON THE MECHANICAL PROPERTIES, ANTIOXIDANT ACTIVITY AND BIOACTIVE SUBSTANCES OF PEAR JELLY

The aim of this research was to investigate the impact of thermal pasteurization (TP), ultraviolet light (UV-C) and ultrasound irradiation (US) on the mechanical characteristics, antioxidant activity and bioactive content of fruit jelly. The preservation methods used were thermal pasteurization (TP), short-wave ultraviolet light (UV-C) and ultrasound (US) at 65°C/50 min for all methods. Nine types of mechanical properties of the jellies were determined by a penetration test using a texture analyzer. The influence of different low-temperature preservation methods on the antioxidant potential of the samples was investigated by three methods (DPPH, ABTS and FRAP) based on different mechanisms. The changes in bioactive components (total phenols, flavonoids, carotenoids and chlorophyll) during the technological treatment with different methods were determined. TP and UV-C did not significantly affect the mechanical properties of the samples, while US treatment made the gels firmer and more elastic. In TP, the antioxidant activity measured by FRAP assay was decreased by 50.64% and the total phenolic content was reduced by 46.66% compared to the control. Under UV-C irradiation, the antioxidant capacity according to the ABTS method reduced by 35.51%, while the content of total carotenoids was reduced 116 times compared to the control. US irradiation leads to a reduce in the radical scavenging ability of the jellies (DPPH method) by 35.15% and increases by 180.8% the content of total chlorophyll in the samples compared to the control sample.