The effects of novel clarifying agents and ultrasound application on clarification conditions and quality in the production of quince juice

In this thesis study, the investigation aimed to assess the effects of novel and traditional clarification agents in combination with ultrasound on the clarification of quince juice. For this purpose, the optimal temperature, duration, ultrasound frequency, and clarification agent combination were determined for producing clear quince juice. While novel clarification agents such as casein, chitosan, and xanthan gum were used, traditional clarification agents including gelatin, silica sol, and bentonite were employed. The best clarity value for quince juice clarified with a combination of contemporary clarification agents was achieved at 40°C temperature, 210 minutes duration, and a combination of 0.5 g/L casein, 0.01 g/L xanthan gum, and 0.075 g/L chitosan (2.82±0.02 NTU). In the case of quince juice clarified with a combination of traditional clarification agents, the optimum clarity was obtained at 40°C temperature, 120 minutes duration, and a combination of 0.05 g/L gelatin, 0.75 g/L kieselsol, and 0.75 g/L g bentonite (3.30±0.06). In the sample treated with ultrasonic technology, the lowest turbidity value was achieved when applying a 45 kHz ultrasonic frequency for 5 minutes (2.55±0.32). Laboratory scale production was carried out using the determined combinations in order to determine the quality characteristics of the clarified quince juice samples and to monitor the changes that occurred during storage. Quality characteristics such as turbidity, color, total phenolic substance, antioxidant capacity (DPPH, ABTS+, FRAP), pH, titratable acidity, water-soluble dry matter, browning index of quince juices clarified by different methods during the 0th, 2nd, 4th and 6th months of storage were determined. In conclusion, this thesis study demonstrates that the combination of modern clarification agents and ultrasound can be an effective alternative in the clarification processes of quince juice. The obtained data provide valuable insights into the selection of clarification agents, product quality, and cost implications in the fruit juice industry.