Qualitative Assessment of Sonicated Apple Juice during Storage

Apple juice was subjected to ultrasound treatment at 30, 60 and 90% amplitude levels using probe‐type sonicator (20 kHz, 20C for 3 min) keeping pulse durations of 5 s on/off, and the samples were stored at 4C for 30 days. Effects of sonication and storage on total soluble solids (TSS), pH, titratable acidity, instrumental color (L*, a*, b*), nonenzymatic browning (NEB), cloud value, ascorbic acid and antioxidant capacity were evaluated. Additionally, sensory characteristics were also investigated. As results, TSS, pH and acidity remained unchanged while significant increases in color values, NEB, cloud value, ascorbic acid and antioxidant capacity were observed in all sonicated samples. Moreover, the consumer panel rated sonicated apple juice samples as most acceptable. Storage study showed significant increase in acidity, color values, NEB and decrease in pH, cloud value, ascorbic acid and antioxidant capacity. The results were further verified by principal component analysis. PRACTICAL APPLICATIONS: The use of nonthermal technologies for the production of fruit juices is a novel trend in food processing. Quality has always been in the spotlight because of its importance in defining customer preferences in purchasing food products. Therefore, meeting customer demands for convenience, health and sensory enjoyment are important for a product's success in the present market. The results of the present study revealed that ultrasound processing could improve and preserve more ascorbic acid, antioxidant capacity, cloud value and sensory characteristics of apple juice during storage. The technique is useful for manufacturers to produce more nutritious product with better taste and flavor than conventional methods for the benefit of consumers as they are now more conscious about health and diet.