Effects of Enzymatic Hydrolysis Combined with Ultrasonic Treatment on the Properties of an Apple Juice Enriched with Apple Bagasse

The incorporation of apple bagasse (AB), a by-product of juice extraction, into apple juice can enhance its nutritional value while reducing food waste. This study investigated the effects of enzymatic hydrolysis (EH) and ultrasonic pre-treatment (US) on AB-enriched apple juice, focusing on its physicochemical, functional, and health-promoting properties. Apple juice was fortified with AB (1.5%, 3%, 4.5%) and subjected to EH using a cellulase-pectinase mixture for different durations (2, 6, 24 h). Optimal EH conditions (2 h, 3% AB) were combined with US (400 W, 8 min). Key parameters were analyzed, including total phenolic content, antioxidant activity, and glycemic response, alongside sensory evaluation. EH reduced particle size (D50), viscosity, and pH, while increasing GalA content, with effects intensifying over time. US further decreased D50 by 25.4% and viscosity by 39.7% but had no impact on other properties. Juices with 3% and 4.5% AB had over twice the phenolic content and 2.5–3× higher antioxidant activity. They also exhibited a potential hypoglycemic effect, with enhanced in vitro glucose retardationand lower blood glucose levels in 10 individuals. In conclusion, AB-enriched apple juice, treated with US and EH, showed higher nutritional value while maintaining acceptable sensory properties.