Pectinase-assisted extraction of red dragon fruit (Hylocereus polyrhizus) juice: Process optimization and quality assessment

Abstract

Red dragon fruit (Hylocereus polyrhizus) is a nutritionally rich fruit; however, its high mucilage and pectin content hinder efficient extraction of clear, and high-yield juice without further processing. Among various green extraction methods, enzyme-assisted extraction with pectinase is a known method to improve juice extraction and its clarity, yet its application to red dragon fruit juice (RDFJ) remains insufficiently optimized. This study aimed to evaluate this by optimizing process parameters for enzymatic extraction of RDFJ from red dragon fruit by using the pectinase enzyme. The effects of independent factors enzyme concentration (0.1 to 0.5 %), incubation temperature (35 to 55 °C) and incubation time (100 to 140 min.) on the dependent variables juice yield, total soluble solids (TSS) and viscosity, were studied by employing Box Behnken Design. Quadratic models were used to examine the interaction between process parameters and responses. The optimal suggested parameters for maximizing juice yield (72.25 %) and TSS (11.01^°brix) while minimizing viscosity (4.33 cP) were at 0.3 % enzyme concentration, 45 °C incubation temperature and 120 min incubation time. Physicochemical properties, bioactive potential, and color attributes of the optimized juice were comprehensively evaluated and compared with a control juice produced without enzymatic treatment. Pectinase enzyme assisted extracted juice exhibited significantly higher yield, TSS, total phenolic content (192.72 mg GAE/100 mL), antioxidant activity (73.87 % DPPH inhibition), betacyanin content (62.31 mg/100 mL), reducing sugar (6.69 %) and total sugar (10.26 %) with lower vitamin C (13.26 mg/100 mL), viscosity and improved color characteristics compared to the control. Overall, pectinase-assisted extraction proved highly effective in enhancing the quality, yield, and bioactive potential of RDFJ, offering a viable strategy for developing value-added functional beverages and for integrating enzymatic green extraction into fruit processing and by-product valorization frameworks.