Process Analysis of Antioxidant Biomass Extraction from Circular Pineapple Leaves for Functional Material Applications Using Response Surface Methodology

This study investigated the phytochemical composition of pineapple leaves, with a particular focus on flavonoids and polyphenols known for their strong antioxidant properties. The presence of allantoin, a compound recognized for its skin-repairing activity, was also examined. The primary objective was to optimize extraction conditions in order to maximize flavonoid content, total polyphenol content, and antioxidant capacity, thereby identifying the most effective parameters for antioxidant extraction. Powdered pineapple leaves were extracted using ethanol as the solvent. Initially, a one-factor-at-a-time approach was conducted to determine appropriate ranges for each extraction variable. Subsequently, Response Surface Methodology (RSM) was employed to optimize the extraction process, using extraction temperature (45°C, 50°C, and 55°C), extraction time (2, 3, and 4 h), and ethanol concentration (75%, 85%, and 95%) as independent variables. Under the optimized conditions, the maximum flavonoid content reached 5.20 mg rutin equivalents per gram, total polyphenol content was 63.53 mg gallic acid equivalents per gram, and DPPH radical scavenging activity achieved 92.72%. The ethanol extract exhibited a protein concentration of 9.21 μg/μL and a pH value of 5.96. Based on these results, the optimal extraction conditions were determined to be an extraction temperature of 55°C, an extraction time of 4 h, and an ethanol concentration of 85%.