Functional and hypoglycemic dietary fiber from Queen pineapple peel waste by ultrasound-assisted alkaline extraction

The sustainable utilization of agro-industrial residues for the development of value-added functional ingredients has gained increasing attention; however, limited studies have explored the ultrasound-assisted recovery of dietary fiber (DF) from Queen pineapple peel, particularly with respect to its structure-function relationships. In the present study, peel waste from Queen pineapple cultivated in Tripura was investigated as a renewable source for DF extraction using an alkaline-assisted ultrasound-assisted extraction (UAE) technique. The extraction parameters were systematically optimized through response surface methodology (RSM), considering sonication time, ultrasonic amplitude, and solid-liquid ratio. Under optimal conditions (23 min sonication time, 47% amplitude, and 28 g/L solid-liquid ratio), the maximum DF yield reached 88.12%, which was substantially higher than that obtained through conventional alkaline extraction (65.21%). Comparative evaluation revealed that UAE-derived DF exhibited superior functional properties, including water-holding capacity (13.05 g/g), swelling capacity (7.62 mL/g), and cation exchange capacity (6.58 meq/g). The enhanced functionality was attributed to cavitation-induced structural disruption, increased porosity, and improved surface accessibility generated during ultrasonic treatment. Structural characterization through FTIR, XRD, and SEM analyses confirmed the presence of characteristic polysaccharide functional groups, enhanced crystallinity, and a well-developed porous honeycomb-like morphology. Thermal analysis further demonstrated improved thermal stability of the UAE-extracted DF. Moreover, the extracted fiber exhibited promising hypoglycemic potential through enhanced glucose adsorption capacity and glucose dialysis retardation index. Overall, the study demonstrates that alkaline-assisted UAE is an efficient and sustainable strategy for enhancing both the recovery and functional performance of DF from pineapple peel waste. Nevertheless, further in vivo studies and food application trials are necessary to validate its long-term nutraceutical potential and industrial applicability.