Characterization of functional polysaccharides extracted from pineapple stem and peel by-products

As the food industry embraces circular economy strategies, pineapple by-products such as stems and peels are increasingly recognized for their bioactive potential. These residues, often discarded as waste, contain valuable compounds such as polysaccharides, particularly galactomannans and arabinogalactans, which are known for their prebiotic effects, support of gut microbiota, and multifunctional roles in food and pharmaceutical formulations.

Pineapple stem and peel pomaces, derived from bromelain extraction, were subjected to green thermal extraction at 100 °C for 120 min and at a 0.01% solid-to-liquid ratio. Clarified pineapple juice, also obtained during bromelain recovery, was used as the extraction solvent to evaluate its effect on polysaccharide yield and extract properties. The extracts were analyzed for molecular weight and sugar profiling, thermal and colloidal stability, and structural analysis.

Extraction with clarified juice led to yields of 28% for stems and 36% for peels, suggesting enhanced solubilization, possibly due to synergistic interactions with the juice components. FT-IR analysis confirmed the presence of typical polysaccharide structures, including β-glycosidic bonds and hemicellulose-associated groups. HPLC profiling revealed a heterogeneous molecular weight distribution, characteristic of complex polysaccharide mixtures. Thermal analysis via DSC showed glass transition temperatures of 159–162 °C and endothermic peaks between 180 and185 °C, indicating thermal stability suitable for industrial processing. Zeta potential values ranging from –10 to –15 mV pointed to moderate colloidal stability, which may be advantageous for certain functional applications.
These findings highlight the physicochemical integrity and complexity of the extracted polysaccharides, supporting their potential as multifunctional ingredients, as well as stress the importance of exploring and utilizing food waste as sustainable rich sources of valuable compounds.

Pineapple stem and peel by-products serve as promising, renewable sources of structurally diverse and thermally stable polysaccharides. Through a biorefinery-based thermal extraction process, this study contributes to the valorization of food waste while supporting the development of sustainable, health-oriented food innovations.