Isolation, characterization and evaluation of polysaccharides isolated from pineapple wastes as potential prebiotic / Siti Zulaiha Binti Zailani

Faculty of Industrial Sciences and Technology

Thesis (Master of Science) -- Universiti Malaysia Pahang - 2025

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The production and processing of Ananas comosus generate significant by-products such as leaves, peel, stem, and pomace, which often remain underutilized and contribute to environmental waste. These by-products have been reported to contain valuable compounds, including dietary fibers, sugars, proteins, minerals, and polysaccharides, which could serve as important sources of prebiotic growth factors for beneficial lactic acid bacteria (LAB). Given the increasing demand for natural and sustainable prebiotic materials, this study aims to extract and characterize polysaccharides from A. comosus wastes, evaluate their prebiotic properties, and assess their efficacy in enhancing the growth of Lactobacillus casei and Lactobacillus plantarum. Polysaccharides were extracted from various A. comosus wastes with yields of 13.9%, 18.3%, 9.46%, and 9.97% from leaves, peel, pomace, and stem, respectively, and characterized through measurements of neutral sugar and protein content, monosaccharide composition, thermal stability, FTIR, SEM, and 1H NMR analyses. HPLC revealed glucose as the primary monosaccharide. Thermal analysis indicated the polysaccharides exhibited stability up to 321 °C with weight loss profiles consistent with polysaccharide degradation. FTIR spectra confirmed the presence of hydroxyl, carbonyl groups, and glycosidic linkages, while SEM demonstrated a porous structure beneficial for water retention. 1H NMR confirmed predominantly β-D-glucose configurations, with minor α-D-glucose content in leaves and stem. The polysaccharides were resistant to simulated acidic and enzymatic digestion, indicating their potential to reach the colon intact. Supplementation of the polysaccharide extracts into modified MRS medium at concentrations ranging from 0.5% to 2.0% significantly supported the growth of L. casei and L. plantarum over 48 hours. Among the extracts, the peel extract demonstrated the most pronounced prebiotic effect, promoting the highest probiotic growth, followed by leaves extract, while pomace and stem showed lesser effects. Overall, the findings demonstrate that A. comosus waste polysaccharides are thermally stable, structurally suitable, and biologically active prebiotic substrates capable of effectively promoting probiotic growth. This study highlights the potential of utilizing pineapple processing by-products particularly peel as a sustainable and valuable source of prebiotics, offering promising avenues for reducing agricultural waste and developing functional foods.