Modification of Palmyra (Borassus flabellifer) Sprout Starch by Selected Chemical, Thermal, and Non-Thermal Methods: Effects on Physical, Functional, and Structural Properties

Native starches like palmyra sprout starch (NPSS) have limited industrial use due to restricted properties, and improving these properties is key for broader applications. This study examined NPSS modification through chemical (acid, alcohol, oxidation) and physical (cold plasma, microwave, autoclave, ultrasonication) methods to enhance the structural, thermal, and functional properties of palmyra sprout starch. NPSS showed a water absorption of 1.16 g/g, swelling power of 13.83 g/g at 75°C, solubility of 0.10% at 75°C, whiteness index of 80.23, peak viscosity of 4853 cP, and relative crystallinity of 66.73%. Significant (p < 0.05) changes in functional and structural properties were observed after modification. Microwave treatment yielded the highest peak viscosity (6507 cP), swelling power (17.80 g/g at 85°C), and setback viscosity (1509 cP). Ultrasonication increased peak viscosity (5868 cP), water retention (3.80 g/g at 70°C), and thermal stability (288.91°C). Oxidation resulted in starch with the highest water retention capacity (2.30 g/g at 90°C) and preserved crystallinity (79.10%). Acid-alcohol treatment achieved maximum solubility (4.13% at 95°C) but drastically lowered peak viscosity (13 cP). FTIR and XRD analyses showedthat ultrasonication and oxidation preserved glycosidic bonds and crystalline order, while autoclaving (peak viscosity 1904 cP) caused structural breakdown. These findings highlight the potential of tailored NPSS modification to enhance performance.