CHEMICAL COMPOSITION, FUNCTIONAL AND PASTING PROPERTIES OF NATIVE AND ACETYLATED POTATO STARCH

ABSTRACT This study investigates the impact of acetylation on the proximate composition, functional, and pasting properties of Irish potato starch. Native and acetylated starches were analyzed to determine how chemical modification influences their physicochemical behavior and potential industrial applications. The proximate composition results revealed that acetylation caused a slight reduction in fat content (0.93% to 0.63%), ash content (0.67% to 0.45%), protein content (1.82% to 0.83%), and crude fiber (0.54% to 0.48%), indicating partial removal of non-starch components. Conversely, carbohydrate content increased from 85.84% in NTPS to 87.5 1% in acetylated potato starch, suggesting enhanced starch purity. Acetylation also introduced 1.204% acetyl groups with a degree of substitution (DS) of 0.046, confirming successful modification. Functional properties showed notable differences between native and acetylated potato starch. Water absorption capacity increased from 140% to 145%, indicating improved hydration ability. However, oil absorption capacity slightly decreased from 105% to 100%, suggesting reduced lipid-binding capacity. A Significant reduction in least gelation concentration (from 8.0% to 4.0%) was observed, highlighting improved gel-forming ability. Paste clarity remained similar, suggesting that acetylation did not significantly impact transparency. Pasting properties indicated that acetylation influenced viscosity behavior. Peak viscosity decreased from 1001 RVU to 945 RVU, suggesting lower swelling power. Trough viscosity also reduced from 521 RVU to 417 RVU, indicating weaker gel stability under shear. Breakdown viscosity increased from 480 RVU to 528 RVU, signifying lower paste stability under heat. Meanwhile, final viscosity dropped from 564 RVU to 493 RVU, demonstrating reduced gelling ability upon cooling. Pasting temperature slightly decreased from 76.0°C to 75.1°C, suggesting lower gelatinization energy requirements. Overall, acetylation improved hydration and gelation properties but reduced viscosity and paste stability. These modifications enhance the applicability of acetylated Irish potato starch in food processing pharmaceuticals, and industrial formulations requiring controlled thickening, moisture retention, and reduced retrogradation.