Sugar palm starch (Arenga pinnata) modification using microwave and acetylation: effect of moisture content and microwave power on physicochemical characteristics

Sugar palm starch (Arenga pinnata) can be utilized for food and non-food products. The natural properties of native starch are high viscosity, fast retrogradation problems,
unstable to heat and acid, and low paste resistance. Therefore, modifying sugar palm starch is necessary to improve its physicochemical characteristics. Microwave and
acetylation are reported to be effective modification methods. In this research, modification using a microwave was carried out at 13%, 18%, 23%, and 28% moisture
content, with a power of 200 W, 300 W, and 399 W. In general, increasing moisture content and microwave power could decrease starch, amylose content, and swelling power
while solubility increases. The higher power applied reduced the starch granule size and changed the pasting properties. All the treatments in this research did not change the
functional groups of the starch. The results showed that the starch with a moisture content of 13% and a microwave power of 300 W could most effectively reduce the granule size
and swelling power. Subsequently, this condition opted for a combination modification method with acetylation. The combination of acetylation and microwave modification on
sugar palm starch significantly decreased the starch and amylose content, swelling power, solubility, and granule size and changed the pasting properties of the starch. However, the combination of acetylation and microwave treatment had different effects on starch content and solubility compared to the single acetylation modification in particular. Overall, this result has demonstrated that dual modification of sugar palm starch could improve the limitation of its native characteristics in terms of granule size, swelling ability, gelatinization temperature, and retrogradation stability, which might be advantageous for specific purposes of food processing.