Cross-linking Arenga pinnata starch and chitosan by citric acid: Structure and properties

In order to improve the processing and digestibility of the Arenga pinnata (Wurmb.) Merr. starch (APS), low concentration citric acid (CA) and chitosan (CS) were used for dual modification. The purpose of this study was to prepare APS and CS complexes with CA, the complexes (CA-CS-APS) physicochemical properties were investigated. The short-range ordered structure (DO), double helix structure (DO) and relative crystallinity (RC) were decreased; CA-CS resulted in the surface roughness of APS, but the particle integrity was preserved; the particle size of CA-CS-APS was increased. Compared with APS, the peak viscosity of CA-CS-APS was decreased from 2534 cP to 27 cP; CA-CS reduced the swelling power of APS, CA3%-CS-APS decreased from 19.00 g/g to 8.17 g/g. The gelatinization enthalpy was decreased after CA-CS modification from 3.25 J/g to 0.55 J/g. CA-CS-APS exhibits higher storage modulus and loss modulus (2067 Pa and 80 Pa). CA-CS significantly improved the anti-digestibility of APS, and the resistant starch (RS) content was increased from 32 % to 39 %. This study provided a simple and effective way to prepare modified starch, which had the potential as food additives or used as a base material for film preparation.