Improving properties of normal maize starch films using dual-modification: Combination treatment of debranching and hydroxypropylation

Structure and properties of films made from native, debranched, hydroxypropylated and debranched/hydroxypropylated normal maize starches were determined and compared. The modified starch films were much smoother and more integrated than native starch film. Especially, the particles were not observed in dual modified starch film but in debranched starch film, which might result from amylose recrystallization. Debranching substantially decreased elongation at break of starch films from 39.2% to 8.4% and hydroxypropylation decreased tensile strength from 4.82 to 2.92 MPa, indicating neither debranching nor hydroxypropylation could comprehensively improve the film properties. After dual-modification, elongation at break and tensile strength of the film were increased to 57.2% and 7.35 MPa, respectively. Moreover, the barrier performance of films was in the order of hydroxypropylated starch film < native starch film < dual-modified starch film < debranched starch film. It was suggested that dual-modification could be an effective approach to obtain starch films with tailor-made properties. (C) 2019 Elsevier B.V. All rights reserved.