Abstract

Wheat starch carbamates of different degrees of substitution were produced in laboratory experiments and for the first time their film forming performance were investigated. The carbamation reaction between urea and starch was investigated using a factorial design. Long reaction time, 2 h, and high urea content, 10 and 25%, resulted in a high degree of substitution, 0.07 and 0.15, respectively. These starch carbamates were assumed to be cross-linked and showed best film forming properties resulting in continuous and firm films. Furthermore, a high degree of carbamate substitution favored a decrease in glass transition temperature (T-g) in cast films. The addition of acid as a catalyst for carbamation of starch produced inconsistent results and mainly lead to degradation of starch molecules that caused brittle films. FTIR and C-13 NMR analyses confirmed the covalent bonding between urea and starch in starch carbamates. In a final step, production of starch carbamates was successfully scaled up. A potential industrial use of these starches is as oxygen barrier in multilayer food packaging. (C) 2017 Elsevier Ltd. All rights reserved.

Keywords

Wheat starch; Film formation; Molecular structure; Urea; Microscopy; Carbamate

Published in

Carbohydrate Polymers
2017, volume: 172, pages: 365-373
Publisher: ELSEVIER SCI LTD

Authors' information