A novel efficient wet process for preparing cross-linked starch: Impact of urea on cross-linking performance

Yan Min; Jie Yi; Rui Dai; Wentao Liu; Hui Chen

doi:10.1016/j.carbpol.2023.121247

A novel efficient wet process for preparing cross-linked starch: Impact of urea on cross-linking performance

Carbohydr Polym. 2023 Nov 15:320:121247. doi: 10.1016/j.carbpol.2023.121247. Epub 2023 Jul 31.

Authors

Yan Min¹, Jie Yi², Rui Dai¹, Wentao Liu³, Hui Chen⁴

Affiliations

¹ College of Biomass Science and Engineering, Sichuan University, Chengdu 610065, China; Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065, China.
² College of Material and Textile Engineering, Jiaxing University, Jiaxing 314001, China.
³ College of Biomass Science and Engineering, Sichuan University, Chengdu 610065, China; Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065, China. Electronic address: liuwt@scu.edu.cn.
⁴ College of Biomass Science and Engineering, Sichuan University, Chengdu 610065, China; Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065, China. Electronic address: chenh@scu.edu.cn.

PMID: 37659826
DOI: 10.1016/j.carbpol.2023.121247

Abstract

Although wet processes are promising for preparing cross-linked starch, they are currently challenged by lower cross-linking efficiency and the requirement of large amounts of salts. Herein, an efficient and greener wet process was proposed, in which the cross-linking performance between sodium hexametaphosphate (SHMP) and starch was enhanced with the aid of urea. The maximum degree of substitution (DS) of the urea-phosphorylated cross-linked starch (UPCS) was 0.040 at 35 °C, while that of the conventional phosphorylated cross-linked starch (CPCS) was 0.031 at 45 °C. Compared with CPCS, the maximum DS of UPCS was elevated by 29.03 %, but its optimum cross-linking temperature was reduced by 10 °C, indicating that the cross-linking efficiency of this novel wet process was greatly improved by urea. The structural difference between UPCS and CPCS was confirmed by using a series of techniques including ³¹P NMR and ¹³C NMR. Zeta potential results suggested that urea may promote starch cross-linking by preventing the closure of active sites through hydrophobic interactions. Due to the structural reinforcement of starch by urea, UPCS showed better thermal stability, water resistance, acid and alkali resistance, and steady shear tolerance properties. This study provides a facile wet process for the fabrication and application of cross-linked starch materials.

Keywords: Cross-linking; Hydrophobic interaction; Potato starch; Sodium hexametaphosphate; Urea.