Treatment and mechanism for hot melting starch by reducing the molecular chain winding and crystallinity

Shen Wang; Yanhui Li; Jingxian Zhang; Jia Man; Yanyan Nie; Maocheng Ji; Heyu Chen; Fangyi Li; Chuanwei Zhang

doi:10.1016/j.carbpol.2023.121574

Treatment and mechanism for hot melting starch by reducing the molecular chain winding and crystallinity

Carbohydr Polym. 2024 Feb 1:325:121574. doi: 10.1016/j.carbpol.2023.121574. Epub 2023 Nov 11.

Authors

Shen Wang¹, Yanhui Li¹, Jingxian Zhang¹, Jia Man², Yanyan Nie², Maocheng Ji², Heyu Chen³, Fangyi Li², Chuanwei Zhang⁴

Affiliations

¹ College of Mechanical and Electrical Engineering, Qingdao University, Qingdao 266071, China.
² Key Laboratory of High Efficiency and Clean Mechanical Manufacture (M of E), School of Mechanical Engineering, Shandong University, Jinan 250061, China.
³ College of Mechanical and Electronic Engineering, Northwest A&F University, 22 Xinong Road, Yangling, Shanxi 712100, China.
⁴ College of Mechanical and Electrical Engineering, Qingdao University, Qingdao 266071, China. Electronic address: zcwei@qdu.edu.cn.

PMID: 38008485
DOI: 10.1016/j.carbpol.2023.121574

Abstract

Unlike thermoplastic petroleum-based materials, starch-based materials rely on aqueous systems but are incapable of hot melting, resulting in low processing efficiency and limited large-scale industrial applications. In this study, the combination of α-amylase liquefaction and urea plasticization was used for the first time to obtain enzymatic thermoplastic starch (ETPS) for hot melting by changing the molecular chain of starch. ETPS showed an apparent hot melting phenomenon when heated below 200 °C. Differential scanning calorimetry revealed that heat absorption peaks were obviously reduced, and the hot melting phenomenon occurred easily depending on the combination of enzymatic hydrolysis and plasticization. Dynamic mechanical analysis indicated that the combined modification effectively increased the number of freely movable chains. The red shift of -OH stretching vibration peaks indicated the formation of strengthened hydrogen bonds in ETPS. X-ray diffraction showed that the crystallinity of ETPS was reduced to 5.68 %, effectively reducing the regenerative phenomenon. Gel permeation chromatography revealed that the molecular weight of ETPS decreased, and the entanglements between molecular chains were reduced. A tensile test showed that the elongation at break of ETPS was as high as 235.29 %, which was much higher than those of enzymatic hydrolysis starch and thermoplastic starch.

Keywords: Crystalline; Enzymatic hydrolysis; Enzymatic thermoplastic starch; Hot melting starch; Molecular chain winding; Plasticization.