The pH-dependent phase separation kinetics of type-A gelatin and dextran with different initial microstructures

• Published in: Food hydrocolloids Vol. 134; p. 108006
• Main Authors: Wang, Qi, Han, Zhongqiu, Cui, Bo, Yuan, Chao, Li, Jianpeng, Nishinari, Katsuyoshi, Zhao, Meng
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2023
• Subjects: Dextran (DE); Microstructure; pH-dependence; Phase separation kinetics; Type-A gelatin (GE); Dextran (DE); Type-A gelatin (GE); Microstructure; Phase separation kinetics; pH-dependence
• ISSN: 0268-005X; 1873-7137
• DOI: 10.1016/j.foodhyd.2022.108006

The phase separation kinetics of type A gelatin and dextran (GE/DE) with different microstructures were investigated to get information on the relation between technofunctional properties and structures using static multiple light scattering (S-MLS), fluorescence microscopy, and macroscopic observations. GE/DE mixtures of 5.0 wt%/2.0 wt% and 5.0 wt%/3.0 wt% at pH = 5.50–9.00 were selected as the typical samples with the DE-in-GE and bicontinuous microstructures, respectively. Macrophase separation was found to occur in both the two mixtures at pH = 5.50–9.00 with the upper phase rich in GE and the lower phase rich in DE. However, the effect of pH on the phase separation rates of the two mixtures was different: pH-independent in DE-in-GE mixtures, while pH-dependent in bicontinuous mixtures. Specifically, the order of phase separation rates for the bicontinuous mixtures at pH = 5.50–9.00 was pH5.50 > pH6.00 > pH9.00 > pH7.00 ≈ pH8.00. Changes in the electrostatic interaction or steric exclusion effect among GE (DE) droplets at pH = 5.50–9.00 were used to explain the different phase separation kinetics of GE/DE mixtures with GE-in-DE, DE-in-GE, and bicontinuous microstructures. This work characterized the phase separation processes of GE/DE mixtures with three kinds of microstructure and provided the parameters for the phase separation kinetics at the macro-level. [Display omitted] •Phase separation kinetics of three microstructured gelatin/dextran were studied.•The effect of pH on gelatin/dextran phase separation was microstructure-dependent.•The phase separation rate of the dextran-in-gelatin was pH-independent.•Phase separation rates of gelatin-in-dextran and bicontinuous were pH-dependent.•Droplet interactions explain the pH-dependence of gelatin/dextran.